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Feeding and Aging Effects on Carcass Composition, Fatty Acid Profiles and Sensory Attributes of Muscles from Cull Cow Carcasses

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Title:
Feeding and Aging Effects on Carcass Composition, Fatty Acid Profiles and Sensory Attributes of Muscles from Cull Cow Carcasses
Creator:
STELZLENI, ALEXANDER MICHAEL
Copyright Date:
2008

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Subjects / Keywords:
Beef ( jstor )
Collagens ( jstor )
Fats ( jstor )
Fatty acids ( jstor )
Flavors ( jstor )
Least squares ( jstor )
Meats ( jstor )
Muscles ( jstor )
Slaughter ( jstor )
Steak ( jstor )
City of Gainesville ( local )

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University of Florida
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University of Florida
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Copyright Alexander Michael Stelzleni. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Embargo Date:
8/31/2007
Resource Identifier:
649814546 ( OCLC )

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FEEDING AND AGING EFFECTS ON CARC ASS COMPOSITION, FATTY ACID PROFILES AND SENSORY ATTRIBUTES OF MUSCLES FROM CULL COW CARCASSES By ALEXANDER MICHAEL STELZLENI A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2006

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Copyright 2006 by Alexander Michael Stelzleni

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iii This dissertation is dedicated to my wife , Elizabeth, my parents, Lynne and Michael Stelzleni and especially to my late Dedos (Grandfathers), Louis and William Lovacheff. Thank you for all of your help and encouragement.

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iv ACKNOWLEDGMENTS First, I would like to thank my wife, Elizabeth Stelzleni, for all of her sacrifices, patience and understanding with me while I was working th rough this degree program. Elizabeth not only helped me on numerous la te nights of studying and editing, but also managed to complete her bachelor’s degree in equine sciences, start her master’s degree in equine nutrition and is working on comple ting her master’s degree in the summer of 2006. I am very proud of Elizabeth and a ll of her accomplishments. I will never understand how a good woman keep s it all held together. I would also like to thank many faculty and staff members in the Department of Animal Sciences at the University of Flor ida for all of their support and aid during the past four years. After a year as Extension Programs Coordina tor I decided to re-enter the graduate program to complete my Doctor of Philosophy degree. During this transition period of my life, Dr. Joel Brendemuhl, Dr. Glenn Hembry, Dr. Tim Marshal, Dr. Robert Sand, Mr. Jerry Wasdin and the ranch crew at the University of Fl orida Beef Research Unit provided me with help in registering for graduate school, finding an advisor and providing me with a place to live. Their generosity will not be forgotten. A great deal of thanks is given to my major advisor, Dr. D. Dwain Johnson, for taking me as a graduate student and providing an assistantship so that I could complete my formal education in the field of meat science and beef production. Dr. Johnson’s patience, guidance and the freedom extended to me have helped me grow as a student and person. Appreciation is also given to the rest of my committee members, Drs. Sally

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v Williams, Todd Thrift and Ramon Littell, for th e aid in editing, research and statistics they provided. As well, a special thank you goes to Ms. Meghan Brennan of the IFAS Department of Statistics for all of her he lp and counseling. Her quick responses and willingness to meet were very much appreciated. There are many friends and coworkers that also deserve a word of thanks, namely Mr. Larry Eubanks, Mr. Byron Davis, Mr. To mmy Estevez and all the student employees of the University of Florida Meats Processi ng Center. As well, Ms. Doris Sartain and Mr. Frank Robbins deserve a nod of thanks. Without the help of these individuals, research and course work would have been nearly impossible. The friendships of Liz (Johnson) Greene, Nathan Krueger, Christy Br atcher and John Michael Gonzalez have also given a tremendous amount of support and relief throughout my research and graduate career at the University of Florid a. I would also like to thank the National Cattlemen’s Beef Association and the Florid a Beef Council for providing the funding, through Beef Check-off dollars, for the research that is contained within this document. Last but not least I would like to thank my family for their unwavering support for Elizabeth and me during the past four years of our lives. Working on graduate degrees and maintaining a healthy new marriage would have been much more difficult without the compassion of family members. Therefore, a great deal of gratitude is extended to my sister and brother-in-law , Jennifer and Todd Schwent, my in-laws, Melanie and James Eisenhour, my Baba (Grandmother), Dena Lovach eff, and especially my parents, Lynne and Michael Stelzleni. Without the he lp of these individuals my academic accomplishments would not have been possible.

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vi TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iv LIST OF TABLES...............................................................................................................x LIST OF FIGURES.........................................................................................................xiii ABSTRACT.....................................................................................................................xi v CHAPTER 1 INTRODUCTION........................................................................................................1 2 LITERATURE REVIEW.............................................................................................4 Effects of Grainor Forage-Feed ing on Beef Sensory Attributes................................4 Tenderness.............................................................................................................4 Juiciness...............................................................................................................11 Flavor...................................................................................................................13 Beef Flavor Intensity and Off-Flavor..................................................................16 Effect of Grainor Forage-Feeding on Beef (Off-) Flavor in Relation to Fatty Acid Profiles...........................................................................................................19 Effects of Postmortem Ag ing on Sensory Attributes.................................................24 Enzyme Systems Responsible for Tenderness During Aging.............................24 Effects of Aging on Sensory Attributes...............................................................27 Effects of Grainor ForageF eeding on Beef Collagen Content...............................29 Effects of Grainor ForageFeedi ng on Cook and Thaw Loss Characteristics.........32 Effects of Grainor ForageFeedi ng on Muscles and Lean, Fat and Bone Composition............................................................................................................36 Effects of Grainor ForageFeeding on Factors Affecting Quality and Yield Grade.......................................................................................................................41 Quality Grade Factors..........................................................................................41 Yield Grade Factors.............................................................................................43 Objective and Subjective Carcass Fat and Lean Color.......................................46 Carcass fat color...........................................................................................47 Carcass lean color.........................................................................................48

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vii 3 BENCHMARKING CARCASS CHARAC TERISTICS AND MUSCLES FOR WARNER-BRATZLER SHEAR FORCE AND SENSORY ATTRIBUTES FROM COMMERCIALLY AVAILABLE BEEF AND DAIRY CULL COW CARCASSES.............................................................................................................51 Introduction.................................................................................................................51 Materials and Methods...............................................................................................53 Carcass Selection.................................................................................................53 Warner-Bratzler Shear Force...............................................................................54 Sensory Attributes...............................................................................................55 Statistical Analysis..............................................................................................55 Results and Discussion...............................................................................................57 Carcass Characteristics........................................................................................57 Warner-Bratzler Shear Force...............................................................................61 Sensory Attributes...............................................................................................64 Implications................................................................................................................66 4 BENCHMARKING SENSORY OFFFLAVOR SCORE, OFF-FLAVOR DESCRIPTOR AND FATTY ACID PROFILES FOR MUSCLES FROM COMMERCIALLY AVAILABLE B EEF AND DAIRY CULL COW CARCASSES.............................................................................................................76 Introduction.................................................................................................................76 Materials and Methods...............................................................................................78 Carcass Selection.................................................................................................78 Sensory Off-flavor...............................................................................................79 Fatty Acid Extraction..........................................................................................79 Gas Chromatograph and Fatty Ac id Methyl Ester Analysis...............................81 Statistical Analysis..............................................................................................81 Results and Discussion...............................................................................................83 Sensory Off-flavor...............................................................................................83 Fatty Acid Composition......................................................................................87 Relationship of Fatty Acid s and Sensory Off-flavor...........................................89 Implications................................................................................................................92 5 EFFECTS OF REALIMENTATION ON CULL COW PERFORMANCEAND POSTMORTEM AGING ON CARC ASS AND PALATABILITY CHARACTERISTICS OF SELECTED MUSCLES...............................................105 Introduction...............................................................................................................105 Materials and Methods.............................................................................................107 Animal Selection and Treatment.......................................................................107 Carcass and Muscle Treatment..........................................................................108 Warner-Bratzler Shear Force.............................................................................110 Sensory Attributes.............................................................................................111 Collagen Analysis..............................................................................................111 Statistical Analysis............................................................................................112

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viii Results and Discussion.............................................................................................114 Live and Carcass Characteristics.......................................................................114 Collagen Content...............................................................................................119 Warner-Bratzler Shear Force.............................................................................120 Sensory Attributes.............................................................................................123 Implications..............................................................................................................125 6 EFFECT OF DAYS ON CONCENTRATE FEED ON SENSORY OFFFLAVOR SCORE, OFF-FLAVOR DE SCRIPTOR AND FATTY ACID PROFILES FOR SELECTED MUSC LES FROM CULL BEEF COWS................137 Introduction...............................................................................................................137 Materials and Methods.............................................................................................138 Animal Selection and Treatment.......................................................................138 Carcass and Muscle Treatment..........................................................................140 Sensory Off-flavor.............................................................................................142 Fatty Acid Extraction........................................................................................143 Fatty Acid Methyl Ester Analysis.....................................................................144 Statistical Analysis............................................................................................145 Results and Discussion.............................................................................................146 Sensory Off-flavor.............................................................................................146 Fatty Acid Composition....................................................................................149 Relationship of Fatty Acid s and Sensory Off-flavor.........................................151 Implications..............................................................................................................153 7 OVERALL CONCLUSIONS AND IMPLICATIONS............................................161 APPENDIX A BENCHMARKING THAW AND COOK LOSSES OF SELECTED MUSCLES FROM COMMERCIALLY IDENTIFIED FED AND NON-FED BEEF AND DAIRY CULL COWS AND USDA SELE CT A-MATURITY FED STEERS......165 B BENCHMARKING DEMENSIONS AND WEIGHTS OF SELECTED MUSCLES FROM COMMERCIALLY ID ENTIFIED FED AND NON-FED BEEF AND DAIRY CULL COWS AND USDA SELECT A-MATURITY FED STEERS....................................................................................................................170 C THAW AND COOK LOSSES OF SELEC TED MUSCLES FROM CULL BEEF COWS FED A CONCENTRATE DIET FOR 0, 42 AND 84 DAYS......................176 D DEMENSIONS AND WEIGHTS OF SELECTED MUSCLES FROM CULL COWS FED A CONCENTRATE DIET FOR 0, 42 AND 84 DAYS......................180 E COST AND PROFIT BREAKDOWN OF CONCENTRATE FEEDING OF CULL COWS FOR A SHORT DURA TION PRIOR TO SLAUGHTER...............186

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ix LIST OF REFERENCES.................................................................................................193 BIOGRAPHICAL SKETCH...........................................................................................207

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x LIST OF TABLES Table page 3-1. Least squares means for carcass characteristics1........................................................68 3-2. Least squares means for carcass composition1...........................................................69 3-3. Least squares means1 for Warner-Bratzler2shear force interaction of group by muscle.......................................................................................................................70 3-4. Warner-Bratzler shear fo rce and sensory attribute least squares means for the main effect of group.................................................................................................74 3-5. Warner-Bratzler shear fo rce and sensory attribute least squares means for the main effect of muscle...............................................................................................75 4-1. Least squares means for sensory off-flavor1 interaction of group x muscle..............94 4-2. Chi-square1 frequency2 distribution for off-fla vor descriptors by group..................98 4-3. Chi-square1 frequency2 distribution of off-fla vor descriptors by muscle.................100 4-5. Principal components analysis (PCA) for partitioning of fatty acid variance (percent of total lipid) for commercially identified fed and not-fed cull cows and Select A-maturity steers.........................................................................................103 5-1. Least squares means of live tra its prior to cull cow feeding....................................126 5-2. Least squares means for live performance and carcass characteristics.....................127 5-3. Least squares means for carcass composition1.........................................................128 5-4. Treatment main effect least sq uares means for collagen content.............................129 5-5. Least squares means for Warner-Bratzler2shear force interaction1 of treatment by muscle.....................................................................................................................130 5-6. Warner-Bratzler shear fo rce and sensory attribute least squares means for the main effects of treatment and days of aging..........................................................134 5-7. Warner-Bratzler shear fo rce and sensory attribute least squares means for the main effect of muscle.............................................................................................135

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xi 6-1. Main effect of days on concentrate f eed on least squares means for sensory offflavor score and Chi-square1 frequency2 distribution of off-fl avor descriptors for meat from cull cows...............................................................................................155 6-2. Main effect of muscle on least squares means for sensory off-flavor score and Chi-square1 frequency2 distribution of off-flavor descriptors for muscles from cull cows.................................................................................................................156 6-3. Least squares means for percent of to tal fatty acid (FA), concentration (mg/100g of meat), and ratios of saturate d (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids for the m. Gluteus medius (GLM), m. Longissimus dorsi (LOD), and m. Triceps brachiilong head (LON) for cull cows by days on concentrate feed..........................................................................157 6-4. Least squares means for concentrati on (mg/100g of meat) of saturated (SFA), monounsaturated (MUFA), and polyunsatur ated (PUFA) fatty acids for the m. Gluteus medius (GLM), m. Longissimus dorsi (LOD), and m. Triceps brachiilong head (LON) for cull cows by days on concentrate feed.................................158 6-5. Principal components analysis (PCA) for partitioning of fatty acid variance (mg/100g) for cull cows fed concentrat e diets for differing periods of time.........159 A-1. Least squares means for the main eff ect of group on percent thaw and cook loss..166 A-2. Least squares means for the main effect of muscle on percent thaw and cook loss167 A-3. Least squares means1 for percent thaw loss interaction of group by muscle...........168 A-4. Least squares means1 for percent cook loss interaction of group by muscle...........169 B-1. Main effect of group1 on least squares means for muscle2 dimensions3..................171 B-2. Main effect of group1 on least squares means for muscle2 weights3.......................173 B-3. Least squares means of pooled comme rcial and denuded muscle weights as a percent of hot carcass weight for main effect of group1.........................................175 C-1. Least squares means for the main eff ect of treatment on percent thaw and cook loss..........................................................................................................................1 77 C-2. Least squares means for the main effect of muscle on percent thaw and cook loss178 C-3. Least squares means1 for percent cook loss interac tion of treatment by muscle.....179 D-1. Main effect of treatment1 on least squares means for muscle2 dimensions3............181 D-2. Main effect of treatment1 on least squares means for muscle2 weights3.................183

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xii D-3. Least squares means of pooled comme rcial and denuded muscle weights as a percent of hot carcass weight for main effect of treatment1...................................184 E-1. Calculations of estimated percent lean for live cows...............................................188 E-2. Rough data for cow weights, percent lean and value...............................................189 E-3. Rough figures for calc ulating cost inputs.................................................................190 E-4. Final cost comparisons on a live weight basis for 8 head........................................191 E-5. Final cost comparisons on a hot carcass weight basis for 8 head............................192

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xiii LIST OF FIGURES Figure page 3-1.Warner-Bratzler shear force least square s means for the interaction of muscle by group for muscles of the chuck................................................................................71 3-2. Warner-Bratzler shear force least square s means for the interaction of muscle by group for muscles of the loin....................................................................................72 3-3. Warner-Bratzler shear force least square s means for the interaction of muscle by group for muscles of the sirloin and round..............................................................73 4-1. Sensory panel off-flavor1 least squares means for th e interaction of muscle by group for muscles of the chuck................................................................................95 4-2. Sensory panel off-flavor1 least squares means for th e interaction of muscle by group for muscles of the loin....................................................................................96 4-3. Sensory panel off-flavor1 least squares means for th e interaction of muscle by group for muscles of the sirloin and round..............................................................97 4-4. Chi-square1 frequency2 distribution for offflavor descriptors3 by group..................99 4-5. Chi-square1 frequency2 distribution for offflavor descriptors3 by muscle4.............101 4-6. Principal components plot for fatty acid analysis.....................................................104 5-1. Warner-Bratzler shear force least square s means for the interaction of treatment by muscle for muscles of the sirloin and round.....................................................131 5-2. Warner-Bratzler shear force least square s means for the interaction of treatment by muscle for muscles of the loin...........................................................................132 5-3. Warner-Bratzler shear force least square s means for the interaction of treatment by muscle for muscles of the chuck.......................................................................133 5-4. Overall sensory tenderness1 least squares means2 for the interaction of treatment by muscle................................................................................................................136 6-1. Principal components plot for fatty acid analysis.....................................................160

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xiv Abstract of Dissertation Pres ented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy FEEDING AND AGING EFFECTS ON CARC ASS COMPOSITION, FATTY ACID PROFILES AND SENSORY ATTRIBUTES OF MUSCLES FROM CULL COW CARCASSES By Alexander Michael Stelzleni August 2006 Chair: D. Dwain Johnson Major Department: Animal Sciences By feeding cull cows, it may be possible to increase the utilization and value of the carcass. Sensory data from the current study show ed that commercially identified beef non-fed (B-NF), beef fed (B-F), dairy non-fe d (D-NF), and dairy fed (D-F) cows were less tender (P < 0.05) than USDA Select grad e A-maturity beef carcasses (SEL), with BNF the least tender overall. Instrumental te nderness measurements revealed B-NF as the least tender (P < 0.05) and SEL as the most tender (P < 0.05). All cow groups exhibited increased (P < 0.05) beef flavor intensity rati ngs and increased (P < 0.05) off-flavor than SEL. Psoas major was the most tender muscle researched, with the Teres major and the Infraspinatus second and third. However, the Psoas major also had one of the highest levels of off-flavor de tection, along with the Gluteus medius and Triceps brachii -lateral head. Sensory off-flavor was not related (P > 0.05) to fatty acid prof iles in any group. When cull beef cows were fed a known concentrate diet for 84 days, live performance traits and carcass characteristics improved (P < 0.05) when compared to cull

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xv cows that were not fed prior to slaughter. In addition, lean color became a brighter more cherry red (P < 0.05) and fat color became wh iter (P < 0.05). Percent and total (mg/g) soluble collagen increased (P < 0.05) and four of the nine muscles examined had lower Warner-Bratzler shear force (WBS) scores af ter 84 days on feed. Sensory analysis showed that steaks from cows fed for 84 days were more tender (P < 0.05) and had less (P < 0.05) detectable off-flavor than steaks from cull cow car casses that were not fed. Postmortem aging 20 days increased sens ory tenderness and decreased WBS in cow steaks compared to steaks aged 10 days pos tmortem. Concentrate feeding of cows improved sensory off-flavor scores: however, the fatty acid profiles of steaks from these cows were not related (P > 0.05) to off-flavor score. Short-term feeding of cows for 84 days will substantially improve carcass characteristics and muscle quality, making them more acceptable for utilization in the beef industry.

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1 CHAPTER 1 INTRODUCTION Cull cows, which are cows removed from the production herd for various reasons, are an important part of the livestock and m eats industries. Cull cows may represent as much as 15 – 25% of total ranch revenues (Yager et al., 1980), making them a valuable asset to producers. The Na tional Cattleman’s Beef Asso ciation (NCBA) stated that producers could expect the most profit if cull cows were sold in proper condition. However, if producers did not sell their cull cows in decent condition they could lose as much as $22.35 of potential value per cow (NCBA, 1999). In 2004, cull cows represented approximately 15.8% of animal s slaughtered, equaling 5.1 million head and approximately 3.14 billion pounds of beef enteri ng the market. Of the 5.1 million head of cows that were slaughtered, 2.36 million were of dairy type and 2.7 million were of the beef type. Once processed in to edible beef, these animal s represented 12.96% of the domestic beef produced in 2004 (United Stat es Department of Agriculture [USDA], 2005). However, cull cows are separated at poi nt of slaughter into various groups based upon the perceived percent lean and quality of the carcass. In recent reports, a vast majority of cow carcasses were considered to have such inadequate muscling and such inferior quality (83.6% graded USDA Canner/Cu tter or below) that the carcasses were used only for lean trimmings and ground pr oducts (Cranwell et al., 1996b; NCBA, 1999; Roeber et al., 2001). If the condition a nd quality of cull cow carcasses could be improved, additional cuts could be obtained from the carcasses, therefore potentially increasing the overall salvag e value of the animal.

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2 Many researchers have examined the effect s of forageor concentrate-feeding on growth, carcass and quality characteristics of young cattle prior to slaughter (Bowling et al., 1978; Crouse et al., 1984; French et al., 2001). Finishing young cattle on concentrates rather than forages tends to increase quality, muscling, tenderness, heatliable collagen and overall palatability. As well, the effects of realimentation on cull cow gains, carcass characteristics a nd quality characteristics of the longissimus muscle have also been examined (Matulis et al., 1987; Bo leman et al., 1996; Cran well et al., 1996a,b). However, few studies were found in which th e effects of cull cow realimentation were examined on multiple muscles and only Warner-Bratzler shear force and sensory data were collected (Dryden et al., 1979). Along with light muscling and low quality, most cull cows are currently marketed at less than desirable body c ondition scores (NCBA, 1999; Roeber et al., 2001). It has been show n that if cull cows can be marketed at a moderate body condition score their carcasses and by-products may be more valuable and yield more useable product per carcass (Apple, 1999; Apple et al., 1999a,b). One way to increase cull cow body condition is to feed th em a concentrate diet prior to slaughter. Through realimentation cull co w carcass utilization may increase by making additional cuts from the carcass available for furthe r processing along with middle meats. Increasing beef demand and short supply ch ains have caused an increase in beef prices. In order to stay competitive with alternative protein sources, intermediately priced beef options need to be explored. Cu ll cow meat is a domestic option to fill beef supply gaps. Currently, cull cow condition, l eanness, light muscling and fat color are problems packers and processors must cont end with. Cull cow meat must also be acceptable in tenderness, quality and sensory ch aracteristics before it can be considered

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3 as a meat source to meet the demand for interm ediately priced beef options. Feeding cull cows is an option which needs to be expl ored thoroughly as a method for improving cull cow condition, carcass characteristics and qual ity. Feeding cull cows as a management practice could increase cow condition, carcass characteristics and quality, therefore making them a viable resource for manufactured beef products. The objectives of the current research were 1) benchmark the carcass characteristics and quality of cull cows curre ntly entering the supply chain when they are segregated at slaughter as either fed or non-fed beef a nd dairy types, 2) benchmark various muscles from fed and non-fed beef a nd dairy cull cow carcasses for size, cookery characteristics, tenderness, sensory and offflavor traits, 3) examine the effects of realimentation on cull cow performance, condi tion and carcasses charac teristics, and 4) examine the effects of realimentation a nd aging on muscle composition, cookery characteristics, collagen solubility, tendern ess, sensory traits, o ff-flavor production and fatty acid profiles of muscles other than the m. Longissimus dorsi . It is hypothesized that realimentation of cull cows may improve carcass condition, carcass characteristics and quality attributes of several muscles, th erefore making them available for further processing into intermediately priced beef cuts.

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4 CHAPTER 2 LITERATURE REVIEW Effects of Grainor Forage-Feed ing on Beef Sensory Attributes Tenderness Tenderness is arguably the most importan t sensory factor to consumers when deciding to purchase beef. Lawrie (1979) st ated that tenderness is the predominant quality determinant and the most important organoleptic characteristic of meat. However, the beef industry continues to st ruggle with producing a consistently tender beef product. The National Beef Tenderne ss Surveys revealed that variation in tenderness of steaks offered at retail was stil l an area of concern for the beef industry (Morgan et al., 1991; Brooks et al., 2000). There are many variables that constitute whether a piece of meat is tender or not. These include fragmentation, sarcomere length, moisture percentage and collagen content (Dav is et al., 1979). With this knowledge, it is imperative that the issue of tenderness be c onsidered when examining sensory attributes of beef muscles, especially when examin ing the effects of age and environmental conditions such as the diet an animal will receive prior to harvesting. Currently, there is conflicting research whether finishing beef on forage or on concentrates has an effect on meat tendern ess detected by Warner-Bratzler shear force (WBS). Schaake et al. (1993) fed A-matur ity steers between fescue-clover pasture (Group 1), fescue-clover followed by summe r pasture (Group 2) or fescue-clover followed by summer pasture and then drylot rations for 45, 75 or 170 days (Groups 3, 4 and 5, respectively). There was no differen ce in WBS values between Groups 2, 3 and 4

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5 for the longissimus muscle. Groups 1, 3 and 4 were also similar. However, Group 5 (the group fed grain the longest) was significan tly more tender than Groups 1, 3 and 4. Realini et al. (2004) researched the eating quality of Uruguayan beef fed a finishing diet of either concentrate or pasture. Concentrate and pastur e fed steers (age not given in the study) showed similar initial longissimus WBS values. However, pasture fed steers had lower WBS values at 7 and 14 days postm ortem when compared to concentrate fed steers. These results were not expected b ecause the pasture fed steers had less fat over the eye and the carcasses chilled quicker than did concentrate fed steers. Bowling et al. (1978) attributed tenderness diffe rences between pasture and gr ain fed beef to differences in muscle fiber contraction and sarcomere lengt h. It was concluded that forage fed beef was more likely to have cold shortening due to less fat cover. After 5 days of aging, major alterations in proteins become notic eable, including reduc tions in troponin-T and titin and the emergence of a new 30 kDa pol ypeptide that intensif ies by 10 days of postmortem aging (Xiong et al., 1996). Howeve r, in the study by R ealini et al. (2004), it was noted that more extensive aging was evid ent in the pasture fed steers than in the concentrate fed steers. Nuernberg et al. (2005) conc luded that feeding bulls to 620 kg live weight and allowing 12 days of conditioning tenderized the longissimus muscles from concentrate fed A-maturity bulls when compared to grass fed A-maturity bulls for either German Holstein or German Simmental breeds of cattle. It was stated that the grass fed bulls for both breeds were older than the concentrate fed bulls because it took them more time to reach the desired live weight. Purchas et al. (2002) reported a reduction in tenderness with increasing age from 8 to 10 months. It is well established that as age of cattle

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6 increases, so does collagen content. Nega tive correlations have been reported for WBS and growth rate (French et al ., 2001) and WBS and total collag en (Wheeler et al., 2002). Along with age, the pasture fi nished beef may have had co llagen that was more highly cross-linked due to the actions of locomotion re quired for browsing. Larick et al. (1987) reported that steers backgrounded on tall fescue, smooth bromegrass-red clover or orchard grass and then finished with 0, 56, 84 or 112 days on feed showed a significant increase in longissimus muscle tenderness from day 0 to day 84 with no change after 84 days on feed. Cranwell et al. (1996a), re searching the realimentati on of cull cows, reported longissimus muscle WBS values of 5.7, 4.9 and 4.9 kg for cull cows fed a high energy concentrate diet for either 0, 28 or 56 days , respectively. Cows receiving a concentrate diet for 28 or 56 days were significantly more tender than cows harvested off pasture. As well, Boleman et al. (1994) reported cull cows that were realimented for 56 days had lower WBS values than cows that did not receive concentrate feeding or were on a realimentation schedule of 28 or 84 days. In addition, Matulis et al. (1987) collected information on several muscles from non-fe d and realimented cull cows including the m. Semitendinosus , m. Biceps femoris and m. Longissimus dorsi . However, WBS data were only collected for the longissimus muscle. In this study, values increased slightly from 0 to 28 days on feed but decreased significantl y by 56 days on feed and remained similar to 56 day values at 84 days on feed. In 1996, Boleman et al. examined the e ffects of electrical stimulation and realimentation of mature cows for 0, 28, 56 and 84 days on longissimus muscle tenderness. Examining the time on feed and electrical stimulation interaction showed

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7 that non-stimulated cows had decreased WBS va lues as time on feed increased. Within the same feeding period, electrical stimula tion decreased WBS significantly. However, after cull cows were realimented for 84 days there was no difference in WBS values for steaks that came from stimulated or non-s timulated carcasses. Wh en time on feed data for 0, 28, 56 and 84 days was pooled, WBS values decreased significantly from 0 days on feed to 56 days on feed. Steaks from cull co ws that were on feed for 84 days had the lowest numerical WBS value; however, this wa s not significantly different from the cows fed for 56 days. This study also reported that 12th-rib fat thickness and WBS were significantly correlated, i ndicating that a partial reduction in WBS was due to an increase in fat thickness and therefor e a reduction in cold shorte ning and a possible increase in proteolysis. In the most inclusive cull cow realimenta tion project found to date, Dryden et al. (1979) examined the effects of age on realimentation and the effects of realimentation on 8 muscles from the chuck, loin and round. The 8 muscles examined included the m. Triceps brachii , m. Supraspinatus , m. Semimembranosus , m. Semitendinosus , m. Biceps femoris , m. Longissimus dorsi , m. Psoas major and m. Gluteus medius . Cull cows of ages 3, 6 and 10 were inve stigated in a first study . It was found that the m. Longissimus dorsi was the only muscle affected by age of th e cow, increasing in WBS value from 3 to 6 years of age and then decreasing by 10 years of age. However, this increase was not found to be significant. The reas on for decreased te nderness of the m. Longissimus dorsi in 6 year old cows was not readily known. Tuma et al. (1962) found that age of animal was much more relevant to tenderness between 18 and 42 mo nths than at 90 months of age. This could be attributed to the decrease in heat liable collagen and the increase of

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8 collagen crosslinking that occurs with in creasing age. Shimokomaki et al. (1972) concluded that the heat liable collagen linkage s decrease with age until almost absent at maturity. Hence, Marsh (1977b) concluded the quality of collagen (whether the tropocollagen molecule is cross-linked or not) may be a more important factor than the quantity of collagen present in meat. In a second study, Dryden et al. (1979) re ported that realimentation of cull cows varying in age from 7-10 years of age for 0, 38, 63 and 108 days had an effect on only 2 of the 8 muscles studied. The m. Semimembranosus decreased in WBS value for all feeding periods with a significant reduction occurring after 38 da ys on feed. Although there was a further reduction in WBS value at 108 days on feed, this was not different from the WBS values measured at 63 da ys on feed. Having the opposite effect, the m. Biceps femoris had similar WBS values for 0, 38 and 63 days on feed but then increased significantly by 108 days on feed. Overal l, Dryden et al. (1979) found that realimentation of cull cows for extended periods of time had little effect on increasing tenderness as measured by WBS in majo r muscles of the chuck, loin and round. Sensory panel tenderness is typically us ed in conjunction with WBS values to assess meat tenderness. Sensory overall tende rness is used to assign a value that will include myofibril tenderness and connective tissu e content of a particul ar piece of meat. Research conducted by Sapp et al. (1999) found that when steers were fed grass, grass followed by concentrate or concentrate only th at grass and concentrate fed steers were similar and more tender than steers fed grass fo llowed with concentrat e. Tenderness, in relation to sensory connective ti ssue content, followed the same trends as sensory overall tenderness. The differences in tenderness found in this study could be attributed to

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9 differences in connective tissue. Similarly, Schaake et al. (1993) reported no difference in sensory panel overall tenderness betw een forage and concentrate fed steer longissimus steaks when fed to a similar body weight. In this study, sensory pa nel tenderness ranking was different than the tenderness ranking that steaks received from their WBS values, where steaks from steers fed a concentrate di et for 170 days were more tender than steaks from steers fed a diet consisting of only fesc ue-clover grass. Bidne r et al. (1985) also reported that steers of similar age and fe d either common bermudagrass pasture or concentrates for similar times were not diffe rent in sensory overall tenderness for loin steaks. These findings are contradictory to wh at might be expected, considering all of the discussed studies show forage fed animals having less 12th-rib fat thickness than concentrate fed animals. Schaake et al. (1993) and Bidner et al . (1985) both reported 12th-rib fat thicknesses less than 6 mm for forage fed animals and 7 mm or greater for concentrate fed animals. Dikeman (1982) and Dolezal et al. (1982b) found that fat thickness less than 6.4 mm was conducive to cold shortening. Over the course of two years, Bidner et al. (1986) fed steers to a constant end point weight on either bermudagrass and ryegrass pastures or concen trates and found no signi ficant differences in sensory overall tenderness for stea ks from the rib, loin and top round. Conversely, Bennett et al. (1995) reported th at when steers were fed to a similar live weight on rhizoma perennial peanut gr ass or high energy grain, sensory overall tenderness scores rated grain finished steers as more tender. Ag ain, sensory panelists also detected more connective tissue in th e pasture finished steers. As would be expected, the grain finished steers had a fast er growth rate than the steers finished on forages (Bennett et al., 1995). Shackelford et al. (1994) suggeste d that there was a

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10 relationship between growth rate and pos tmortem tenderization, showing a negative correlation between growth rate and postmor tem calpastatin activit y. Hedrick et al. (1983) fed steers in four divergent manageme nt systems with a total of 13 different nutritional strategies consisting of feeding corn silage, drylot concen trate or pasture and variations of all three. Although there was variation within each management system, loin steaks from steers fed concentrate, corn silage followed by concentrate or pasture followed by concentrate were rated as more tender than steers fed only forages as a finishing diet. Sensory tende rness scores for samples take n from the top round tended to follow those of the loin, only to a lesser ma gnitude. Aberle et al. (1981) noted that growth rate of cattle prior to slaughter may be an important determinant of meat tenderness. In the study of Hedrick et al. (1983), steers finished on grass alone had the lowest rates of gain which could explain some of the differences in tenderness. Boleman et al. (1996) reported that feedi ng cull cows a concentrate diet for 0, 28, 56 or 84 days tended to increas e overall tenderness ratings for longissimus muscle steaks. Sensory panel ratings for ease of fragment ation also tended to increase. The study concluded that as time on a high-energy diet increased, m yofibrillar fragmentation became easier and detectable connective tissue decreased, contributing to the improvement in overall tenderness. Dryden et al. (1979) found that realimentation of cull cows that were between the ages of 7-10 y ears had no significant effect on the sensory overall tenderness of m. Semimembranosus or on m. Triceps brachii . However, realimentation did increase the overall te nderness of m. Gluteus medius and m. Biceps femoris when cull cows were fed a concentrate diet for an average of 63 days. Researching the sensory attributes of the longissimus muscle in realimented cull cows,

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11 Cranwell et al. (1996a) reporte d that sensory overall tendern ess increased from 0 to 28 days on feed, but showed no additional tender ness gained by feeding the cull cows for 56 days. Sensory panelists will often relate ov erall tenderness to other sensory attributes, such as myofibrillar fragmentation and dete ctable connective tissue. Along with overall tenderness, myofibrillar tenderness also increased from 0 to 28 days on feed and detectable connective tissue decreased with no additional ease in fragmentation or decrease in connective tissue by prolonged feedi ng. Heat liable collagen also increased with increased time on feed (Cranwell et al., 1996a). This could account for the difference in overall tenderness found by the sensory panel. Short-term realimentation appears to positively affect meat tenderness. However, this effect does not appear to be directly influenced by feeding but rather by an increase in external fat to prevent cold shortening or by increasing lean accretion which can affect collagen solu bility. Juiciness The sensory parameter “juiciness” has b een related to the amount of moisture released from the meat and the degree of sa livation induced during mastication (Lawrie, 1979; Muir et al., 1998a). This quality c ould have an important impact on overall palatability of steaks, even if the steaks are not thought be tender. Brown et al. (1979) found no differences in fat composition, moistu re composition or sensory panel juiciness when feeding steers diets c onsisting of low energy grass, low energy grass and limited grain or full grain. As fat composition levels increase, moisture composition levels will typically decrease (Van Koevering et al., 1995; Boleman et al., 1996) as a percent of muscle. However, with the loss of moisture, fat tends to protect the palatability (Smith and Carpenter, 1974) and perceived juicine ss of steaks by providing “insurance” against temperature abuse and drying out (Luchak et al., 1990; Parish et al., 1991 ). Gilpin et al.

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12 (1965) found that steaks with high marbling scor es were consistently ranked as having more juiciness than lower marbled steaks wh en evaluated by a trained sensory panel. Schroeder et al. (1980) reporte d that beef from foragea nd grain-fed animals showed no significant differences in relation to expressible moisture content of the longissimus muscle, but stated that the longissimus muscle from grain-fe d steers had increased marbling scores and ether extractable fat. The grain-fed steers from Schroeder et al. (1980) also scored higher for juic iness than the grass-fed steers. Dryden et al. (1979) reported no differen ce in sensory juicin ess between four muscles from cull cows, whether they were fed grass or concentrate prior to slaughter. However, panelists ranked the m. Gluteus medius as being the most palatable muscle studied, which numerically had the highest juiciness and tender ness ratings. The m. Biceps femoris was described as the second most acceptable muscle. Even though it was third in overall tenderness, it sc ored second in juiciness. Boleman et al. (1996) reported that when cull cows were realimented, juicine ss scores tended to increase. Steaks from cull cows fed a concentrate diet for 28 or 84 days had more detectable juice than steaks from cows that were not fed any concentrate. However, when cull cows were fed for 56 days, juiciness ratings were not different fr om cows not fed a concentrate diet. The reason for this discrepancy was not known sin ce cull cows decreased in moisture content and increased in ether extrac table fat and marbling linearly from 0 to 84 days on feed. There are many factors that contribute to juiciness of a steak when it is rated by a sensory panel. Moisture content, ether ex tractable fat or tota l lipid, cooking time, temperature and pH all play important roles. Additionally, Kim and Lee (2003) concluded that marbling appears to be an im portant factor in se nsory panel ranking of

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13 juiciness. However, in the current review of literature animals finished on grain tended to have increased marbling and ether extracta ble fat but exhibited little difference in juiciness. Beltran et al. (1997) found that st ressing cattle prior to slaughter increased pH values and water bi nding capacity of longissimus muscle. By action of increased pH, longissimus samples from animals in the high pH (> 6.3) groups were considered dark cutting and had an increased sensory juicine ss rating. Information relating ultimate pH to sensory juiciness for forage vs. concentrate fe d animals is scarce. However, Vestergaard et al. (2000a) reported that wh en young bulls were raised eith er extensively (pasture) or intensively (concentrate) that extensively ra ised bulls had carcasses with higher final pH values than intensively raised bulls. Vester gaard et al. (2000b) repor ted that even though pH values of the extensivel y raised bulls of Vestergaar d et al. (2000a) were not high enough to be classified as dark cutting, inte nsively raised bulls (w ith the lower pH) had juicier longissimus muscle steak s as determined by a trained sensory panel. Conversely, Bidner et al. (1986) reported no difference in pH values between grain or forage finished beef, but did show that the forage fed steers pr oduced beef that was juicier than the grain finished beef. However, both forage and grain fed beef were deemed to be only slightly juicy. To date, there is no conclusive ev idence that feeding forages or concentrates directly affects meat juiciness. Instead, ju iciness is influenced by indirect factors of feeding, such as intramuscular fat content and pH. Flavor Flavor is one of the most important quality attributes of meat. Meat flavor is a result of sensations arising from taste, aroma and pressureand heat-sensitive areas of the mouth (Moody. 1983). The flavor of meats have attracted much attention, but in spite of considerable research, a strong knowledge about the flavor co mpounds causing strong

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14 character impacts for meats of various species is limited (S hahidi, 1994). The flavor of beef has been investigated more extensively than any other m eat flavor. In its simplest format, it consists of tast e-active compounds, flavor enha ncers and aroma components (Macleod, 1998). Meat flavor and off-flavor are very complex issues with over 1000 volatile compounds contributing to species fl avor and off-flavors (Mottram, 1998) and 880 compounds have been identified in cooke d beef alone (Macleod, 1998). Species and off-flavor characteristics are commonly contained in fatty ti ssues and lipids, while lean tissues contain the precursors for meaty fla vors that are common in all cooked meats (Hornstein and Crowe, 1960; Wasserman a nd Gray, 1965; Mottram, 1998). Raw meat has very little aroma and only a blood-like ta ste, therefore meat flavor is thermally derived for the most part by the interacti on of various chemical compounds (Mottram, 1998). Taste-active compounds are factors that affect the senses of taste. Sweetness is primarily made up of sugars and L-amino aci ds. Sourness is made up of amino acids combined with succinic, lactic and carboxylic acids. The taste of saltiness is due largely to inorganic salts, while bitter ness is due to the presence of peptides, L-amino acids and hypoxanthine (Macleod, 1998). Hypoxanthine is a break down product of inosine phosphate (Foegeding et al., 1996 ). Flavor enhancers incr ease the savouriness or umami of meat products and mainly include L-am ino acids and 5’-nucleotides, primarily breakdown products of adenosine triphospha te including inosine monophosphate and guanosine monophosphate (Farmer, 1994; Macleod, 1998). Although taste-active and flavor enhancing compounds influence cooked meat flavor, it is the volatile compounds formed during cooking that determine the arom a attributes and contribute most to the

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15 characteristic flavor of meat (Mottram, 1998). Many aroma components are generated in beef from nonvolatile precursors on cooking. There are three primary reactions that occur in meat to release arom atics: 1) lipid oxidation and th ermal degradation, 2) thermal degradation of proteins, pep tides, amino acids, sugars and ribonucleotides (Maillard and Strecker reactions) and 3) thermal degrad ation of thiamine (Macleod, 1998). The Maillard reaction is classified as a non-en zymatic chemical reaction between an amino acid and a reducing sugar that is catalyzed by the addition of heat. During the reaction the carbonyl group of the suga r reacts with the nucleophi lic group of the amino acid producing a browning or carmelization e ffect and gives off oderous compounds (BeMiller and Whistler, 1996). The Maillard reaction may also occur through carbonylamine reactions where a protein or ami no acids provides the amino component and reducing sugars, ascorbic acid or carbonyl compounds generated from lipid oxidation provide the carbonyl component. When carbonyl derivatives fr om the Maillard reaction react with free amino acids they can degr ade the amino acids to form aldehydes, ammonia and carbon dioxide through a pr ocess known as Stecker degredation (Damodaran, 1996). Singularly, aroma compounds can represent many different sensations. However, many times aroma compounds work together to produce a desirable smell or olfactory response. For example, in the Maillard re action one amino acid and one sugar have the ability to yield hundreds of compounds, depe nding on the rate of reaction which is dependant upon the sugar involved (Farmer et al., 1989). Some of the more important volatiles in cooked beef include trans-2-nonenal, trans, trans-2, 4-decadienal and 1-octen3-one from thermal oxidation of long-chain fatty acids. From Maillard reactions of

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16 proline and cysteine-ribose, 2-acetyl-1-pyrroline and 2-met hyl-3-furanthiol are formed, respectively. Strecker degradation produces methional and phenylacetaldehyde from methionine and phenylalanine, respectivel y. Two of the most important aroma compounds are formed by the thermal degrada tion of thiamine to produce bis 2-methyl-3furyl disulphide and 2-me thyl-3-furanthiol, and -carotene undergoes oxidative degradation to form -ionone. Separately these com pounds form aromas ranging from fried potatoes to violet-like, but together they work synergistically to produce cooked beef flavor (Farmer, 1994). Aroma compounds can also be detrimental to desirable beef flavors. Lipids can break down via oxidati on of fatty acids and give volatile aroma compounds which contribute to undesirable flavors (Mottram, 1987). Lipid derived volatiles, usually in the form of intram uscular triglycerides and phospholipids, are quantitatively dominant. It is only in m eat grilled under severe c onditions that Millardderived volatiles are the ma jor components (Mottram, 1985). The effects of lipids and fatty acids on flavor production will be di scussed in a subsequent section. Beef Flavor Intensity and Off-Flavor Genetics and environment influence meat flavor, with species as the most important genetic factor and feed source as the most important environmental factor (Shahidi et al., 1986). High-en ergy grain diets tend to produce a more acceptable or more intense flavor in red meats than low-ener gy forage or grass di ets (Melton, 1990). Schaake et al. (1993) reported that longissimus steak beef intensity flavor was higher for steers fed a concentrate diet than steers fed grass only diets. However, flavor desirability, determined by first and second off-flavors, was not different betw een concentrateand grass-finished steers. It was noted though th at grass and warmed-over flavors decreased as steers were fed concentrates. Bennett et al. (1995) found that the incidence of off-

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17 flavor was greater for forage fi nished steers than for concentrate finished steers. Thirtysix percent of the forage finished steaks we re described as having off-flavors while only 14% of the steaks from concentrate fed steers had detectable off-fla vors. Contrary to Schaake et al. (1993), Hedrick et al. (1983) reported less flavor desirability for loin steaks and top round roasts from steers finished on forages when compared to steers finished on concentrate. The fla vor difference between the groups was attributed to the difference in volatiles from the fat report ed by Hedrick et al. (1980). Nuernberg et al. (2005) repor ted no differences for beef flavor or any off-flavors for steaks from grass or grain fi nished steers, except for an increase in fishy flavors that were noted for grass fed steers. The increase in fishy flavors was attri buted to an increase in long-chain n-3 fatty acids found in the meat samples from grass-fed steers. Likewise, Sapp et al. (1999) also reporte d no difference in beef flavor intensity between grass and grain fed steers. In addition, however, there was a significant increa se in incidence of off-flavor for the grass fed steers. Schroe der et al. (1980) found grain fed steers had increased flavor desirability and beef inte nsity flavor, while grass fed steers were reported to have increased aromatics. Larick et al. (1987) reported the sensory panel’s perception of grassy flavors decreased as tim e on feed increased. Loin steaks and ground beef of carcasses from steers slaughtered direc tly off pasture had the highest grassy flavor scores, followed by reductions in grassy fl avor from steers fed grain for 56, 84 and 112 days respectively. However, Bidner et al . (1985), Wu et al. ( 1981b) and Crouse et al. (1984) all reported no significant differences be tween grass and grain finished steers for beef flavor intensity or flavor desirability.

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18 Hilton et al. (1998) reported that am ong mature cow carcasses (C, D and E maturities), yellow-colored fat was associated with increased detection of grassy and fishy flavors. Yellow colored fat pigmentation (discussed in a later section) is associated with grass feeding and an increase in caroten e content being deposited in the fat. Dryden et al. (1979) found that there was no difference in flavor for four muscles from cull cows that were slaughtered directly off grass or fed concentrate for 38, 63 or 108 days. However, concentrate fed cows did have numer ically higher scores for increased flavor desirability. It was also reported that cooking temperatur e did impact flavor. When m. Semimembranosus steaks were cooked to an internal temperature of 135C, steaks from concentrate fed cows had a more desirable fla vor. This difference disappeared as internal temperature was increased to 163C. Cranwe ll et al. (1996a) found as cull cows were realimented, beef flavor intensity increased at 28 days on feed but no further increases were noticed. Boleman et al. (1996) also noticed an increase in beef intensity flavor for cull cows as they were realimented, but this increase in intensity did not occur until 56 days on feed. However, it was noted that a decrease in off-flavor was noticed after 28 days on feed. Faulkner et al. (1989) reporte d realimented cull cows had increased beef intensity flavor and flavor desirability af ter 42 days on feed but realimentation did not impact off-flavors detected by the sensory panel. Conversely, Miller et al. (1987) reported feeding cull cows a high energy diet decreased flavor intensity (although only by 0.1 on an 8 point hedonic scale) and increased the intensity of off-flavors when compared to cull cows on a low energy maintenance diet. There are a multitude of factors that can affect meat flavor, however, lipi ds via fatty acids or lipid de rived volatiles appear to have a large influence on flavors that are produced.

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19 Effect of Grainor Forage-Feeding on Beef (Off-) Flavor in Relation to Fatty Acid Profiles Many researchers have current interests in finishing cattle on forage based diets to examine if there are any health benefits via an increase in desirable fatty acids (French et al., 2003; Realini et al., 2004; Valsta et al., 2005 ). Interest in meat fatty acid composition stems mainly from the need to find ways to produce healthier meat, i.e. meat with a higher ratio of polyunsaturated (PUFA) to saturated (SFA ) fatty acids and a more favorable balance between n-6 and n-3 PUFA (Wood et al., 2003). The addition of a concentrate diet has been shown to produ ce more SFA and monounsaturated fatty acids (MUFA) in carcass tissue while forage feeding produces carcasses with an increase in n-3 PUFA content (Raes et al., 2003; Elmore et al., 2004). The largest difference in flavor precursors between grassand grain-fed beef o ccurs with alterations of these fatty acids (Melton, 1983). Because of the many types of forages used to finish cattle, it is impossible to make a simple conclusion concerning the effect of all forage diets on beef flavor (Melton, 1983). The impact of replacing concentrate with forage on off-flavor has been studied. Melton (1983) reviewed severa l works in which different lo wer quality grasses produced undesirable flavors. Among the grasses re ported were bromegrass and bluestem (Harrison et al., 1978); warmand cool-seas on grasses (Smith et al., 1977); fescue, orchardgrass and clover (Davis et al., 1981); oats, rye and ry egrass (Reagan et al., 1977); and costal bermuda grass (Bowling et al., 1978; Dolezal et al., 1982a) to name a few. However, Larick and Turner (1990a) reporte d no difference in offflavor notes between heifers fed millet, sorghum sudangrass or fesc ue-clover. As well, Larick et al. (1987) also reported no difference in off-flavors in st eaks or ground beef from cattle finished on

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20 tall fescue, smooth bromegrass-red clover or orchardgrass-red clover. Examining effects of finishing diet on beef flavor, Smith et al . (1977) and Harrison et al. (1978) reported no differences in off-flavor when co rn was replaced with corn silage. In general, part of the corn in a high concentrate diet can be repl aced with corn silage or alfalfa without detriment to flavor. However, if corn or co rn silage is replaced with something other than high quality hay, large flavor di fferences may occur (Melton, 1983). Grass diets also affect several fatty acid s such as branched-chain fatty acids, oddnumber carbon-chain-length fatty acids a nd long-chain polyunsaturated fatty acids (Melton, 1983). Cattle fed forage diets have been shown to have more C18:3, C20:3, C20:4 and C22:5 in lean tissue samples wh en intramuscular fat and phospholipids are examined, while grain fed cattle typically have increased n-6 fatty acids (Raes et al., 2003; Elmore et al., 2004). Hi gher C18:3 content in beef produced by grass is due to the high concentration of C18:3 (approximately 50 %) in grass lipids (M elton et al., 1982). Longer-chain fatty acids are also present in fo rages, explaining their presence in beef tissues when cattle are finished on forages (E lmore et al., 2004). These fatty acids are found in the phospholipids of beef tissue more so than in the intramuscular fat (Igene and Pearson, 1979). Mitchell et al. (1991b), however, did not report any significant differences in long-chain fatty acids (C18:3, C20:4, C20:5 and C20:6) in loin or rump steaks from cattle finished on grain or grass based diets. Brown et al. (1979) reported that grass fed beef had more off-flavors a nd higher concentrations of C18:3 and lower concentrations of C18:2 than grain fed beef . The off-flavor of grass fed beef was attributed to the oxidation of C18:3 free fatty acids. The oxidation of C18:3 produces 2, 4, 7-decatrienal, 2, 4-heptadienal and 3-hexenal. Hexenals are princi pally responsible for

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21 odors relating to grass. C 18:2 may oxidize to form 2-octe nal and 2, 4-decadienal which in large quantities can give aromatics of tallowy and cardboardy. Volatiles from the oxidation of C18:2 in small quantities may contribute to beefy flavor, while large quantities may contribute to o ff-flavor (Melton, 1990). Mottram et al. (1982) showed that the addition of adipos e tissue to lean beef does not give a proportional increase in lipid-d erived volatiles, in dicating that the intramuscular lipids are the major source of volatile components. Intramuscular lipids consist of marbling fat and structural memb rane lipids which are largely phospholipids and have a high content of unsaturated fatty acids (Macleod, 1998). These fatty acids are the primary source of carbonyl compounds of beef flavor, and the oxidation of the unsaturated fatty acids in beef lipids can re sult in off-flavor in meat (Melton, 1983). Meat lipids act as a solvent fo r the volatile compounds that accumulate during cooking of meat. Therefore, any feed source that in fluences the concentration of the flavor precursors should affect the flavor of cooked meat (Melton, 1990). The long-chain PUFA become oxidized during cooking and storage and may contribute to increased intens ity of undesirable flavors in beef such as milky, grassy, fishy (Melton, 1982) and warmed-over fla vors (Reineccius, 1979). The thermal oxidation of lipids gives a wide range of a liphatic products, includi ng both saturated and unsaturated hydrocarbons, alcoho ls, aldehydes, ketones, acids and esters (Farmer, 1994). Polyunsaturated fatty acids are much more susceptible to oxidation than monounsaturated or saturated fatty acids and some of the ke y odor impact compounds in meat are derived from polyunsaturated fatty acids (Farmer, 1994). Phospholipids have a high level of unsaturation and are therefor e particularly vulnerable to oxidation (Farmer, 1994).

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22 Compared with grass-fed beef, phospholipids fr om grain-fed cattle contain more n-6 fatty acids and less n-3 fatty acids (Melton, 1983). Grass-fed beef has higher levels of lowmolecular-weight aldehydes (Larick and Turn er, 1990a) and some of these possess grassy aromas. These compounds arise from the th ermal oxidation of n-3 fatty acids, suggesting the balance of n-6 to n-3 fatty acids in the phospholipids is important in flavor formation (Farmer, 1994). Larick et al. (1987) reported that as days on feed increased, sensory off-flavor decreased for cattle backgrounde d on fescue, orchard or brome grasses. Cattle slaughtered directly off grass pasture had the highest incidence of off-flavors. Hydrocarbons, which are volatiles derived from lipid oxidation, decr ease with increasing time on feed, especially between days 0 to 56. Saturated and unsaturated aldehydes such as hexanal, heptanal, 2-nonenal, 2, 4-decadiena l and decanal were also identified as major volatiles found in cooked beef samples. Ho wever, these compounds were not influenced by feeding system. Heptanoic, octanoic, nonanoic and decanoic acids, derivatives of PUFA’s by thermal oxidation, were all found to be highly correlated with grassy flavor in steaks. Larick and Turner (1990a) examin ed volatile profiles from ground beef samples processed from grass and then concentrate fed heifers. Straight a nd branched saturated and unsaturated aldehydes were among the ma jor volatiles present. The formation of alkanals, alk-2-enals and alk-2, 4-dienals, which are a class of aldehydes, were also noted and attributed to the thermal oxidation of fats . Methyl ketones were also present and are aromatics that were found in grass fed samp les. This class of compounds have been reported to give a perfume and rancid smell that effect fla vor perception. Methyl ketones are formed by the autooxidation of fatty acid s, particularly C18 unsaturates. Aromatic

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23 peaks did not differ depending on the type of grass fed. Alkanals were the compound that varied the most with time on feed, incr easing from 0 to 56 days on feed. However, no compounds were identified that positively corr elated to the off-flavors noted in heifers that were slaughtered stra ight off grass pastures. Elmore et al. (2004) examined the volatiles in beef when the animal fed either grass or concentrate as a finishing diet. Longissimus fatty acid content was significantly affected by diet, especially long-chain fatty acids (C18 through C22). Fatty acids of the n-3 class were greater in grass fed beef while fatty acids of the n-6 class were greater in the concentrate fed beef. As well, n-6: n-3 and PUFA:SFA ratios were higher in concentrate fed beef samples. Sixty-nine compounds were identif ied, mainly consisting of hydrocarbons and aldehydes. Of the compoun ds identified, 22 were affected by diet. Seventeen of these compounds were identified in concentrate fed beef and 5 were found in grass fed beef. Degradation of C18:2 in concentrate fed beef caused increases in 1octen-3-ol, cis-2-octe n-1-ol, 1-pentanol, 1-hexanol, pe ntanal, hexanal and heptanal. Degradation of C18:3 in grass fed beef cau sed increases in 1-penten-3-ol and cis-2penten-1-ol. It was concl uded that compounds that differ the most between grassand concentratefed beef will most likely have the biggest effect on flavor differences. However, these beef samples were not scored by a sensory panel for fl avor or off-flavor. Raes et al. (2003) had similar findings be tween Irish and Argentine grass fed beef compared to Belgian Blue and Limousin concentrate fed beef. Of the 67 compounds identified by GC-MS methods, aldehydes we re the most common. Argentine and Irish beef contained higher concentra tions of lower molecular wei ght saturated and unsaturated aldehydes that resulted from PUFA lipid oxidation. Of the straight chain aldehydes, the

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24 alkanals of pentanal, hexanal, heptanal a nd nonanal had the highest concentration, while the unsaturated aldehydes were 2-butenal , 2-octenal, 2-nonenal, 2-decenal, 2, 4decadienal and 2-undecenal. The higher fla vor intensity describe d by the sensory panel for the Irish and Argentine beef was correlate d with increased levels of the unsaturated aldehydes. Grass-fed beef tends to be higher in n-3 fa tty acids, particularly C18:3 and higher. During oxidation, n-3 fatty acids form com pounds thought to be responsible for offflavors in grass fed beef. The most common o ff-flavors detected in grass fed beef include grassy, fishy, rancid and warmed-over. Con centrate-fed beef tends to be higher in n-6 fatty acids, especially those that are C18:2 and higher. The oxidation products from the n-6 class of fatty acids are thought to be respons ible for beefy flavor at threshold levels. At levels above threshold values, these aroma tics tend to give off-fl avor notes of tallowy, fatty, cardboard-like and stale. Aroma tics consisting of hydrocarbons, aldehydes and methyl ketones, which are all oxidation products of fatty acids, appear to affect beef (off) flavor in a dramatic fashion. Effects of Postmortem Agin g on Sensory Attributes Enzyme Systems Responsible for Tenderness During Aging Postmortem tenderization occurs primarily through proteolysis of the muscular structure starting around 12 hours postmortem (Wheeler and Koohmaraie, 1994). The first system responsible for postmortem tende rness is the calcium dependant proteases (CDP) which includes m-calpain (CDP–II) and -calpain (CDP–I) (Goll et al., 1983). CDP-I and CDP-II contribute to proteolysis, an d calpastatin is an inhibitory enzyme to CDP-I and CDP-II. The CDP system is cons idered a neutral pH system (Koohmaraie, 1995). CDP’s are responsible for the postmor tem degradation of both interand intra-

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25 myofibril protein linkages which include de smin, vinculin, titin, nebulin and possibly troponin-T (Koohmaraie, 1995). The proteolysi s of troponin-T and the appearance of a 30 kDa component are signs of postmortem ag ing by CDP enzymes (Koohmaraie, 1988). Ilian et al. (2001) reported that CDP–II was not primarily responsible for postmortem tenderization as had been previously reported, but a third calpain, CDP–III and CDP–I, were the enzymes primarily responsible. The second system responsible for postmort em tenderness is the cathepsin system. The cathepsin system is a class of lysosoma l proteases that are contained in mammalian cells and are optimally active at acidic pH levels (Goll et al., 1983; Bond and Butler, 1987). There are 13 lysosomal proteases that ha ve been identified so far, and seven are known to exist in skeletal muscle. Cathepsi ns are thought to play only a minor role in postmortem proteolysis when compared to CDP enzymes (Koohmaraie, 1988), however, five have been characterized as to which proteins they affect. Cathepsin A cleaves myosin; cathepsin B1 cleaves myosin, actin, intact myof ibrils and collagen; cathepsin D also cleaves myosin, actin and myofibrils; cathepsin H only cleaves actin and myosin; and cathepsin L, which is the smallest of the cathepsins, cleaves actin, myosin, troponinT, troponin-I, collagen and -actinin (Goll et al., 1983; Koohmaraie, 1988). Although CDP and cathepsin systems are pr imarily responsible for the tenderness achieved through postmortem aging, there are ot her factors to consider that may alter how the carcass or meat reacts to this aging. Huff-Lonergan et al. (1995) examined the effects of aging time, animal age and sex on the degradation of titin and nebulin in beef muscles. These proteins are of particular interest because Robson et al. (1991) suggested that proteolysis of key protei ns responsible for cytoskeleton structural integrity are most

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26 likely involved in postmortem tenderness. In the Huff-Lonergan study, both titin and nebulin degraded quicker (earlier days postmorte m aging) in steaks that were classified as tender vs. steaks classified as tough by WBS te sting. It was also found that age and sex class influenced the degradation of ti tin, with young steers showing more titin degradation than young bulls or old cows. T itin did, however, continue to breakdown as time postmortem increased, suggesting that it ma y be beneficial to age meat from older cow carcasses for a longer period of time than meat from young steer carcasses to obtain maximum tenderness. To examine the effects of beef breed and aging on tenderness, Wheeler et al. (1990) studied longissimus steaks from purebred Brahman, Herefo rd and reciprocal cross steers. Steaks from Brahman crosses were rated as similar in WBS and sensory tenderness to steaks from purebred Hereford steers. However, purebred Brahman cattle that were not electrically stimulated were less tender and more variable in tende rness than steaks from Herefords or reciprocal cro sses that were not electri cally stimulated. This study concluded that steaks from Brahma n cattle were inherently less tender than Herefords. In addition, Johnson et al. (1990) examined differing percentages of Angus and Brahman breeding and the impact of cathepsins B and L and CDP on tenderness of steaks aged for 1, 5 and 10 days. It was reported that one day of postmortem aging was not significant for WBS and that at five days postmortem aging sensory panelist detected no difference in tenderness. Unlike the findi ngs of Wheeler et al. (1990), steaks aged for 10 days were more tender when they were from Angus steers rather than from to Brahman cattle. CDP had no relationship with WBS, but cathepsins B and L we re negatively correlated to

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27 WBS at 10 days postmortem aging. Therefor e, Johnson et al. (1990) concluded that breed type may influence proteolytic enzyme activity. Postmortem aging is an effective mean s to produce a more tender meat product through increased proteolysis as postmortem ag ing time increases to a certain extent. When considering using postmortem aging as a method to achieve increased tenderness it may be beneficial to account for the age and br eed of the animal that the carcass or cuts were derived from. Effects of Aging on Sensory Attributes Aging is a tool commonly employed in the meats industry to improve certain sensory attributes of meat. The main effect gained by aging is an increase in tenderness, but aging may also influence juiciness a nd flavor (Jeremiah and Gibson, 2003). There are two main methods of aging: wet and dry. Wet aging is the term used to define the method of holding meat in vacuum sealed bags in refrigerated temperatures. Dry aged beef is not packaged and is kept in a temp erature and humidity controlled environment. Most meat products today are wet aged during shipment. Wet aging is beneficial because it requires less space and gives less loss in the fo rm of moisture or purge (Parrish et al., 1991). For the purposes of this review, the tw o methods will be discussed together unless otherwise specified. Miller et al. (1997) suggeste d that aging steaks of eith er USDA Choice or Select for 14 instead of 7 days would increase initial and sustained juiciness and tenderness and increase beef flavor intensity. It was conc luded that aging steaks for 14 days postmortem should be used as a processing control point for the beef industry to improve consumer acceptance. Bratcher et al. (2005) found a significant interaction between postmortem aging period and USDA quality grade. USDA Se lect steaks had signifi cant reductions in

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28 WBS values between 7 and 14 days postmorte m with no change af ter 14 days. Steaks from the upper 2/3 Choice grade had no signifi cant improvements in WBS values after 7 days postmortem aging. These findings are in agreement with Smith et al. (1978) and Mitchell et al. (1991a), who found no significan t improvements in tenderness after 10 and 7 days postmortem aging, respectively. Realini et al. (2004) reported that aging was more exte nsive in loin steaks from pasture-fed steers, which produced lower WBS values than concentrate-fed steers at 7 and 14 days postmortem. French et al. (2000) found that supplementing grass-fed steers with low levels of concentrates produced more tender longissimus steaks when compared to steaks from grass-fed or concentrate-fed steers at 2 days postmortem. No differences in WBS values were observed past two days postmortem aging. In a study by Bidner et al. (1985), no interaction was found between ag ing period and diet, so loin steaks from both forage and grain fed animals were poole d. Aged steaks had lower WBS values and increased sensory tenderness but did not show differences in sensory juiciness or flavor intensity. Sensory connective tissues also increased, meaning detectable amount of connective tissue decreased with aging. Like wise, French et al. (2001) and Sapp et al. (1999) did not find a significant interaction between postmortem aging and diet but did have similar findings to Bidner et al. (1985) when longissimus steaks were aged for 2, 7 and 14 days and for 7, 14 and 21 days, respec tively. WBS values decreased and sensory tenderness scores increased as postmortem agi ng increased for all days of both studies. French et al. (2001) also f ound that as postmortem aging increased, flavor and juiciness tended to increase but at a lower magnitude than tenderness. Sa pp et al. (1999) found that as steaks were aged for longer periods of time, juiciness and flavor tended to

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29 increase, although not significantl y. Both authors reported that increased aging for either 14 or 21 days did decrease detectable connect ive tissue and increase overall palatability. Part of the increase in tenderness could be due to the decrease in detectable connective tissues, and several resear chers reported endogenous enzymes such as CDP and cathepsins have the ability to degrade conn ective tissues (Dutson et al., 1980; Kopp and Valin, 1980-81; Wu et al., 1981a). Parrish et al. (1969) dry aged hanging beef at different temperatures (7C and 15C then at 2C) and found no differences in WBS values between treatments. It was concluded that muscles aged in the carca ss reacted differently to postmortem aging temperatures than muscles that are excised a nd aged. To support this theory, Busch et al. (1967) reported that muscles excised from th e carcass and aged for 2 days postmortem at 16C are more tender than excised muscles ag ed at 2C for 13 days postmortem. Parrish et al. (1969) also reported more desirable flavor levels at 4 days than 7 days postmortem. In a review, Melton (1983) reported more researchers found that postmortem aging increased off-flavor production in grass-fed cattle when compared to grain-fed cattle. The reason for the differences between grass and grain fed animals was concluded to be from greater oxidation products in the steaks of grass-fed cattle. Effects of Grainor ForageFeeding on Beef Collagen Content Collagen has been shown to be an importa nt factor when examining the tenderness of meat, especially in anim als of maturing age (Hill, 1966). Bailey and Shimokamaki (1971) stated that the intermolecular bonds in collagen change to a much more thermostable form with increasing maturit y. Hill (1966) also reported that collagen solubility decreased in one-quarter strength Ringer’s solution w ith increasing age. Furthermore, Bailey (1985) suggested that although collagen conten t does not change

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30 with increasing age for a given muscle, the solubility of collagen decreases as age increases (Herring et al., 1967). Increases in protein accretion and muscle size, as shown by longissimus muscle area for animals on a high nut ritional plane (McC lain, 1977), have been related to increases in collagen solubil ity but not total collagen content (Wu et al., 1981b; Boleman et al., 1996). Aberle et al. ( 1981) concluded that cattle fed high-energy diets experience rapid rates of protein synthesis and theref ore would be expected to produce beef with a high proportion of ne wly synthesized, heat-liable collagen. However, Bailey (1985) argued that old collagen is not completely catabolized and resynthesized, but for the most part is reta ined and pushed apart to allow expansion by egress of newly synthesized collagen into tissues. To examine collagen content, French et al. (2001) fed steers si x diets of grass, concentrate or combinations of the two in order to alter nutriti onal planes. Although a direct measurement of collagen was not take n, sensory panelists were asked to rate “chewiness”, a descriptive term used to assess the perceived connectiv e tissue in a sample along with tenderness for longissimus samples. Regardless of diet, no difference in “chewiness” between meat samples was reported. Differences may not have been observed because the forage fed to the steers was of high quality a nd possibly contributed to similar lean accretion rates. Wu et al . (1981b) slaughtered animals after grazing on Kansas flint hill pasture, pasture follow ed by concentrate feeding for 120 day, or concentrate feeding for 126 days (treatment s 1, 2 and 3, respectively). Although total collagen was not different between treatme nts, salt soluble collagen increased for treatments 2 and 3 in the longissimus muscle and acid soluble collagen increased for the steers in the second treatment. This coinci des with similar magnitude increases for

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31 longissimus muscle areas. Bodwell and McClai n (1971) reported that salt soluble collagen is newly synthesized collagen, while acid soluble collagen is young collagen that is metabolically older th an salt soluble colla gen. Hydroxyproline excretion is related to collagen turnover and the synthesis of new collagen formation (Kivirikko, 1970). Wu et al. (1981b) also reported th at when animals were taken from low to high planes of nutrition, plasma concentration of nonprot ein hydroxyproline incr eased, showing an increase in immature collagen synthesis as the nutritional plane increased. Hydroxyproline is an important structural component of collagen and is used during quantification of total, soluble and insol uble collagen contents (Bergman and Loxley, 1963; Hill, 1966; Cross et al., 1973; Dugan et al., 2000) As an animal matures, percentage of soluble collagen decr eases and number of intermolecular collagen crosslinks increase (S mith and Judge, 1991). However, Miller et al. (1983) concluded that ther e was no difference in percen t soluble collagen for youthful steers (A and B maturity) compared to matu re steers (C and D maturity) when both maturity groups were fed a high plane of nut rition. However, mature steers did have significantly more total collagen than youthful steers. This difference, however, did not correlate to a significant difference in sens ory panel overall tenderness scores. While the values for total collagen and soluble collagen found by Miller et al. (1983) were higher than other published findings, the trends were similar to other reports. To investigate the effects of nutritional plane on co llagen content of mature cows (10 years of age), Miller et al. (1987) fed two groups: Gr oup 1 were fed ad-libitum of a high quality diet while Group 2 were on a restricted or maintena nce diet. Increased dietary energy simultaneously increased the amount and propor tion of newly synthesized heat liable

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32 collagen and decreased the amount of insolubl e collagen. No change in total collagen content was observed. Boleman et al. (1996) showed that as tim e cull cows spent on a concentrate diet increased (from 0 to 84 days), the percent of total collagen that is heat liable also increased up to day 56. The increase in pe rcent soluble collagen is related to numeric (although not significant) increase s in total collagen. This would suggest that through increased concentrate feeding structural cha nges in collagen will occur in animals of advanced maturity. Cranwell et al. (1996a) al so reported that cull cows fed a concentrate diet for 28 days exhibited more soluble coll agen and an increase in the proportion of soluble to insoluble collagen. No further in creases in soluble collagen were gained by feeding animals past 28 days. The increase in soluble collagen realized is attributed to the increase in lean gains as time fed increased for the same cows reported by Cranwell et al. (1996b). Etherington (1987) stated newly synthesized collagen would have fewer stabilized crosslinks and should be more heat labile. In support of this, Light and Bailey (1979) found that during collagen synthe sis, aldimine-type bonds form between tropocollagen molecules and provide reducible, h eat labile crosslinks which contribute to the organization and structural stability of collagen fibers. Effects of Grainor ForageFeed ing on Cook and Thaw Loss Characteristics Thaw and cook losses are important attribut es to consider wh en evaluating steaks or muscles. Just as fat is inversely related to moisture content and can provide some insurance that a steak will be juicy after cooking, water loss du ring thawing and cooking may also impact the overall acceptability of a steak. Cook and thaw loss (sometimes combined) are widely reported in the literatur e (Miller et al., 1987; French et al., 2001; Baublits et al., 2006). However, scarce inform ation is published relating to the direct

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33 causes of cook and thaw loss and their impact meat palatability. Marsh (1977a) stated there were only two factors to be considered when examining the variability of meat tenderness: 1) the collagen component of connective tissue, and 2) differences in contractile proteins. Although these two f acets of meat are important to the overall quality and tenderness of meat, it is reasona ble to postulate that cook and thaw losses might contribute to this variation. Jeremiah (1978) proposed the cooking pr operties of muscles exert important influences on beef palatability and consumer acceptance. Researching extraneous effects on thaw and cook loss led Wheeler et al. (1996) to report that thaw temperature did not have a significant effect on co mbined thaw and cook losses when steaks were thawed at 2, 6 or 12C. However, as thaw temperat ure increased WBS value decreased. Other extraneous effects examined by Wheeler et al. (1996) included cooking to a constant temperature or for a constant time, oven broi ling vs. grill broiling and grill broiling vs. grill broiling and holding. Cooking to a consta nt temperature rather than for a constant time, grill broiling rather than oven broiling and broiling then holding rather than grill broiling only all increased the amount of c ook loss that was observed. Likewise, WBS values increased with increased cooking loss in all experiments except for oven broiling vs. grill broiling. In this case, no difference in WBS was observed. It was concluded that cooking loss had an effect on meat tenderness, but this effect was confounded with lower thaw temperatures for the grill broiling vs. grill broiling and holding experiment. Intrinsic factors also affect thaw and cook losses. Po sitive correlations have been reported for moisture content and thaw loss and total cooki ng losses. Chemical fat analysis showed that as fat increased , thaw and cooking losses both decreased.

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34 Correspondingly, connective tissues affect thaw and cook losses. Muscles containing greater amounts of soluble and total hydroxypro line sustain decreased thaw losses, while cuts containing increased amounts of insolubl e and total hydroxyprolin e sustain increased cooking losses (Jeremiah et al., 2003). Br atcher et al. (2005) concluded that USDA Select grade steaks had increased cooking losses compared to USDA Choice grade steaks. When the interaction of USDA grade and days of postmortem aging was examined, steaks from USDA Choice carcasse s also had lower thaw losses than USDA Select carcasses until 28 days of postmorte m aging was reached. Since USDA Choice carcasses have increased intramuscular fat compared to USDA Select carcasses this conclusion is supported by earlier findings th at total cooking losses decrease as fat composition increases. To examine cook and thaw loss, Jeremi ah et al. (2003) conducted extensive research on 33 different cuts of beef. All b eef cuts were allowed to thaw for 72 hours at 4C and were roasted to an internal temper ature of 72C. There was a vast amount of variation in thaw loss, ranging from 1.26 to 10.05%, and cook loss, ranging from 21.51 to 33.26%. No significant differences were observed relating musc le location in the carcass to thaw or cook losses. These findings are s upported by other authors that have reported large variations between and among muscles from the beef carca ss (Paul and McLean, 1946; Rhee et al., 2004). However, Crouse et al. (1984) reported no differences in thaw or cook loss when data was pooled over three muscles. There were also no differences observed in WBS value, sensory tenderness or sensory juiciness. These results could be confounded by the effects of anim al diet (grain vs. grass). Crouse et al. (1984) showed

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35 that grain fed heifers were c ooked to greater degree of donene ss than were grass finished heifers. French et al. (2000) and Fren ch et al. (2001) bot h reported that regardless if steers were finished on low quality forages, high quality forages or concentrates, total cook losses were not affected by di et but were affected by tim e of postmortem aging. As postmortem aging increased, cook loss also increa sed. This is similar to the conclusions of Bratcher et al. (2005) for the interaction of USDA Grade and postmortem aging period. However, Miller et al. (1987) found no differences in total longissimus cook losses between mature cows fed either a high energy or low ener gy diet, even though differences were found in soluble an d insoluble collagen content. Baublits et al. (2006) reported no signifi cant difference in total longissimus cook loss for meat from steers that were grazing fe scue pasture, fescue pasture supplemented with soy hulls or orchard grass pasture suppl emented with soy hulls. Sapp et al. (1999) also reported no differences in cook loss for steers fed pasture, pasture with concentrate or concentrate only. However, differences in thaw losses were detected and decreased from pasture to pasture with grain to grai n only. Although there we re no differences in cook loss, thaw losses were attributed to the hi gher moisture content of pasture fed steers. It is not readily unde rstood why no differences were f ound for cooking losses for animals on differing nutritional planes. In all studies discussed, mois ture content was higher for pasture fed animals and fat composition was higher for concentrate fed animals. Expected results would have been to see increased cook loss with increased moisture content when steaks are cooked to a constant in ternal temperature. Miller et al. (1987), Sapp et al. (1999) and Baublits et al. (2006) all reported cook ing steaks to an internal

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36 temperature of 70C. However, error doe s commonly exist between steaks and some steaks are inadvertently cooked to higher internal temperature. This error could affect differences between treatments, especially if larger standard errors are reported. As internal temperature increases during cooki ng, cook losses significan tly increase if all other variables are held constant. Wheeler et al. (1999) showed that as internal cooking temperature was increased from 60C to 80C, cooking losses increased. There are numerous intrinsic and extrinsic variables and interactions that can affect thaw and cook losses. Most notable of these are mo isture and fat composition, internal cook temperature, time of cooking and method of pr eparation. Consistency in preparation is the best way to ensure a reduction in e rror when measuring cooking characteristics (AMSA, 1995). Effects of Grainor ForageFeed ing on Muscles and Lean, Fat and Bone Composition Calculating and estimating lean muscle, total lean proportion , total fat proportion and total bone proportion is an important tool in the meats industry. Many animals such as cull cows, are sold based upon percent lean. Other animals, such as fed steers, can be sold based on the estimated amount of fat and percent of boneless closely trimmed retail cuts (BCTRC) produced from the carcass. Co mposition analysis allows the industry to test animals in a population in order to measure traits such as percen t lean and percent fat of a carcass. There are many ways to dete rmine carcass composition. The most accurate method to determine total composition of a meat animal is to perform a chemical analysis of the entire body after slaughter , including the digestiv e tract and bladder. The next best method would be to analyze the dressed carcass (Hankins and Howe, 1946). The problem with these two methods is that they are very costly and time consuming. In

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37 addition, they leave no utilizable portion of th e carcass to recupera te cost. For these reasons, more efficient methods for dete rmining carcass composition have been researched. To determine which section of the carcass could be removed for best estimation of total carcass composition, Hankins and Howe (1946) conducted a review of early research. In this review, they reported th at Lush (1926) found the wholesale rib (6 – 12th rib section) to be a relatively accurate predictor of total carcass fat composition. However, this method required the use of the en tire rib section, one of the most valuable areas in the beef carcass. Hopper (1944) compared the w holesale rib with the 9-10-11th rib section of the carcass and found that they were highly correlated for edible portions. This research led Hankins and Howe (1946) to further investigate the use of the 9-10-11th rib portion as an indicator for total carca ss composition including fat, lean and bone proportions. They later reported that the 9-10-11th rib section was a good indicator of total carcass composition and could be use d, therefore causing the least amount of damage to the carcass. The method of determining carcass composition by 9-10-11th rib dissection, although accurate, is still an invasive procedure that cause s irreversible damage to a valuable cut of the carcass. Johnson and R ogers (1997) reported on methods to predict yield and composition of mature non-fed cow carcass by the use of regression equations. Typically, cow carcasses are not ribbed at the 12-13th rib juncture because they are predominantly sold on a lean tissue basis. However, a cow carcass of good condition and moderate maturity (B or C) may be ribbed and graded as is done with youthful fed carcasses. Therefore, Johnson and Rogers (1997) used carcass measurements and

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38 regression equations to pred ict composition for both ribbed and non-ribbed mature cow carcasses. Best fit equations for ribbed ma ture cow carcasses included the measurements of hot carcass weight (HCW), adjusted pr eliminary yield grade (APYG) and marbling (MARB) to predict fat proportion. Hot carca ss weight, APYG, longissimus muscle area (LMA) and MARB were used to predict the prop ortion of bone and carcass fat free lean in the carcass. For mature cow carcass that were not ribbed, measurements included HCW, APYG, and APYG2 for proportion fat; APYG and carcass confirmation (CONF) for proportion of bone and HCW, APYG, APYG2 and CONF for proportion carcass fat free lean. However, as carcass characterist ics change due to production and management practices, prediction equations may have to be altered in order to more accurately estimate composition (Hedrick, 1983). O’Mara et al. (1998) also reported predic tion equations for es timation of mature cow carcass composition. However, this st udy derived regression equations for both carcass and live animal characteristics. Traits and R2 values for estimating carcass composition were very similar to those of Johnson and Rogers (1997), with the exception of the use of kidney, pelvic and heart fat in the equations. As well, the O’Mara et al. (1998) equations were devised to calculate proportion of car cass lean and fat but do not include estimation equations for proportion of bone in the carcass. Best fit equations for estimating carcass composition with traits for proportion of fat and lean had R2 values of .83 and .82, respectively, and used the traits of live preliminary yield grade, live condition score, live muscle score and live weight. Although the live equations suggested by O’Mara et al. (1998) do not pr edict composition as accurately as the carcass

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39 composition equations suggested by Johnson and Rogers (1997), they can still provide a fairly accurate prediction of sla ughter cow composition. To determine feeding effects on percent fa t and bone, Bowling et al. (1978) and Brown and Johnson (1991) conducted studies on steers and cows, respectively. Bowling et al. (1978) fed diets of gra ss, grass with concentrate or concentrate only while Brown and Johnson (1991) fed high energy supplemen ts. In both studies, percent lean decreased, percent fat increased and percent bone decreased for animals on higher nutritional planes or as time on concentrate increased. Although pe rcent lean decreased, protein produced by the carcass and protein per day of age bot h increased linearly as time on feed increased, thus indicating that cha nges in proportion of carcass composition were due not only to increased fat levels but that protein accretion was also occurring (Bowling et al., 1978). Schroeder et al. (1980) and Schaake et al . (1993) both reported similar findings to Bowling et al. (1978) when comp aring steers on differing nutritional planes. Hedrick et al. (1981) concluded that as yi eld grade and quality grade increased, carcass weight and percent fat trim increased while perc ent of total retail cu ts and percent of bone from the carcass decreased. Likewise, Hedrick et al. (1983) reported that if steers were finished on grass, grain or a combination of grain with roughage, primal retail cuts and total retail cuts as a percent of carcass wei ght were highest for grass finished steers. However, there was little change in percen t retail cuts on a live weight basis across treatments. Dryden et al. (1979) concluded that age of cow (3 – 10 years of age) did not effect muscle weight or percent of wholesale cut for major muscles of the chuck, round, shortloin or sirloin butt. Ho wever, when cull cows were fed for 0, 42 or 84 days, weight

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40 of the 0.0 cm fat trim m. Biceps femoris and m. Semitendinosus increased (Matulis et al., 1987; Faulkner et al., 1989). Fa ulkner et al. (1989) and Bo leman et al. (1996) also fed cows from 0 to 84 days. Both researchers in dicated that with increased time on feed cull cows would increase in soft tissue weight (lean and fat) wh ile maintaining bone weight. It was suggested that past a certain point, increased weights of realimented cull cows could be due to increased proportions of fat be ing deposited instead of lean. Matulis et al. (1987) fed cull cows a concentrate di et for 0, 28, 56 and 84 days and found that percent soft tissue fat increased with time on feed. However, when compositional weights were examined, the largest increase in carcass fat weight occurred from days 0 to 28. Although fat weight conti nued to increase with time on feed, the amount of fat accretion was less than the previ ous feeding period. Weight of lean also increased with increasing days on feed; however, unlike fat co mposition weights, the increases in lean remained constant to the previous feeding pe riod and showed that lean accretion still occurred at 84 days on feed. As cull cows ar e realimented, it is expected that they would increase in body condition score (BCS). A pple (1999), Apple et al. (1999a) and Apple et al. (1999b) studied the effects of increasi ng BCS on cull cow value, cull cow by-product yield and value and cull cow subprimal yields , respectively. They concluded that cull cows in moderate condition (BCS 6 or 7) we re of the most value live and carcass. Although cows in moderate condition produced more fat trim than lower conditioned cows, which had the highest drop credit, the in crease in muscle weight and quality grade of moderate conditioned cows was great enough to compensate for the price differences.

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41 Effects of Grainor ForageFeeding on Factors Affecting Quality and Yield Grade Quality Grade Factors Quality grade is a standard measurement system regulated by the USDA to ensure animals are justly segregated into like groups for traits that influen ce overall palatability. Although not a perfect system, many animal s and carcasses are sold on estimated or measured traits that are based on perceived quality grade ranking. The two main traits that determine quality grade are marbling (intramuscular fat) and maturity (the combination of lean maturity and bone matur ity). Other factors that influence quality grade are lean color (discussed in a later se ction), lean texture, lean firmness and sex class (USDA, 1997). This review herein wi ll examine how feeding forages and grains may impact quality grade. For a more detail ed explanation of determining quality grade, see the Meat Evaluation Handbook (AMSA, 2001). Young cattle are typically fed a concentrate diet to increas e the growth rate of the animal so that it is “finished” at an early chronological and physiologi cal age. One of the primary aspects in determining the “finish” of an animal is the amount of fat, and therefore the perceived amount of marbling, the carcass will have. External fat thickness has been shown to be correlated to marb ling (Wilson et al. 1993; Koots et al., 1994; Stelzleni et al., 2003). Consum er sensory panels have shown that as carcass marbling increases, the probability of producing an acceptable product in terms of palatability increases as well (Platter et al., 2003). Wu et al. (1981b) reported that in steers fed grass, grain or grass with grain there was no effect on maturity score (all animals were of A30 maturity). However, grass fed steers ha d the lowest marbling scores and therefore received the lowest quality gr ade. Animals fed a combination of grass with concentrate had the most marbling and were assigned the be st quality grade of lo w choice. Crouse et

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42 al. (1984) also reported that heifers fed a gra ss or grain diet to similar fat thickness had different quality grades. Grai n fed heifers had more marbling, firmer lean, finer textured lean and were scored more youthful for lean maturity. Although bone and overall maturity were not different, bone maturity wa s numerically higher in the grain fed heifers and overall maturity was numerically lowe r. These differences accounted for a difference in quality grades of Good averag e for grass fed heifers (modern day Select with slight60 degree of marbling) and low Choice for grain fed heifers. Schaake et al. (1993) also reported A-maturity steers had in creased marbling scores and firmer lean, leading to increased quality grades for steers fed concentrate vs. fescue-clover pasture. In youthful animals, there are quality grade be nefits associated w ith finishing cattle on concentrates rather than forage, but there is some question if thes e positive effects would be carried over to cull cows fed a concentrate diet prior to slaughter. Hilton et al. (1998) summarized that an incr ease in cull cow maturity is associated with a decrease in palatability traits, and the current USDA quality grading system does not readily equate to differences in cull cow palatability. However, if cull cows are fed concentrates prior to slaught er, it may be possible to posit ively alter traits used to measure palatability via quali ty grading. Apple (1999) repor ted that as BCS increased, percent of cull cow carcasses grading U.S. Utility increased linearly while the percent of carcasses grading U.S. Cutter decreased linearly . This demonstrated that increasing BCS can improve cull cow quality grade. Matulis et al. (1987) reported that marbling scores increased for cull cows when fed for 28 to 56 days and lean maturity scores decreased after 56 days of concentrate feed ing, leading to an increase in quality grad e after 56 days on a concentrate diet. Faulkner et al. (1989) concluded that lean maturity decreased

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43 significantly between 0 and 42 days on feed. Although bone maturity was not different for 0, 42 and 84 days on feed, marbling scores increased from traces at day 0 to modest by day 84, resulting in an increase in quality grade. Miller et al . (1987) and Brown and Johnson (1991) reported that increasing ener gy in a cull cow diet can increase final quality grade by improving the marbling score, lean maturity (Mille r et al., 1987), lean firmness (Brown and Johnson, 1991) and overall ma turity (Miller et al., 1987). Boleman et al. (1996) and Cranwe ll et al. (1996b) concluded that quality grade can be improved in realimented cull cows by improving marbling scor e, lean firmness, lean texture and lean maturity when cull cows have at least 56 days on feed. Yield Grade Factors USDA yield grade is used to estimate the boneless, closely trimmed retail cuts (BCTRC) that come from round, loin, rib and chuck of a beef carcass (Savell and Smith, 2000; AMSA, 2001). Although yield grading is typically employed for use in youthful animals (A and B maturity), it is also a be neficial tool when taking measurements on older animals, such as cull cows, when envi ronmental changes have been made. Even though cull cows are primarily sold based upon the percent lean of the carcass, it is advantageous to know how much of the ca rcass can be manufactured into BCTRC. Much like quality grade, there are many fact ors that have to be considered when estimating yield grades of cattle. The most influential measurement in estimating yield grade (YG) is 12th rib fat thickness (FOE). This measurement may be adjusted (APYG) in order to better estimate carcass fatness. Other factors to consid er are ribeye area (REA), percent kidney, pelvic and heart fat (KPH) and liv e or carcass weight of the animal (Savell and Smith, 2000; AMSA, 2001). Dressing percent (DP) and average daily gains (ADG) are also factors th at can indirectly influence yi eld grade determination. As

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44 discussed in the earlier section on carca ss composition, bone weight tends to stay constant while fat and lean weights tend to increase. Therefore, increases in DP and ADG are assumed to be attributed to an increas e of lean and fat and will directly affect yield grade. Bennett et al. (1995) reported crossbred st eers fed on concentrate diets to similar final live weights had increased ADG and spent less time on finishing diet than crossbred steers fed a forage diet. Concentrate fe d steers also had increased HCW and DP. Although concentrate fed steers had more FOE, they also had larger REA and similar KPH, leading to a similar final YG. Schroe der et al. (1980) presented similar findings with the exception that the increase in FOE was great enough to increase YG in concentrate fed steers compared to that of fo rage finished steers. However, steers fed concentrates had yield grades that were cons idered acceptable. Bi dner et al. (1986) also reported that when steers were started and finished at the sa me weights, concentrate fed steers had higher ADG than forage fed steers. HCW was similar betw een the two groups, but concentrate fed steers had an increase in FOE and KPH which could have led to an increased DP. Although concentrate fed steer s were reported to have a significantly higher yield grade, both carcass groups were of acceptable USDA yield grade 2. However, Bidner et al. (1985) reported that wh en steers were slaughter ed at similar days of age, grain fed steers had increased ADG, fi nal live weight and HCW. Grain fed steers also had increased REA, but the increased di fference in FOE of grain finished steers meant a significantly higher USDA yield grade of 3.9 when compared to 2.1 for forage fed steers. Animals with USDA yield grades of 4 or greater may receive a discount at purchasing due to lower return of BCTRC.

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45 Miller et al. (1987) found th at realimentation of cull co ws on a high energy diet increased ADG over a low energy, maintenan ce diet. Realimentation had no effect on live weight but did increase HCW and REA by almost 10 cm2 over cull cows that received the low energy diet. Realimentati on also increased KPH and FOE significantly, resulting in an YG of 3.4 compared to 2.0 fo r cows on the low energy diet. Boleman et al. (1996) also reported an increase in YG fo r cull cows realimented for 0 to 84 days. Although there was a linear in crease in live weight, FO E, HCW and REA did not increase past 56 days on feed. Yield grade was similar from 0 to 56 days and increased significantly only after 84 days on feed. Howe ver, even after 84 days on feed, the yield grade was reported as 1.5 with .99 cm FOE. In the case of Boleman et al. (1996), optimal carcass characteristics for yield grade and effi ciency may have been attained by 56 days on feed, even though cows fed for 84 days were still of acceptable yield. Similarly, Matulis et al. (1987) reported cull cow car cass values would indicate maximum yield efficiency by 56 days on feed. Faulkner et al. (1989) found that cull cows realimented for either 42 or 84 days on feed had the highest increase in ADG. Howe ver, ADG decreased significantly from 42 to 84 days on feed. As well, cows became more inefficient in feed conversion between 42 and 84 days on feed. Cows fed 0 to 42 days had feed to gain ratios of 4.66 where cows fed to 84 days had nearly doubled ratios of 8.43. Cows realimented for 42 and 84 days had heavier final live weights th an non-realimented cows but were statistically similar to each other. However, cows fed to 84 days had significantly higher HCW than cows fed to 42 days, and cows fed 42 days in turn had significantly high er HCW than non-fed cows. Dressing percent followed a similar pa ttern. With carcass ch aracteristics from

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46 Faulkner et al. (1989), it is a pparent that the increase in DP from treatments of 42 and 84 days on feed were due to increases in KPH a nd FOE. Ribeye area increased from 0 to 42 days but did not increase signi ficantly past 42 days. KPH and FOE, however, increased significantly from 0 to 42 days on feed and again from 42 to 84 days on feed. Non-fed cull cows had the lowest yield grade of 1.58, while cull cows fed for 42 days had a very acceptable yield grade of 2.00. Cull cows fed fo r 84 days had a border line yield grade of 3.76. Faulkner et al. (1989) conc luded that it may be benefici al to feed cull cows for 42 but not 84 days to improve carcass characteristics. Objective and Subjective Carcass Fat and Lean Color Color is typically measured by two methods. The first method commonly used is subjective color assessment in which an indivi dual assigns a score to the fat and lean. Subjective color assessment typically uses a numeric scale were one end is associated with yellow coloration for fat or pale/light red color for lean and the other end is associated with white fat or dark purplish co lored lean. In objec tive color measurement, a chroma meter is employed and takes what is e quivalent to a snap shot of the subject. The two most commonly used forms of objectiv e measurement are Hunter Lab values or CIE L* a* b*. These two forms of color measurements work on the same scale, assigning L(*) as the lightness variable (100 = whiteness), a(*) as the redness variable (+ = redness, = greenness) and b(*) as the yellowness variable (+ = yellowness, = blueness). Hunter and CIE values assess color in a way closely representing human sensitivities to color differenc es (Minolta, 1991). However, Hunter and CIE values are not interchangeable as Hunter values are qu adratic functions and CIE values are cubic functions (Minolta, 1991; Murray, 1995).

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47 Color perception plays a major role in the evaluation of meat quality, as consumers use color as an indicator of fr eshness (Lanari et al., 2002). Lean meat that is too pale or too dark and fat that is too yellow are perceive d as quality defects. Consumers in certain regions of the world tend to associate yello w fat with old or dis eased cattle (Dikeman, 1990). Numerous variables may alter the color of lean and fat in a beef carcass. Age, myoglobin content, pH and carot ene content are all factors th at may affect lean and fat color in pasture or gr ain finished cattle. Carcass Fat Color Hilton et al. (1998) reported fat color b ecame more intensely yellow as carcasses increased in maturity. Carcasses of A-matur ity had subjective fat color scores of white while E-maturity carcasses had scores of moderate yellow. However, some of the carcasses in the older maturitie s were assumed to be from cattle fed on high plane of nutrition, which can alter fat pigmentation to a whiter color. Yang et al. (1992) concluded cattle can absorb carotenoids from their diet and deposit them into adipose tissues, therefore giving the fa t a yellow pigmentation. Sinc e grains tend to have lower concentrations of carotenoids compared to mo st forages, increasing the duration of grain feeding can decrease the yellow pigmentation of fat in cattle previously fed forages (Walker et al., 1990; Strachan et al., 1993). As well, French et al. (2000) suggested that whitening of fat is due to a dilution effect of new fat being deposited that has less carotene in it. In a review, Muir et al. (1998a) reported that in four of the nine experiments reviewed, grain feeding show ed a significant reduction in the yellow pigmentation of carcass fat. In the National Market Cow and Bull Qu ality Audit – 1999, Roeber et al. (2001) reported fat was deemed too yellow in 30.8 pe rcent of the carcasses surveyed. Although

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48 this number is down from the 1994 survey (N CA, 1994) levels of 41.0%, it is still adding up to $6.48 of unrealized value per head sla ughtered (NCBA, 1999). Mu ir et al. (1998b) reported differing results for two experiments. In the first experiment, 3 year old steers were fed a diet consisting of 70% maize and 30 % pasture silage or pasture only for up to 14 weeks. In the second experiment, 3 year old steers were fed a di et consisting of 70% barley and 30% pasture silage or pasture only for up to 16 weeks. The first study showed that diet did not have a signi ficant effect on fat color. However, the second study showed that concentrate/silage fed steer carcasses ha d a brighter whiter fat color. Brown and Johnson (1991), Boleman et al. (1996) and Cr anwell et al. (1996b) al l reported cull cow carcass fat color to become whiter as time on concentrate or high energy supplement increased. Similarly, Bidner et al. (1985), Bidner et al. (1986), Sch aake et al. (1993) and Bennett et al. (1995) reported whiter fat co lor when young steers were fed a concentrate instead of pasture or forage. Carcass Lean Color Lean color is a very important quality attribute for consumers when deciding to purchase a beef product. Beef that is not a bright, attractiv e color is often perceived by consumers to be unfresh, unwholesome, or from an old animal (Dikeman, 1990). Many factors contribute to lean beef color. Th e first of these is myoglobin, which is the precursor color of meat. On exposure to ai r, myoglobin oxidizes to form a bright red pigment known as oxymyoglobin, which is attrac tive to consumers and associated with perceived freshness (Muir et al., 1998a). Alt hough beef color is hi ghly attributed to myoglobin, which increases with age (Bowling et al., 1978) to form darker colored lean, color is also affected by the actions of oxidation and pH. When oxymyoglobin further oxidizes to form metmyoglobin, a brown colo r is produced. Metmyoglobin formation is

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49 affected by chemically reducing conditions such as pH (Renerre and Labas, 1987). Myoglobin content may also be related to diet in that higher concentrations have been reported for grazing animals compared to feed lot animals. This environmental difference may result in more physical exercising of the muscles which would result in darker colored beef (Varnam and Sutherland 1995). Lanari et al. (2002) reported that carcass lean from pa sture fed steers was darker than carcass lean from concen trate fed steers. However, th ey concluded this difference was not due to pigment concentration b ecause myoglobin concentrations were not different between treatments. Although pH was not taken in the Lanari et al. (2002) study, the darker lean color may have been cau sed by an increase in pH. Bowling et al. (1977) suggested that grainfed cattle are less susceptibl e to high pH because they become more accustomed to people and pens while in the feedlot. If this is true, the increased pH due to stress in grass-fed cattle may increase water holding capacity (Lawrie, 1979) and cause a darker lean app earance. This theory can be supported by the results of Muir et al. (1998b), who reported higher pH values and darker lean color for forage-fed beef when compared to grain-fe d beef. As well, Schroeder et al. (1980) reported that grain-fed beef were of greater maturity than forage -fed beef but still possessed brighter and more youthful appearing lean. Cranwell et al. (1996a) reporte d that cull cow lean color did not change with 28 days on a concentrate diet but did become si gnificantly lighter and more cherry red after 56 days. Miller et al. (1987) reported that after 84 days on a high energy diet, mature cows had a lighter, brighter lean color th an cows receiving a maintenance diet. Additionally, Boleman et al. (1996) reported the most significant improvement in lean

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50 color of cull cows receiving concentrate diet s occurred after 56 days on feed. It is apparent that feeding concentrates can improve lean color of beef, even in older animals and animals that had previously been on fora ge based diets. However, the effects of concentrate feeding may not be apparent until after several weeks of feeding and may be more related to pH differences th an myoglobin content differences.

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51 CHAPTER 3 BENCHMARKING CARCASS CHARAC TERISTICS AND MUSCLES FOR WARNER-BRATZLER SHEAR FORCE AND SENSORY ATTRIBUTES FROM COMMERCIALLY AVAILABLE BEEF A ND DAIRY CULL CO W CARCASSES Introduction Cows are culled for various reasons incl uding advancing age, poor performance and failure to reproduce. Most cull cow car casses have a high percent lean and little external fat making most of the meat obtained from them destined for lean trimmings and ground beef production. Although cull cows are primarily a by-product of an industry dedicated to producing grain-fed A-maturity be ef (Cranwell et al., 1996a), they are still a valuable resource to producers and account fo r 15-20% of total revenues (Sawyer et al., 2004). As well, cull cows are equally important to the domestic beef supply. Approximately 5.1 million head of cull beef a nd dairy cows entered the slaughter market in 2004, accounting for almost 13% of domes tically produced beef (USDA, 2005). The 1994 National Non-Fed Beef Qual ity Audit (NCA, 1994) and the 1999 National Market Cow and Bull Quality Aud it (NCBA, 1999, Roeber et al., 2001) outlined several problems with the current status of cull cows entering the slaughter market. Several of the problems listed in the quality a udits included carcasses with low weights, light muscling scores, low quality grades and yellow fat. These defects were estimated to cause producers to lose approximately $26.50 in unrealized profits in 1999. It has also been shown that tenderness tends to decrease with increasing age and that yellow fat in market cows is associated with a decrease in tenderness and an incr ease in off-flavors

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52 (Hilton et al., 1998). Many of the defects outlin ed in the previous audits could possibly be minimized by increasing the nutritional plane of cull cows prior to slaughter. Several researchers have shown that incr easing the nutritional plane of cull cows through supplementation prior to slaughter has improved carcass char acteristics (Brown and Johnson, 1991) and tenderness (Miller et al., 1987). Others have examined the effects of short term realimentation or concentrate feeding on cull cow carcass characteristics and quality traits. Short term feeding has also been shown to favorably impact carcass characteristics, tenderness and sensory attri butes (Matulis et al., 1987; Boleman et al., 1996, Cranwell et al., 1996a). However, most of current realimentation research focuses on the sensory at tributes and te nderness of the Longissimus dorsi , which along with the Psoas major, are commonly removed for further processing due to their increased value. Very little is known about muscles from older maturity cow carcasses and how production practices may influence thei r palatability. With alternative protein sources becoming more economical and popular , the beef industry needs to explore intermediately priced, yet tende r and palatable options to comp ete for market share. If muscles from the chuck and round from realimen ted cull cows are comparable to the loin in tenderness and sensory charac teristics, it may be advantageous to examine their use as an intermediately priced beef option. Cows are typically segregated prior to slaughter by plant personnel based upon perceived quality and cutability. Cull cows that are of increased condition (6+) and perceived to have been fed a higher quality ration prior to slaughter are separated from those that have not due to the potential in creased value of thei r carcass (Apple et al., 1999b). However, there is no current research examining how commer cially identified

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53 fed (increased plan of nutri tion prior to slaughter) and non-fed (cows that were not fed supplemental energy prior to slaughter) b eef and dairy cull co w carcasses differ in carcass characteristics or palatability and how they compare to A-maturity beef. Therefore, it is the objective of this resear ch to benchmark the car cass characteristics and muscle tenderness and sensory attributes of commercially identified fed and non-fed beef and dairy cull cow carcasses and to compare them to USDA Select A-maturity beef. It is hypothesized that fed beef and dairy cull cows will have a more desirable carcass and their muscles will have improved sensory char acteristics than non-fed cull cows, making them viable as an intermed iately priced beef option. Materials and Methods Carcass Selection Seventy-five carcasses were randomly sele cted from 5 groups of slaughter cattle commercially identified by trained plant personn el as beef non-fed (B-NF), beef fed (BF), dairy non-fed (D-NF), dairy fed (D-F) a nd concentrate fed A-maturity USDA Select (SEL) steers (n = 15 each group) from P ackerland Pack (Greenbay, WI). Cows commercially identified as non-fed are cows th at were perceived to be fed maintenance diets without supplemental ener gy. Cows commercially identif ied as fed are those that are perceived to be fed supplemental energy pr ior to slaughter base d upon live condition. Upon carcass selection, carcasses we re ribbed between the 12 – 13th rib junction and allowed to bloom for approximately 30 mi nutes. After blooming, carcass data was collected including: hot carcass weig ht (HCW), ribeye area (REA), 12th rib fat thickness over the ribeye (FOE), prelim inary yield grade (PYG), lean maturity (LM), bone maturity (BM), subjective lean color (LC), subjective fat color (FC), marbling score (MARB) and muscle score (MUS). Percent lean (PL) was calculated from carcass characteristics for

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54 all groups and carcass composition was calcula ted by the ribbed carcass equations of Johnson and Rogers (1997). After a 24 hour chill, designated carcasses were separated into primal cuts by trained plant personnel. Muscle s of interest were then excised from the chuck, loin and round. Muscles excised included m. Infraspinatus (INF), m. Triceps brachii – lateral head (LAT), m. Triceps brachii – long head (LON) and m. Teres major (TEM) from the chuck; m. Longissimus dorsi (LOD) and m. Psoas major (PSO) from the loin; and m. Gluteus medius (GLM), m. Rectus femoris (REF) and m. Tensor fasciae latae (TFL) from the sirloin and round. Muscles were vacuum pa ckaged and shipped to the University of Florida Meats Processing Center (Gainesville, FL). At the University of Florida Meats Processing Center, steaks were cut to 2.54 cm thickness across the grain from the posterior end of the muscle before being vacu um packaged and stored at 2C then frozen at -40C on day 14 postmortem. Warner-Bratzler Shear Force Steaks from each muscle designated for Wa rner-Bratzler shear force (WBS) were thawed for 18 hours at 4C. Steaks were then cooked on Farberware Open-Hearth Broilers (Farberware Products, Nashville, TN) that were preheated for 20 min. Steaks were turned once when the internal temperat ure reached 35C and then were allowed to finish cooking until they reached an inte rnal temperature of 71C (AMSA, 1995). Internal temperatures were monitored by c onstantan thermocouples (Omega Engineering, Inc., Stamford, CT) placed in the geometric center of each steak and recorded using a 1100 Labtech Notebook for Windows 1998 (Computer Boards, Inc., Middleboro, MA). Steaks were then allowed to cool for 18 hours at 4C. After cooling, 6 cores, 1.27 cm in diameter were removed parallel to the longi tudinal orientation of the muscle fibers.

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55 Cores were sheared once perpendicular to the longitudinal orientation of the muscle fibers with a Warner-Bratzler shear head at a cross-head speed of 200 mm/min, attached to an Instron Universal Testing machin e (Instron Corporation, Canton, MA). Sensory Attributes Steaks designated for sensory panel evaluati on (SP) were treated and cooked to the same specifications as the WBS samples. Upon reaching 71C internal temperature, steaks were served to panelists while stil l warm. Sensory panelists evaluated 5 – 6 samples, 2 sample cubes 1.27 cm2 per sample, served in warmed covered containers twice daily in a positive pressure ventilation room with lighting and cubicles designed for objective meat sensory panels. A 7 – 11 me mber sensory panel trained according to AMSA sensory evaluation guidelines (AMSA, 1995) evaluated each sample for 4 sensory attributes. The four evaluated sensory tra its included overall tenderness (1 = extremely tough, 2 = very tough, 3 = moderately tough, 4 = slightly tough, 5 = slightly tender, 6 = moderately tender, 7 = very tender and 8 = ex tremely tender), beef flavor intensity (1 = extremely bland, 2 = very bland, 3 = moderately bland, 4 = slightly bland, 5 = slightly intense, 6 = moderately intense, 7 = very intense and 8 = extr emely intense), off-flavor (1 = extreme off-flavor, 2 = strong off-flavor, 3 = moderate off-fl avor, 4 = slight off-flavor, 5 = threshold off-flavor and 6 = no off-fla vor detected), and o ff-flavor descriptor (metallic, grassy, livery, grainy, gamey or othe r). Off-flavor descriptors will be shown and discussed in a subsequent chapter. Statistical Analysis The data for carcass characteristics were analyzed as a completely randomized design with carcass as the experimental unit to determine if carcass characteristic means differed among the 5 slaughter groups. Car cass was the experimental unit and carcass

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56 nested in group was considered a random variab le and was used as the error term to test the effects of sources of variation. The m odel utilized to test the variance followed: yij = + ai + eij where yij was the jth observation from the ith slaughter group, was the population carcass characteristic mean, ai was the slaughter group effects and eij was the random error effects of carcass within slaught er group. The analysis of Warner-Bratzler shear force and sensory attributes was conduc ted utilizing a split-plot design where carcass was considered the whole-plot and musc le was the sub-plot and the experimental unit. The core for WBS or the cube fo r sensory analysis was considered the observational unit. For split-plot analysis of WBS and sensory panel data, carcass nested within slaughter group was considered the rando m effect of the whole plot, and muscle x carcass nested within slaughter group was cons idered the random term for the sub-plot of muscle. The model utilized followed yijk = + gi + bij + mk + (gm)ik + eijk, where yijk was the WBS or sensory attribute value for muscle k in animal j for slaughter group i, was the population mean for WBS or sensory attribute, gi was the effect of the ith slaughter group, bij was the random error effect of carcass j in slaughter group i, mk was the effect of the kth muscle, (gm)ik was the interaction effect betw een slaughter group i and muscle k, and eijk was the sub-plot random error of the kt h muscle of the jth carcass in the ith slaughter group. The Mixed procedures of St atistical Analysis System V. 9.1 (2002, SAS Inst. Inc., Cary, NC) were used to test the completely randomized and split-plot models. Means were separated using the PDIFF op tion in LSMEANS due to missing values. Differences among means were considered si gnificant at an al pha level 0.05.

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57 Results and Discussion Carcass Characteristics Carcass characteristics and carcass compositi on are summarized in Tables 3-1 and 3-2, respectively. Cull cow carcasses designate d as B-NF had the lightest HCW while BF and D-NF were similar (P > 0.05) to th e SEL group. The D-F group had the heaviest (P < 0.05) HCW. As well, D-F had highest predicted percent bone and more weight in bone and predicted carcass fat free lean (CFFL) than the other 4 groups (Table 3-2). The SEL group had the largest REA but was similar (P > 0.05) to B-F followed by D-F, B-NF and finally D-NF. B-F carcasses had the mo st (P < 0.05) FOE which corresponded with the lowest PL, highest percent fat and more pr edicted carcass weight in fat than any other group which contributed to the largest (P < 0.05) PYG. SEL carcasses were intermediate in FOE while B-NF, D-NF and D-F exhibited the least FOE. Preliminary yield grade followed FOE measurements with B-NF, D-NF and D-F all being similar and lower than B-F or SEL groups. SEL carcasses had the hi ghest muscling score which was expected. However, the B-F group had more (P < 0.05) muscling than the B-NF group, while D-NF and D-F were similar (P > 0.05) in muscling. Feeding cull cows either a high energy (above maintenance) or low energy (at maintenance) diet, Miller et al. (1987) repor ted similar findings to those found in the current research. Cull beef cows fed a highe r energy diet had heavie r hot carcass weights and larger ribeye areas than the cows fed a lo w energy diet. As well, Miller et al. (1987) reported similar 12th rib fat thickness (15.5 mm) and yield grades (3.4) as reported in the current research. Brown and Johns on (1990) reported increases in 12th rib fat thickness, ribeye area and hot carcass wei ghts when cull cows were supplemented with ammoniated

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58 hay, citrus pulp, cane molasses or cane mo lasses with cotton seed meal. However, differences were not obser ved for yield grade between the treatments. When quality grade factors were consider ed, the SEL group had the most desirable carcasses. Since the other four groups were representations of cull cow populations, their maturities were great enough that they were only eligible for Commercial or lower quality grades. B-NF numerically had the ol dest maturity scores for both bone and lean maturity. D-NF and D-F were younger but similar (P > 0.05) to B-NF in both bone and lean maturities. However, the B-F group wa s significantly (P < 0.05) younger than the B-NF group in bone and lean maturity. It has been widely reported that feeding a high energy prior to slaughter can improve lean maturity scores. Cranwell et al. (1996a) reported that lean maturity scores decreased in cull beef cows as time on feed increased from 0 to 56 days on feed. Faulkner et al. (1989) noticed improvements in lean maturity when cull cows were fed a concentrate diet for 42 days but did not see any further improvements. As well, within type of ca ttle, carcass marbling scores increased for the groups that were perceived to have been fed a higher plane of nutrition. B-NF and D-NF groups were eligible for USDA Utility quali ty grade standards while both B-F and D-F were eligible for USDA Commercial quality grade. Although D-F had older maturity scores than B-F, D-F also had significantly higher (P < 0.05) marbling scores, while the lower lean maturity of the B-F group help it to maintain a more desirable quality grade. SEL carcasses had the brightest lean afte r blooming and the whitest fat of all groups examined. Cull dairy cows commercially identified as bei ng fed a high energy prior to slaughter were similar (P > 0.05) in lean color, bu t had whiter (P < 0.05) fat when compared to commercially identified non-fed cull dairy cows. Commercially identified

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59 as fed cull beef cows had carcasses that were br ighter in their lean (P < 0.05) and whiter in their fat (P < 0.05) than commercially identified non-fed cull beef cows. B-NF was similar (P > 0.05) to D-NF and D-F in lean co lor, but B-NF had the yellowest fat color (P < 0.05) of all five groups researched. The ye llow fat reported in the B-NF group could be attributed to increased carote ne content that is deposited in the lipid tissues of animals when fed a forge based diet that is high in carotene (Yang et al., 1992). Grains tend to have lower concentrations of carotenoids than forages (Stranchan et al., 1993). Therefore, if the cull cows of the present st udy were fed high energy diets with grains in them, the lightening of fat could have been caused by a dilution effect of more fat being deposited with less carotene (French et al., 2000). Feeding high energy diets to cull cows prior to slaughter has the ability to increase the quality grade by two primary factors: Lean maturity scores tend to decrease and marbling scores tend to increase. Lean maturity scores are improved by producing a brighter lean (Miller et al., 1987; Bolema n et al., 1996; Cranwell et al., 1996a) and firmer, finer textured lean (Brown and Johnson, 1990). The second factor affecting quality grades in cull cows is an increased marbling score associated with feeding a high energy diet prior to slaughter (Matulis et al., 1987; Miller et al., 1987; Cranwell et al., 1996a). However, Sawyer et al., (2004) repor ted no differences in cull cow lean color, fat color, marbling score, lean maturity and overall maturity when cows were fed conservatively (30% roughage, 70% concentrate) or aggres sively (decreasing roughage from 30% to 10%, and concentrate). SEL carcasses had similar (P > 0.05) predicted percent CFFL when compared to BNF carcasses and similar (P > 0.05) percen t carcass fat to B-NF and D-NF groups.

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60 However, D-F carcasses numerically had the most predicted CFFL weight of any group but the least (P < 0.05) percent C FFL. As stated previously, th is is attributed to heavier HCW recorded for the D-F group. D-F carcasse s had the lowest (P < 0.05) predicted percent CFFL and B-F carcasses had the sec ond lowest percent CFFL. However, B-F carcasses had the highest (P < 0.05) predicted percent fat, followed by D-F carcasses. Dairy type cull cow carcasses had the most predicted bone as a percent of the carcass followed by B-NF. B-F and SEL carcasses were similar (P > 0.05) in percent bone. B-F and SEL groups were similar (P > 0.05) in CFFL weight, but the B-F group had significantly more (P < 0.05) car cass weight in fat than B-NF , D-NF or SEL groups. As expected, dairy type cull cows had more pr edicted carcass weight in bone than B-NF, B-F and SEL which were all similar (P > 0.05) in carcass bone weight. Brown and Johnson (1990) found that when cull cows were fed ammoniated hay with citrus pulp or cane molasses, per cent carcass fat free lean and percent bone decreased while percent carcass fat increased wh en compared to cull cows fed only hay. It was also reported in the previous study th at when cottonseed meal was added to the supplemented diets, percent bone still decreased and percent fat still increased. However, percent carcass lean did not differ between treat ments. Similarly, Faul kner et al. (1989) and Cranwell et al. (1996b) reported that in realimented cull cows, perc ent carcass bone decreased with increasing time on concentrat e feed and carcass soft tissue increased. However, soft tissues were not separated into lean and fat. Therefore, the increase in percent soft tissue may have been due to an in crease in carcass fat as it was noted that 12th rib fat thickness and yield grades also incr eased with time on feed. Matulis et al. (1987) found that carcass fat free lean and fa t weight both increased significantly the

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61 longer cull cows were on a concentrate diet pr ior to slaughter. The carcass fat free lean gained at a similar rate for all feeding pe riods (0, 28, 56 and 84 days on feed), while fat weight gained the most at 28 days on feed and then increased at a lower rate for each feeding period thereafter. Warner-Bratzler Shear Force The interaction of group x muscle for WBS (P < 0.05) is shown in Table 3-3 (Figures 3-1, 3-2, and 3-3). The LOD fo r B-NF had the highest WBS value and was therefore the least tender muscle examined fo r all muscle x group interactions. Within the B-NF group, LOD was the least tender muscle but was similar (P > 0.05) to GLM and LON. This was followed by TEM, REF, LAT and TFL. The PSO was the most tender muscle (requiring less force to shear) and was similar (P > 0.05) to the INF. For the B-F group, the GLM was the least tender muscle ex amined followed by the LON, REF, LOD, TEM and LAT. The INF and PSO were the mo st tender muscles identified in the B-F group and were similar (P > 0.05) to each othe r. The TFL was the third most tender muscle found in the B-F group. Likewise, fo r the D-NF group, GLM was the least tender muscle but was similar (P > 0.05) in WBS values to the REF, LON, LOD, TEM and LAT. Similar to the B-F group, the INF was numerically the most tender muscle within the D-NF group but was similar (P > 0.05) to PSO and TFL. For the D-F group, the LOD was the least tender muscle and was similar (P > 0.05) to the LON, GLM, REF, TEM and LAT. The PSO was the most tender muscle found for the D-F group but was similar (P > 0.05) to the INF and TFL. For the SEL gr oup, the LOD was the least tender muscle found followed by the GLM, TEM, REF, LON and LAT. Again, among the SEL carcasses the INF was the most tender muscle with the PSO and TFL being second and third in WBS ranking, respectively.

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62 Dryden et al. (1979) reported WBS va lues for 8 muscles from cull cows realimented for 0, 38, 63 and 108 days. An effe ct from feeding was only realized on two of the 8 muscles studied: the m. Semimembranosus decreased in WBS value after 108 days on feed while the m. Rectus femoris increased in WBS value at 108 days on feed. Contrary to the current study, Crouse et al. (1984) reported that dietary treatment of either grass or concentrate in steers did not affect WBS values of three muscles studied (2 from the round and 1 from the loin). It was also reported in this study that no significant interaction existed between dietary treatment and muscle. Examining muscles of the chuck (Figure 3-1) it was noticed that INF had the lowest WBS value irrespectiv e of group. For each muscle (INF, LAT, LON and TEM) WBS values were lower for steaks from the B-F group than from the B-NF group. This difference was significant (P < 0.05) for th e INF and TEM. The INF, LAT, LON and TEM were similar (P > 0.05) for B-F, D-NF and D-F groups. However, the SEL group had significantly lower (P < 0.05) WBS va lues for the INF, LAT and LON when compared to the other 4 groups. The muscles fr om the chuck for cull beef cows that were affected the most by supplemental feeding prio r to slaughter were the INF and the TEM. The muscles of the loin (LOD and PSO) are shown in Figure 3-2. The PSO was not significantly different (P > 0.05) for a ny group. However, the LOD had significantly higher (P < 0.05) WBS values for the B-NF group when compared to B-F, D-NF, D-F and SEL groups which were similar (P > 0.05) to each other. The LOD was almost 2 kg lower in WBS value between B-NF and BF groups which was the largest difference noted for a muscle between groups observed during this study. Mo st of the current literature examining cattle fed diets of differing energy levels focuses on the m.

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63 Longissimus dorsi . Boleman et al. (1996) reported that longissimus WBS values significantly decreased after cull cows were on a concentrate diet for 56 days, while Faulkner et al. (1989) reported a decrease in cull cow loin shear force after 42 days on feed. Cranwell et al. (1996a) al so reported a decrease in loin shear force after 28 days on concentrate but did not observe any further d ecreases. In opposition to the current study, Brown and Johnson (1990) did not report a significant difference for longissimus WBS values when cull cows were fed hay or high energy supplements prior to slaughter. The muscles of the sirloin (GLM) and r ound (REF and TFL) are shown in Figure 33. The GLM had the highest WBS value fo r the B-NF group, and then was lower and similar (P > 0.05) for the B-F, D-NF and D-F groups. The GLM WBS values were the lowest for the SEL group and were similar (P > 0.05) only to the D-F group. The REF WBS values were similar (P > 0.05) for the B-NF, B-F, D-NF and D-F groups but were significantly lower (P > 0.05) for the SEL gr oup. However, the REF WBS scores were numerically lower for the B-F and D-F gr oups than for the B-NF and D-NF groups, respectively. The TFL was similar (P > 0.05) in WBS scores for the B-NF, B-F, D-NF and D-F groups. The TFL from the SEL gr oup was significantly lo wer (P < 0.05) than the B-NF and B-F groups. B-NF group was the least tender group (P < 0.05) when all muscles were averaged for their WBS values (Table 3-4). There was no difference (P > 0.05) between the B-F, D-NF and D-F groups. The SEL group was sign ificantly (P < 0.05) more tender than any of the other groups studied when comparing WBS values. It has been well documented that heat liable collagen content decreases with advancing age (Hil l, 1966; Herring et al., 1967; Bailey and Shimokamaki, 1971), which would explain the differences noticed

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64 between SEL and the other four groups. Aber le et al. (1981) conc luded feeding cattle high energy diets would promote rapid rates of protein synthe sis and produce beef with a high proportion of newly synthesized, heat li able collagen. Therefore, B-F and D-F groups may have been more tender than the B-NF group due to increases in heat liable collagen that was gained during lean accreti on, as evidenced by the increase in REA. The main effect of muscle on WBS value (Table 3-5) shows th at the GLM was the least tender muscle examined but was simila r (P > 0.05) to the LOD and LON. The PSO had the lowest WBS value, making it the most tender muscle studied. However, the PSO was similar (P > 0.05) to the INF. The TF L was significantly diffe rent (P < 0.05) from the PSO and INF but, it was the third most tender muscle found. Based on WBS values, LAT, LON, REF and TEM showed promise as muscles that could be fabricated into steaks with intermediate tenderness and the IN F and TFL could be fabricated into steaks with a high tenderness rating. Sensory Attributes The main effect means of group and muscle on sensory panel attributes are shown in Table 3-4 for carcass group, a nd Table 3-5 for muscle. Ther e was not a significant (P > 0.05) group x muscle interaction for the se nsory attributes of overall tenderness and beef flavor intensity. However, there was a significant group x mu scle interaction for sensory off-flavor detection which will be discussed in a subsequent chapter. The group main effect means for sensory overall tenderness followed the same trend as did carcass group main effect m eans for WBS values. The SEL carcass group was rated as being significantly more tende r (P < 0.05) than B-NF, B-F, D-NF and D-F carcass groups. In agreement with the WBS results, B-NF was rated as being the least tender (P < 0.05) group while B-F, D-NF and D-F were similar (P > 0.05) for sensory

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65 overall tenderness. Boleman et al. (1996) a nd Cranwell et al. (1996a) both reported that realimented cull cows were rated as being more tender than cull cows that were not realimented. Boleman et al. (1996) conc luded that as time on a high energy diet increased, myofibrillar fragmentation becam e easier and detectable connective tissue decreased, therefore contributing to the impr ovement in overall tenderness. Conversely, several authors reported that feeding high energy diets vers es low energy diets to young steers had no significant effect on sensor y overall tenderness (Bidner et al., 1985; Schaake et al., 1993). Similarly, Miller et al. (1987) reported no difference in loin sensory tenderness between cull cows fed either a high energy diet or a maintenance diet prior to slaughter. Dryden et al. (1979) reported no diffe rence between fed and non-fed cull cows for the m. Semimembranosus and m. Triceps brachii . However, the m. Gluteus medius and m. Biceps femoris both increased in sensory te nderness when cull cows were realimented. There was no difference (P > 0.05) betw een cull cow groups for beef flavor intensity. However, the SEL group was significa ntly (P < 0.05) lowe r in beef intensity flavor than the other four groups, with a di fference of only 0.2 units on a scale that rated beef intensity flavor from 1 – 8. The B-NF group had the most (P < 0.05) off-flavors detected, while the SEL group had the least am ount (P < 0.05) of off-flavors detected. The B-F, D-NF and D-F groups were similar (P > 0.05) in their scores for sensory offflavor detection. Boleman et al. (1996) f ound that feeding cull cows a concentrate diet prior to slaughter increased beef intensity flavor by 56 days on feed and decreased offflavor detection by 28 days on feed. However, Faulkner et al. (1989) reported an increase in beef flavor intensity for cull cows that were fed a concentrate diet for 42 days, but

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66 found off-flavor was not affected as time on feed increased. Cranwe ll et al. (1996a) also reported an increase in beef in tensity flavor at 28 days on f eed, but no further increases in flavor intensity were seen as cull cows were fed longer. Muscle differences in sensory overall te nderness (Table 3-5) did not follow the trends found by the WBS values. Although PSO was identified as the most tender muscle, it was similar (P > 0.05) in overall tenderness to TEM. INF was the third most tender muscle as identified by sensory pane lists. The LON, REF, TFL, LAT and LOD were all similar (P > 0.05) a nd rated as slightly tender by sensory panelists. Similar to WBS values, the GLM was rated the least tender muscle with an overall rating of slightly tough. Little difference was noted among muscle s for sensory beef intensity flavor. All muscles were similar (P > 0.05) for beef fl avor intensity except the INF which was significantly lower (P < 0.05) th an all other muscles. Dryden et al. (1979) found no difference in fl avor intensity for the main effects of muscles or diet for cull cows that were realimented. The LAT was rated by sensory panelists as having the most o ff-flavor (slight off-flavor) a nd was similar (P > 0.05) to the PSO and GLM, both rated on the borderline of sl ight off-flavor and th reshold off-flavor. The REF, TFL and LON had the least off-fl avor while the LOD, INF and TEM were scored as having threshold levels of off-flavor by the sensory panelists. However, it must be taken into consideration that approximately half of the samples tested for the LAT, PSO and GLM were scored as having no offflavor, which masked the intensity of the samples with strong off-flavors when the data was pooled. Implications This research indicates that although cull cows commercially identified as being fed a high energy ration prior to slaughter are not similar to A-maturity USDA Select

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67 carcasses, they do show improvements over cull cows that are commercially identified as not fed. Carcasses from supplemented beef and dairy cows had more desirable carcass characteristics than did cull beef cows that were not supplemented prior to slaughter. There was not a large magnitude of differen ce between commercially identified non-fed dairy cows and commercially identified fed dairy or beef cull cow carcasses for shear force values or sensory attributes. The gr eater difference between beef types and dairy types could be attributed to dairy animals being on a higher plane of nutrition to support lactation. However, cull cows of the beef a nd dairy types that were identified as fed had increased carcass quality and pr oduced more weight in lean than cull cows identified as non-fed. As well, cull cows identified as fe d had a decreased inci dence of off-flavor detection and had several muscles si milar to or more tender than the m . Longissimus dorsi muscle. These muscles could be used in value added systems to fill a need for intermediately priced beef steaks that are still palatable to the consumer. More research is warranted to examin e the effects of diet on quality variables between different muscles of realimented cull cows. As well, research is needed to examine methods of increasing the proportion of lean to fat in realimented cull cows to maximize cutability and value of the carcass. Effects of diet on off-flavors of muscles from cull cow carcasses also warrants more research. In studies such as this one, threshold off-flavors could be an indicator of severe off-flavors being present in some samples. Off-flavor is sometimes masked when muscles in a group are pooled because not all samples exhibited off-flavors. This caused the severity of off-flavors in some samples to be negated by those that had no off-flavor.

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68 Table 3-1. Least squares means for carcass characteristics1 Group2 Trait B-NF B-F D-NF D-F SEL SEM HCW, kg 302.5c 377.4b 354.4b 406.5a 356.6b 10.25 REA, cm2 71.6cd 82.7ab 68.1d 79.3bc 91.2a 3.19 FOE, cm 0.68c 1.6a 0.58c 0.75c 1.03b 0.09 PYG 2.7c 3.6a 2.6c 2.7c 3.0b 0.09 Lean Maturity3 440a 374b 423ab 409ab 142c 18.05 Bone Maturity3 507a 437b 433b 472ab 145c 21.66 Lean Color4 3.5c 4.7b 3.6c 3.8c 6.3a 0.29 Fat Color5 4.5a 3.3c 4.0b 3.5c 2.1d 0.15 Marbling6 377cd 509b 450bc 608a 356d 30.72 Muscle Score7 520c 660b 430d 470cd 810a 19.52 1HCW = Hot carcass weight, REA = Ribeye area, FOE = Fat over the ribeye, PYG = Preliminary yield grade. 2B-NF = Beef Non-Fed, B-F = Beef Fed, DNF = Dairy Non-Fed, D-F = Dairy Fed, SEL = USDA Select. 3100 = A-maturity, 200 = B-maturity, 300 = C-maturity, 400 = D-maturity, 500 = Ematurity. 41 = extremely dark red, 2 = dark red, 3 = mode rately dark red, 4 = slightly dark cherry red, 5 = slightly bright cherry red, 6 = moderate ly bright cherry red, 7 = bright cherry red, 8 = extremely bright cherry red. 51 = white, 2 = creamy white, 3 = slightly ye llow, 4 = moderately yellow, 5 = yellow. 6100 = Practically devoid, 200 = Traces, 300 = Slight, 400 = Small, 500 = Modest, 600 = Moderate, 700 = Slightly abunda nt, 800 = Moderately abundant. 7100 = light-, 200 = lighto, 300 = light+, 400 = medium-, 500 = mediumo, 600 = medium+, 700 = heavy-, 800 = heavyo, 900 = heavy+. abcdLeast squares means in the same row having different superscripts are significant at P < 0.05.

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69 Table 3-2. Least squares means for carcass composition1 Group2 Trait B-NF B-F D-NF D-F SEL SEM CFFL3 % 64.1a 58.5bc 60.2b 57.1d 64.9a 1.01 Fat3 % 14.8c 24.0a 16.1c 20.6b 17.3c 0.97 Bone3 % 16.0b 12.1c 18.0a 16.5ab 12.8c 0.56 CFFL4, kg 199.3d 226.9bc 221.6c 245.0a 238.5ab 5.80 Fat4, kg 45.7c 95.2a 60.7b 89.0a 63.7b 4.81 Bone4, kg 49.8b 47.23b 66.9a 70.7a 46.9b 2.88 Lean % 81.7a 71.4c 80.4a 76.7b 77.2b 0.93 1CFFL = Carcass fat free lean. 2B-NF = Beef Non-Fed, B-F = Beef Fed, DNF = Dairy Non-Fed, D-F = Dairy Fed, SEL = USDA Select. 3Values calculated by the equati ons of Johnson and Rogers (1997). 4Values calculated by multiplying percent of carcass composition by HCW. abcdLeast squares means in the same row having di fferent superscripts are significant at P < 0.05.

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70 Table 3-3. Least squares means1 for Warner-Bratzler2shear force interaction of group by muscle Group3 Muscle4 B-NF B-F D-NF D-F SEL GLM 7.44a,tu 6.25b,t 6.30b,t 5.85bc,t 5.16c,t INF 4.88a,y 4.00b,v 3.77b,w 3.77b,v 2.96c,x LAT 5.71a,wx 5.65a,tu 5.34a,tuv 5.66a,t 4.42b,uv LOD 7.58a,t 5.68b,tu 5.82b,tu 5.99b,t 5.33b,t LON 6.81a,tuv 6.14ab,t 5.94b,tu 5.89b,t 4.65c,tuv PSO 3.93a,z 4.02a,v 3.94a,w 3.52a,v 3.62a,wx REF 6.24a,vw 5.76a,tu 6.03a,tu 5.79a,t 4.76b,tuv TEM 6.65a,v 5.66b,tu 5.81b,tu 5.71b,t 5.09b,tu TFL 5.30a,xy 5.20a,u 4.77ab,v 4.93ab,u 4.16b,vw 1Standard error of least squares means for all interactions = 0.28. 2Warner-Bratzler shear force measurements are in kg. 3B-NF = Beef Non-Fed, B-F = Beef Fed, DNF = Dairy Non-Fed, D-F = Dairy Fed, SEL = USDA Select. 4GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae . abcLeast squares means in the same row having di fferent superscripts are significant at P < 0.05. tuvwxyzLeast squares means in the same column having different superscripts are significant at P < 0.05.

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71 0 1 2 3 4 5 6 7 8 Beef Non-FedBeef FedDairy NonFed Dairy FedSelect GroupWarner-Bratzler Shear, kg INF LAT LON TEM Figure 3-1.Warner-Bratzler shear force least squares means for the interaction of muscle by gr oup for muscles of the chuck.

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72 0 1 2 3 4 5 6 7 8 9 Beef Non-FedBeef FedDairy NonFed Dairy FedSelect GroupWarner-Bratzler Shear, kg LOD PSO Figure 3-2. Warner-Bratzler shear force leas t squares means for the interaction of mu scle by group for muscles of the loin.

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73 0 1 2 3 4 5 6 7 8 9 Beef Non-FedBeef FedDairy NonFed DairyFedSelect GroupWarner-Bratzler Shear, kg GLM REF TFL Figure 3-3. Warner-Bratzler shear force least squares means for the interaction of musc le by group for muscles of the sirloin a nd round.

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74Table 3-4. Warner-Bratzler shear force and sensory attribute least squares m eans for the main effect of group Group1 Trait B-NF B-F D-NF D-F SEL SEM Warner-Bratzler shear, kg 6.06a 5.37b 5.30b 5.23b 4.46c 0.14 Overall tenderness2 4.4a 4.9b 4.8b 4.9b 5.6c 0.09 Beef flavor intensity3 5.7a 5.7a 5.7a 5.7a 5.5b 0.04 Off-flavor4 4.8a 5.2b 5.3b 5.2b 5.5c 0.06 1B-NF = Beef Non-Fed, B-F = Beef Fed, D-NF = Dairy Non-Fed, D-F = Dairy Fed, SEL = USDA Select. 21 = Extremely tough, 2 = Very tough, 3 = Mode rately tough, 4 = Slightly tough, 5 = Slightly tender, 6 = Moderately tender, 7 = Very tender, 8 = Extremely tender. 31 = Extremely bland, 2 = Very bland, 3 = Mode rately bland, 4 = Slightly bland, 5 = Sli ghtly intense, 6 = Moderately intense, 7 = Very intense, 8 = Extremely intense. 41 = Extreme off-flavor, 2 = Strong off-flavor , 3 = Moderate off-flavor, 4 = Slight o ff-flavor, 5 = Threshol d off-flavor, 6 = No offflavor. abcLeast squares means in the same row having di fferent superscripts ar e significant at P < 0.05.

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75Table 3-5. Warner-Bratzler shear force and sensory attribute least squares m eans for the main effect of muscle Muscle1 Trait GLM INF LAT LOD LON PSO REF TEM TFL SEM Warner-Bratzler shear, kg 6.20a 3.88f 5.36d 6.08ab 5.89abc 3.81f 5.72c 5.78bc 4.87e 0.12 Overall tenderness2 4.1d 5.1b 4.7c 4.7c 4.9c 5.6a 4.8c 5.5a 4.7c 0.08 Beef flavor intensity3 5.6a 5.4b 5.8a 5.7a 5.7a 5.7a 5.6a 5.7a 5.7a 0.05 Off-flavor4 5.1cd 5.2bc 4.9d 5.2bc 5.3ab 5.1cd 5.4a 5.2bc 5.3a 0.05 1GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae . 21 = Extremely tough, 2 = Very tough, 3 = Mode rately tough, 4 = Slightly tough, 5 = Slightly tender, 6 = Moderately tender, 7 = Very tender, 8 = Extremely tender. 31 = Extremely bland, 2 = Very bland, 3 = Mode rately bland, 4 = Slightly bland, 5 = Sli ghtly intense, 6 = Moderately intense, 7 = Very intense, 8 = Extremely intense. 41 = Extreme off-flavor, 2 = Strong off-flavor , 3 = Moderate off-flavor, 4 = Slight o ff-flavor, 5 = Threshol d off-flavor, 6 = No offflavor. abcdefLeast squares means in the same row having di fferent superscripts ar e significant at P < 0.05.

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76 CHAPTER 4 BENCHMARKING SENSORY OFF-FLAVOR SC ORE, OFF-FLAVOR DESCRIPTOR AND FATTY ACID PROFILES FOR MUSCLES FROM COMMERCIALLY AVAILABLE BEEF AND DAIRY CULL COW CARCASSES Introduction Approximately 5.1 million head of cull beef and dairy cows were harvested in 2004 making up almost 13% of the domestic beef supply in the United States (USDA, 2005). Most cull cow carcasses have a high percent lean and little external fat, making them destined for lean trimmings and gro und beef production. Although cull cows are primarily a by-product of an i ndustry dedicated to producing grain-fed A-maturity beef (Cranwell et al., 1996), they ar e still a valuable resource to producers accounting for 1520% of total revenues (Sawyer et al., 2004). Off-flavor production has prove n to be a detrimental quali ty factor in many cull cows, especially those of low quality and havi ng yellow external fat (Hilton et al., 1998). Beef (off-)flavor is strongly associated with the perception of meat pa latability and is an important consumer quality attribute. Suppl ementation or short-term feeding of cull cows prior to slaughter has been shown to improve both carcass ch aracteristics (Brown and Johnson, 1991; Cranwell et al., 1996a) and se nsory attributes (Boleman et al., 1996; Cranwell et al., 1996a) including off-flavor production (Bolem an et al., 1996). However, at the time of slaughter, the diet prior to slaughter is not always known and many cows are segregated based on body condition score and perception of either being fed a supplemental diet prior to slaughter or not. Carcasses from cull cows that were in good

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77 condition (6+) are separated from those of less condition (5 and lower) due to the potential increased value of their carcasses (Apple et al., 1999b). Feed source is the most important envir onmental factor influencing meat flavor (Shahidi et al., 1986), with hi gh energy diets producing red meat with a more acceptable flavor (Melton, 1990) and less off-flavor (H edrick et al., 1983; Larick et al., 1987; Bennett et al., 1995) than low-energy diets. Along with improving carcass and sensory characteristics, supplemental f eeding prior to slaught er has been shown to alter the fatty acid composition in beef (Elmore et al., 2004; Re alini et al., 2004; Ba ublits et al., 2006). It has been well documented that fatty acids contribute to the flavor of meats through lipid autooxidation (Macleod, 1998) and ther mal oxidation of especially long-chain polyunsaturated fatty acids (Farmer, 1994). Moreover, the thermal oxidation of longchain fatty acids can contribute to undesirable flavors (Mottram, 1987). Knowing the precursory factors contri buting to off-flavor in culls cows commercially identified as fed or not-fed coul d aid in further processing decisions. Much work has been conducted in the field of fla vor production in beef, however, to date no work has been done to establish benchmarks fo r off-flavors and fatty acid profiles in beef from cull cows commercially identified as fed or not-fed. Therefore, it was the objective of this research to benchmark sensory o ff-flavor production and fatty acid profiles in commercially identified fed and not-fed cull cow beef, and to determine if fatty acid composition was related to sensory off-fla vor production. It was hypothesized that cull cows commercially identified as fed will have less incidence of off-flavors, and have improved sensory off-flavor scores as a re sult of compositional changes in fatty acid profiles.

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78 Materials and Methods Carcass Selection Seventy-five carcasses were randomly sele cted from 5 groups of slaughter cattle commercially identified by trained plant personn el as beef non-fed (B-NF), beef fed (BF), dairy non-fed (D-NF), dairy fed (D-F) a nd concentrate fed A-maturity USDA Select (SEL) steers (n = 15 each group) from P ackerland Pack (Greenbay, WI). Cows commercially identified as non-fed are cows th at were perceived to be fed maintenance diets without supplemental ener gy. Cows commercially identif ied as fed are those that are perceived to be fed supplemental energy pr ior to slaughter base d upon live condition. Upon carcass selection, carcasses we re ribbed between the 12 – 13th rib junction and allowed to bloom for approximately 30 mi nutes. After blooming, carcass data was collected including: hot carcass weig ht (HCW), ribeye area (REA), 12th rib fat thickness over the ribeye (FOE), prelim inary yield grade (PYG), lean maturity (LM), bone maturity (BM), subjective lean color (LC), subjective fat color (FC), marbling score (MARB) and muscle score (MUS). Percent lean (PL) wa s calculated from carcass characteristics for all groups and carcass composition was calcula ted by the ribbed carcass equations of Johnson and Rogers (1997). Carcass data was presented in Chapter 3. After a 24 hour chill, designated carcasses were separated into primal cuts by trained plant personnel. Muscle s of interest were then excised from the chuck, loin and round. Muscles excised included m. Infraspinatus (INF), m. Triceps brachii – lateral head (LAT), m. Triceps brachii – long head (LON) and m. Teres major (TEM) from the chuck; m. Longissimus dorsi (LOD) and m. Psoas major (PSO) from the loin; and m. Gluteus medius (GLM), m. Rectus femoris (REF) and m. Tensor fasciae latae (TFL) from the sirloin and round. Muscles were vacuum pa ckaged and shipped to the University of

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79 Florida Meats Processing Center (Gainesville, FL). At the University of Florida Meats Processing Center, steaks were cut to 2.54 cm thickness across the grain from the posterior end of the muscle before being vacu um packaged and stored at 2C then frozen at -40C on day 14 postmortem. Sensory Off-flavor For a full description of sensory analysis refer to chapter 5 materials and methods – sensory attributes. The muscles utili zed in sensory testing included the m. Infraspinatus (INF), m. Triceps brachii – lateral head (LAT), m. Triceps brachii – long head, m. Teres major (TEM), m. Longissimus dorsi (LOD), m. Psoas major (PSO), m. Gluteus major (GLM), m. Rectus femoris (REF), and m. Tensor fasciae latae (TFL). Two steaks were cut 2.54 cm thick perpendi cular to the muscle fibers from the posterior end of the muscle after the removal of steaks fo r Warner-Bratzler shear force (WBS) testing (Chapter 3). Panelists were asked to scor e each sample presented to them for off-flavor (1 = Extreme off-flavor, 2 = strong off-flavor, 3 = m oderate off-flavor, 4 = slight off-flavor, 5 = threshold off-flavor and 6 = No off-flavor detected). Along with objectively scoring off-flavor, if an off-flavor was noticed the panelists were asked to describe or characterize the off-flavor to the best of thei r ability. The panelists were given a choice lexicon with metallic, grass y, livery, grainy, gamey, or other. The term gamey was used to characterize off-flavors that represented fl avors associated with cowy, old and serumy. If panelists characterized the off-flavor as “o ther” they were asked to describe the flavor in one or two terms. Fatty Acid Extraction One steak 2.54 cm thick was cut from the posterior end of the m. Longissimus dorsi perpendicular to the muscle fibers after steaks were cut for sensory evaluation and

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80 Warner-Bratzler shear force determination fo r fatty acid analysis. Steaks were vacuum packaged using a Multivac C500 packaging sy stem (Multivac Inc., Kansas City, MO) with Cryovac heat shrink vacuum bags (S ealed Air Corporation, Saddle Brook, NJ) and stored at -40C until further analysis. Fatty acids were extracted from muscle tissues in triplicate following a modified method of Sa sser (2001; MIDI Inc., Newark, Delaware). Briefly, four reagents were needed for sa ponification, methylation, extraction and sample cleaning. Reagent 1 (saponification) was made by addition of 45 g sodium hydroxide with 150 ml of methanol and 150 ml of distilled water. Reagent 2 (methylation) was made by the addition of 325 ml 6.0 N hydrochlor ic acid with 275 ml methyl alcohol. Reagent 3 (extraction) was made by mixing 200 ml hexane with 200 ml methyl tert-butyl ether. The final and fourth reagent (s ample cleanup) was made by dissolving 10.8 g sodium hydroxide in 900 ml of distilled water. Prior to fatty acid extraction the frozen st eak designated for fatty acid analysis was cut into cubes approximately 1.0 cm2, frozen in liquid nitrogen and powdered using a 700S Waring blender (Waring Laborator y, Torrington, Connecticut). During saponification 1.0 g of the pow dered meat was placed into a 13x100 mm culture tube (Sigma-Aldrich, St. Louis, Missouri), in dupl icate and 3.0 ml of reagent 1 was added. The tubes were tightly secured with Teflon lin ed caps, vortexed briefly and heated in a boiling water bath for 5 minutes. Capped tubes were then removed vortexed for 10 seconds and returned to the boiling water bath for 25 minutes. During methylation (formation of fatty acid methyl esters, FAME), the sample tubes were allowed to cool and 5.0 ml of reagent 2 was added. The tubes were recapped, vortexed and placed in a heated water bath at 80C 1C for 10 minutes. Extraction was conducted by addition of 1.25

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81 ml of reagent 3 and tumbling of the tubes in a clinical rotator for 10 minutes. The sample tubes were then uncapped and the lower aqueous phase was pipetted out and discarded. Finally, 3.0 ml of reagent 4 was added to the remaining organic phase and the tubes were tumbled again for 5 minutes. After tumbli ng, 1.0 ml of saturated sodium chloride was dispensed into the tube and allowed to sett le. Approximately 2/3 of the organic phase was pipetted into 2.0 ml vials capped with PTFE/Silicone septa (Sigma-Aldrich, St. Louis, Missouri) and placed in the gas chromatograph machine. Gas Chromatograph and Fatty Acid Methyl Ester Analysis FAME was analyzed by split injecti on into an Agilent 6850 gas chromatograph (GC) with a 25 m x 0.2 mm phenyl methyl silicone fused silica capillary column (Agilent Technologies, Palo Alto, California). The carri er gas used was hydrogen with air used to support the flame on the flame ionization detector. The temperature program utilized a ramp of 170C to 270C at 5C per minute. Between samples there was a ballistic increase to 300C with a hold of 2 minutes to allow for cleaning of the column. Peaks were identified by comparison to stored lib raries using Sherlock MIS software and Sherlock pattern recognition software (MIDI Inc., Newark, Delaware) which is detected automatically from an electronic signal pa ssed from the GC detect or to a computer containing the library software. Statistical Analysis The data for sensory panel off-flavor we re analyzed as a split-plot design as outlined in chapter 3. Carcass was consider ed the whole-plot factor and muscle was considered the sub-plot factor and experiment al unit. The cube served to the sensory panelist for each steak was considered the observational unit. Carcass nested within slaughter group was considered the random effe ct of the whole-plot, and muscle x carcass

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82 nested within slaughter group wa s considered the random term fo r the sub-plot of muscle. The model utilized followed yijk = + gi + bij + mk + (gm)ik + eijk, where yijk was the sensory off-flavor value for muscle k in animal j for slaughter group i, was the population mean for sensory off-flavor score, gi was the effect of the ith slaughter group, bij was the random error effect of carcass j in slaughter group i, mk was the effect of the kth muscle, (gm)ik was the interaction effect between slaughter group i and muscle k, and eijk was the sub-plot random error of the kth mu scle of the jth carcass in the ith slaughter group. The data for fatty acid composition wa s analyzed as a completely randomized design with carcass as the experimental unit and a steak from the LOD as the observational unit. Carcass nested within group was considered a random variable and was used as the error term to test the effect of sources of variation. The model utilized to test the variance followed: yij = + ai + eij where yij was the jth observation from the ith slaughter group, was the population mean fo r percent fatty acid in total lipid, ai was the slaughter group effects and eij was the random error effects of carcass with in slaughter group. The Mixed procedures of Statistical Analysis System V. 9.1 (2002, SAS Inst. Inc., Cary, NC) were used to test the sp lit-plot and completely randomized models. Means were separated using the PDIFF op tion in LSMEANS due to missing values. Differences among means were considered sign ificant at alpha leve l 0.05. Chi-square, Frequency procedures of Statistical Analys is System V. 9.1 (2002, SAS Inst. Inc., Cary, NC) were used to test the frequency distribut ion of off-flavor descriptors for the main effects of group and muscle. Frequency differe nces were considered significant at alpha level 0.05 for the Pearson chi-square statistic.

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83 To aid in the determination of a relationship between fatty acids and off-flavor production, principal components analysis (PCA) was performed via Princomp procedures of Statistical Analysis System V. 9.1 (2002, SAS Inst. Inc., Cary, NC). Sensory off-flavor data were separated and only LOD off-flavor scor es were used in conjunction with the fatty acid profile data obtained from the LOD. Principal components were retained for further examina tion when Eigen vectors were greater than one. The Reg procedures of Statistical An alysis System V. 9.1 (2002, SAS Inst. Inc., Cary, NC) were then utilized with off-flavor as the dependant variable and either the principal component loading or fatty acids as the independent variables. As well, the Reg procedures of Statistical Analysis System V. 9.1 (2002, SAS Inst. Inc., Cary, NC) was used to test summary and ratio variables as independent variables and off-flavor as the dependant variable. Effects of fatty acids on sensory off-flavor were considered significant at alpha level 0.05. Results and Discussion Sensory Off-flavor Exploring the sensory off-fla vor detection interaction of group x muscle (Table 4-1; Figure 4-1, Figure 4-2 and Figure 4-3) the S EL group had the least amount of detectable off-flavors, with an average score of 5.5 on a scale where 6 represents no off-flavors detected. There was not a significant differe nce (P > 0.05) between any of the muscles in the SEL group for sensory off-flavor score. The muscles with the most off-flavor detection in the B-NF group were the LAT and PSO, which had a higher incidence (P < 0.05) of off-flavors than any ot her muscle in the B-NF group. Little differences existed between any of the other muscles in the B-NF group except the LON which was numerically lower (indicating more off-fla vor, P < 0.05) than the INF, LOD, REF and

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84 TFL. As a whole, the B-F group had less dete ctable off-flavor than did the B-NF group. For the B-F group LAT, PSO, GLM, INF, LOD and TEM were all similar (P > 0.05) in off-flavor detection with scores at threshold levels. The two dairy groups were similar (P > 0.05) in their off-flavor dete ction scores, which were also similar (P > 0.05) to the B-F group. In both D-NF and D-F the LAT and INF were the muscles with the most offflavor detection. However, the only muscle that differed between the two groups was the PSO, which had less (P < 0.05) detectable offflavor in the D-NF group than in the D-F group. Miller et al. (1987) re ported that when cull cows were fed a high energy diet (above maintenance) prior to slaughter that off-flavors were st ronger (P < 0.05) when compared to cull cows fed a maintenance diet prior to slaughter. However, Boleman et al. (1996) found that grain feeding cull cows prior to slaughter decreased the magnitude of off-flavors in loin steak s. Dryden et al. (1979) found no difference in sensory offflavor score for different muscles when cull cows were realimented prior to slaughter. Examining muscles across treatment (Table 4-1), the GLM had similar (P > 0.05) sensory off-flavor scores for all cull cow gr oups. However the two beef cull cow groups had more (P < 0.05) off-flavor detection th an the SEL group. The only difference that existed for the INF was between D-F and SEL groups in which the D-F group had more (P < 0.05) off-flavor than the SEL group. The LAT had more (P < 0.05) off-flavor in the B-F group than in the other four groups, but the B-F, D-NF and D-F groups were rated as having more (P < 0.05) off-flavors than the SEL group. The B-NF LOD was similar (P > 0.05) in off-flavor detection to the B-F group but had more (P < 0.05) off-flavor than the other three groups. The LON and the PSO in the B-NF group had more (P < 0.05) offflavor than the other four groups. For the REF the B-NF group numerically had the most

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85 off-flavor according to sensor y panel ratings, but was simila r (P > 0.05) to the D-NF and D-F REF off-flavor scores. The B-F and SEL groups had the highest sensory off-flavor ratings for REF, which were also similar to the D-NF and D-F groups. The TEM was similar in off-flavor scores (P > 0.05) betw een the two beef groups , but the TEM for the B-NF group had more (P < 0.05) off-flavor th an the two dairy groups and the SEL group. Likewise, off-flavor score for TFL was similar (P > 0.05) between the two non-fed cull cow groups which were both rated as having mo re off-flavor than the SEL group, but the B-NF group also had more (P < 0.05) off-fla vor than the B-F and D-F groups. LAT had the most off-flavor (Figure 4-1) of the c huck muscles studied in all groups although it was similar to other muscles for the D-NF, D-F, and SEL slaughter groups. The B-NF PSO had the most off-flavor (Figure 4-2) of any muscle of the loin in any of the five slaughter groups, with little other differen ce being significant. REF had the least numerical (Figure 4-3) amount of off-flavor in all slaught er groups for muscles studied from the sirloin and round, while the GLM nume rically exhibited the most off-flavors. Examining the variation in palatabil ity, Rhee et al. (2004) found that the longissimus muscle had less off-flavor than muscles of the round in young carcasses. However, in the current study there were several muscles from all commercially identified slaughter groups that had less detectable sensory off-flavor than the m. Longissimus dorsi . Off-flavor descriptor fre quency by group is presented in Table 4-2 and Figure 4-4. Differences were significant among groups for different frequencies off-flavor descriptors (P < 0.05). The B-NF group had th e most sensory off-fl avor which lead the highest incidence of off-flavor descriptors followed by B-F, D-F, D-NF and SEL with the least amount of sensory off-flavor and off-flavor descriptors. The off-flavors of metallic

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86 and grainy were reported as havi ng the least incidence in all 5 groups. Fifty-nine percent of the samples in B-NF were reported to have off-flavors, of the 59% of samples recorded as having off-flavor grassy, gamey and “other ” accounted for the larg est percent (79%) of the off-flavor descriptors. The most common descriptor associated with “other” in the BNF group was fishy. Similarly, grassy, gamey a nd other were also th e most reported offflavors for B-F and D-NF accounting for 75.6% and 73% of off-flavors detected, respectively. The category of “other” in the B-F and D-NF group was commonly attributed to fishy or tallowy attributes. The off-flavors most commonly associated with D-F were livery, gamey or fishy (other) flav or sensations accounting for 70% of the offflavors described, when the characteristic flavor of grassy was included, these off-flavors accounted for 89% of all off-flavors record ed. The SEL group had the least amount of sensory off-flavor and therefore had the smalle st frequency of off-fl avor descriptors (31% of samples) associated with it. The most common off-flavors associated with the SEL group were gamey, fatty (other) and grass y, accounting for 74.4% of the noted offflavors. Although diets in the current study were not known, the frequency of off-flavor detection follows that of Lari ck et al. (1987) who found that as time on feed increased the frequency of detected grassy off-flavor decreased. Frequency of off-flavor de scriptors were also signi ficant (P < 0.05) among the different muscles (Table 4-4, Fi gure 4-5). Metallic and grainy descriptors had the lowest frequency of descriptors for all muscles. The most common off-flavors associated with the GLM, INF, LAT, LOD, REF, TEM and TFL were gamey, grassy and fishy (other) while the three most common off-flavors asso ciated with the PSO were fishy (other), gamey and livery. The three off-flavors most commonly associated with the LON were

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87 gamey, livery and grassy. The PSO had the hi ghest incidence of recorded off-flavors followed by GLM and LAT. REF had the smalle st incidence of reco rded off-flavor and was closely followed by TEM and TFL. Fatty Acid Composition Fatty acids as a percent of total extractable lipid and fatty acid ratio variables are presented in Table 4-4. The fatty acids C15: 0 and C16:0 were the only two fatty acids in the saturated class that diffe red among groups. The percentage of branched chain C15:0 was small as a percent of the total lipid, howev er, beef type carcasses contained a higher percentage (P < 0.05) of C15:0 than did dair y type carcasses. The percentage of total lipid that was palmitic acid (C16:0) was highe r (P < 0.05) in the D-F group than the other four groups which were all similar (P > 0.05). The percent of the total lipid that was saturated fatty acids (SFA) was not differe nt (P > 0.05) among the groups and ranged from 38 to 44%. The largest components of SFA were C16:0 and C18:0 which together composed between 30 and 35% of total lipid content and 75 -82% of saturated lipid composition. Total fatty acids made up of th e saturated class in the current study are slightly lower than those reported by Badian i et al. (2002) however, C18:0, and C16:0 were also reported as th e most common saturated fatty acids in their study. Monounsaturated fatty acid (MUFA) composition showed that C16:1 and C17:1 exhibited significant differences among groups, but that none of the other MUFA were different among slaughter groups. There were no discernable trends that distinguished one group from the other in the case of C16: 1, however, lipids from dairy type carcasses tended to have a higher percenta ge of total identifiable lipi d as C16:1 than did the beef types within commercial identification cla ss. The MUFA C17:1 exhibited a higher percent of the total lipid com ponent in beef type carcasses (P < 0.05) than in dairy type

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88 carcasses. Total identifiable MUFA constituted between 38 and 44% of the total lipid with C18:1 (oleic acid) making up the largest pa rt at percentages of 32 – 36% of the total identifiable lipid fraction. Total polyunsaturated fatty acids (PUFA) were considerably lower than SFA and MUFA as a percent of the to tal lipid. The PUFA C18:2 n-6 maintained the largest percentage of PUFA across all groups rangi ng from 2 to 5 percent of total lipid. Although differences were detected between gr oups for percent C18:2 n-6, a noticeable trend was not distinguished. A ll other PUFA were of small percentages (1% or lower). Differences did exist between cow types for C20:5 n-3 and C22:5 n-3 in which longissimus muscles from cull beef cow carcasse s exhibited an in creased (P < 0.05) percentage of these fatty acids as total lipid than did the dairy type groups or the SEL group. Arachidonic acid (C20:4 n-6) diffe red among groups, but again no trend was evident for animal type or commercial identif ication. The GC method used in the current study was not able to detect C18:3 n-3 (li nolenic acid) or C22:6 n-3 (docosahexaenoic acid) which are commonly found in ruminant tissues when the animal was fed forage or supplemented with certain feeds high in n-3 fatty acids such as fish oil (Mandell et al., 1997). However, Felton and Ke rley (2004) found that supple menting feedlot steers with different types and levels of fat did not have a large impact on the fatty acid composition of lipid from loin steaks. Selected ratios of MUFA/SFA and PU FA/SFA did not differ (P > 0.05) among commercially identified groups. The ratio of MUFA/SFA was close to a 1:1 ratio for all groups while the PUFA/SFA was very low ra nging from 0.09 to 0.16. The ratio results from the current study are in agreement with Ba diani et al. (2002) and Noci et al. (2005)

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89 and slightly lower than others (Cifuni et al., 2004; Baublits et al., 2006) for the longissimus muscle. A partial cause for the slightly lower PUFA/SFA ratio in the current study can be attributed to the high percenta ge of unknown or unaccounted for fatty acids in the current study. Some of the unaccounted for fatty acids that are in meat include C18:3 n-3 and C22:6 n-3. The SEL group numer ically had the highest PUFA/SFA ratio which was surprising, it was thought that commercially identified non-fed cull cows would have the increased PUFA/SFA ratios due to the fact they were most likely on higher forage diets prior to sl aughter. However, the increas ed PUFA/SFA ratio seen in the SEL group can be attributed to the num erically lower C16:0 and higher levels of C18:2 n-6 and C20:4 n-6 which are present in in creased values in animals that have been fed a grain based diet. Relationship of Fatty Acids and Sensory Off-flavor Principal components analysis (PCA) was utilized as a data reduction tool to investigate which fatty acids could have been associated with commercially identified groups having more off-flavor. Principal comp onents (PC) are presented in Table 4-5. Principal components 1-5 (PC 1PC 5) were re tained for further analysis as all of their Eigen values were greater than 1.0. The lin ear combinations of the first five PC accounted for 99% of the total variance among fatty acids. In PC 1, which accounted for the larges t portion of the total variance (73%) as shown by the Eigen values, only two fatty aci d groups were highly represented including C18:1 and the total percentage of unknown fa tty acids. Both of these were positively associated with PC 1 while there were no fatty acids with a strong negative association. In PC 1 it would be expected that C18:1 a nd unknown fatty acids were highly represented due to their large presence in the total lip id fraction for all groups. However, through

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90 regression analysis with off-fl avor as the dependant variable and PC 1 as the independent variable it was seen that the fatty acids hi ghly represented in PC 1 were not related to sensory off-flavor scores (P = 0.19, R2 = 0.02), therefore individual fatty acids were not analyzed from PC 1. The second principle component accounted for approximately 20% of the total variation (Eigen value of 22.26) in the fatty acid profiles which showed that C16:0, C18:0 and unknown were highly re presented, however, C18:1 was highly contrasted within PC 2. Again, when PC 2 was regressed with sensory off-flavor it was found that PC 2 was not highly related to off-flavor prediction (P = 0.55, R2 = 0.00). Principal component 3 only exhibited a strong positive representation from C18:0 and strong but milder contrasting results from fatty acids C14:1 and C16:1. As well, PC 4 had strong positive representation from C18:2 n-6 and a weaker but positive representation from the percenta ge of fatty acids that are unknown. Two fatty acids were negatively associated with PC 4, which were C16:0 and C18:1. However, through regression analysis it was found th at neither PC 3 nor PC 4 were related to off-flavor (P = 0.32, R2 = 0.01 and P = 0.52, R2 = 0.00, respectively). The fifth principal component only accounted for approximately 1% of the to tal variation found in the fatty acids. However, when regressed with sensory off-flavor PC 5 exhibited a slightly positive association (P = 0.01, R2 = 0.11). Examining the representa tive fatty acids in PC 5 it can be seen that C14:0, C18:0, C14:1 and C16:1 were positively represented, while C16:0, C18:1 and C18:2 n-6 were found to be cont rasting fatty acid vari ables. Beefy and tallowy were the second and third most comm only characterized off-flavors described by the term “other” in the flavor lexicon. Th ese two flavors have been associated with 2octenal and 2, 4-decadienal which are oxida tive breakdown products from C18:2 n-6

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91 (Reas et al., 2003). Upon further examination, of the individual fatty acids it was found that C14:0, C18:0, C16:1, C16:0, C18:1 and C18: 2 n-6 were not significantly related to off-flavor (P = 0.96, P = 0.65, P = 0.08, P = 0.25, P = 0.25 and P = 0.89, respectively). The only fatty acid out of PC 5 that was signifi cantly associated with sensory off-flavor was C14:1 (P = 0.02). Off-flavor score showed a slight increase (less off-flavor) as the percentage of C14:1 increased in the total lipid, however, with an R-square of 0.06 it would not make a good predictor of decreased off-flavor detection. Although PUFA were not highly represented in PCA analysis, it has been reported that PUFA may be responsible for off-fla vors in red meats due to the lipid oxidation process (Vatansever et al., 2000). Some of the compounds that result from PUFA oxidation include aldehydes, alcohols and ket ones (Larick et al., 1987; Larick and Turner, 1990a; Elmore et al., 1999). As well, Wood et al. (2003) concluded that if C18:3 n-3 levels account for approximately 3% of th e lipid fraction it may be detrimental to desirable flavor production. Linolenic acid (C18 :3 n-3) may be a fatty acid that is worthy of further exploration. The current study di d not test for C18:3 n-3, however, the most common off-flavor described in the B-NF gr oup was grassy. Forages typically have a high presence of C18:3 n-3 which could cont ribute to the grassy off-flavors commonly associated with pasture fed beef (Melton et al., 1982; Reas et al., 2003). Larick and Turner (1990b) have found that phospholipids ar e associated with off-flavor production, however, it was the phosphatidyl portion of the phospholipid th at was correlated the most to off-flavors such as sour and bloodlike. Grassy and gamey off-fl avors, which were the two most common off-flavors in the current study, were not affected by the phospholipid fraction of the lipids.

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92 When the principal components PC 1 and PC 5 were plotted against each other (Figure 4-6), because PC 5 showed a significan t relationship to sensor y off-flavor and PC 1 since it accounted for maximal variance, it can be seen that there is not any distinct separation of groups for the fatty acids that make up the total lip id fraction of the longissimus muscle indicating that fatty acids composition was fairly similar between groups. It has been hypothesized that fa tty acid ratio balance may be a greater determining factor in flavor production than individual fatty acids (Farmer, 1994). For this reason regression analysis was performe d looking at the ratios of MUFA/SFA and PUFA/SFA. It was found that in the current study fatty aci d ratios did not affect (P > 0.10, R2 < 0.06) sensory off-flavor score for longissimus steaks from the different slaughter groups. Implications Muscles from commercially identified non-fed cull beef cows tended to exhibit the most sensory off-flavor detection when comp ared to either commercially identified fed cull beef cows, dairy non-fed or fed dairy cull cows and Select A-maturity steers. Steaks from commercially identified fed cull beef cows, dairy non-fed and fed dairy cull cows were similar in sensory off-flavor ratings wh ile Select A-maturity steers exhibited the least amount of sensory off-flavor detection. Commercially identified fed cull beef cows and both groups of dairy type cull cows had less incidence of samples recorded as having off-flavors than did the commercially identifi ed beef non-fed group. Select steers had the smallest number of samples with off-flavors recorded out of any of the groups examined. Although fatty acids are known precursor s to off-flavor compounds, fatty acid composition was not an underlying factor in sensory off-fla vor scores in the current study. When examining factors that influe nce off-flavor production, it may be more

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93 beneficial to examine the total number of sa mples with a detectable off-flavor than sensory off-flavor score. More research is needed to determine the effect of a known diet on cull cow muscle flavor profiles, and to examine if a known diet will produce differences in fatty acid profile s that could impact off-fla vor production. However, it is apparent that commercially identifying fed cu ll cows may be beneficial in reducing offflavor in muscles that could be used for further processing.

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94 Table 4-1. Least squares means for sensory off-flavor1 interaction of group x muscle Group2 Muscle3 B-NF B-F D-NF D-F SEL GLM4 4.9b,wx 5.0b,z 5.2ab,wxy 5.2ab,wxy 5.4a,w INF5 5.1ab,w 5.2ab,wxyz 5.1ab,xy 5.0b,xy 5.4a,w LAT5 4.4c,z 4.9b,z 5.0b,y 5.0b,xy 5.4a,w LOD4 5.0b,w 5.2ab,wxyz 5.3a,wx 5.3a,wx 5.4a,w LON4 4.7b,xy 5.3a,wxy 5.5a,w 5.4a,w 5.5a,w PSO4 4.4d,z 5.1bc,xyz 5.3ab,wx 5.0c,y 5.6a,w REF5 5.1b,w 5.5a,w 5.3ab,wx 5.4ab,w 5.7a,w TEM5 4.8b,wx 5.2ab,wxyz 5.2a,wxy 5.2a,wxy 5.4a,w TFL4 5.0c,w 5.4ab,wx 5.2bc,wxy 5.4ab,w 5.6a,w 11 = Extreme off-flavor, 2 = Strong off-flavor , 3 = Moderate off-fl avor, 4 = Slight offflavor, 5 = Threshold off-fl avor, 6 = No off-flavor. 2B-NF = Beef Non-Fed, B-F = Beef Fed, DNF = Dairy Non-Fed, D-F = Dairy Fed, SEL = USDA Select. 3GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae . 4Standard error of l east squares means = 0.12. 5Standard error of l east squares means = 0.13. abcdLeast squares means in the same row having di fferent superscripts are significant at P < 0.05. wxyzLeast squares means in the same column ha ving different superscr ipts are significant at P < 0.05.

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95 0 1 2 3 4 5 6 Beef Non-FedBeef FedDairy NonFed Dairy FedSelect GroupSensory Off-Flavor INF LAT LON TEM Figure 4-1. Sensory panel off-flavor1 least squares means for the interaction of muscle by group for muscles of the chuck 11 = Extreme off-flavor, 2 = Strong off-fla vor, 3 = Moderate off-flavor, 4 = Slight o ff-flavor, 5 = Threshol d off-flavor, 6 = N o offflavor.

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96 0 1 2 3 4 5 6 Beef Non-FedBeef FedDairy NonFed Dairy FedSelect GroupSensory Off-Flavor LOD PSO Figure 4-2. Sensory panel off-flavor1 least squares means for the interaction of muscle by group for muscles of the loin 11 = Extreme off-flavor, 2 = Strong off-fla vor, 3 = Moderate off-flavor, 4 = Slight o ff-flavor, 5 = Threshol d off-flavor, 6 = N o offflavor.

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97 0 1 2 3 4 5 6 Beef Non-FedBeef FedDairy NonFed DairyFedSelect GroupSensory Off-Flavor GLM REF TFL Figure 4-3. Sensory panel off-flavor1 least squares means for the in teraction of muscle by group for muscles of the sirloin and round 11 = Extreme off-flavor, 2 = Strong off-flavor , 3 = Moderate off-flavor, 4 = Slight o ff-flavor, 5 = Threshol d off-flavor, 6 = No offflavor.

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98 Table 4-2. Chi-square1 frequency2 distribution for off-fl avor descriptors by group Group3 Descriptor B-NF B-F D-NF D-F SEL Metallic 30 18 12 24 19 Grassy 207 139 109 87 75 Livery 88 74 84 111 38 Grainy 15 29 30 29 29 Gamey 154 116 140 116 94 Other4 153 121 91 102 81 No off-flavor 452 602 633 630 763 % Off-flavor 59 45 42 43 31 1Chi-square is sign ificant at P < 0.0001 for group effects. 2There were 1099 total observations for each group. 3B-NF = Beef Non-Fed, B-F = Beef Fed, DNF = Dairy Non-Fed, D-F = Dairy Fed, SEL = USDA Select. 4Most common off-flavor for “Other” wa s fishy followed by fatty or tallowy.

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99 0 50 100 150 200 250 MetalicGrassyLiveryGrainyGameyOther Off-Flavor DescriptorFrequency Beef Non-Fed Beef Fed Dairy Non-Fed Dairy Fed Select Figure 4-4. Chi-square1 frequency2 distribution for offflavor descriptors3 by group 1Chi-square was significant at P < 0.0001 for group effects. 2There were 1099 observations for each group. 3Most common off-flavor for “Other” wa s fishy followed by fatty or tallowy.

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100Table 4-3. Chi-square1 frequency2 distribution of off-fla vor descriptors by muscle Muscle3 Descriptor GLM INF LAT LOD LON PSO REF TEM TFL Metallic 9 13 7 12 12 19 6 12 13 Grassy 72 65 80 64 63 67 76 76 54 Livery 45 36 55 26 68 69 27 38 31 Grainy 9 15 18 25 15 3 9 12 26 Gamey 102 86 79 73 66 70 44 44 56 Other4 64 63 60 79 39 85 42 47 69 No off-flavor 310 333 312 332 348 300 407 382 362 % Off-flavor 49 45 49 46 43 51 33 37 41 1Chi-square is signif icant at P < 0.0001 for muscle effects. 2There were 611 total observations for each muscle. 3GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae . 4Most common off-flavor for “Other” wa s fishy followed by fatty or tallowy.

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101 0 50 100 150 200 250 300 350 GLMINFLATLODLONPSOREFTEMTFL MuscleFrequency Metalic Grassy Livery Grainy Gamey Other Figure 4-5. Chi-square1 frequency2 distribution for offflavor descriptors3 by muscle4. 1Chi-square was significant at P < 0.0001 for muscle effects. 2There were 611 observations for each group. 3Most common off-flavor for “Other” wa s fishy followed by fatty or tallowy. 4GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae .

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102 Table 4-4. Fatty acid percentage of total lipid content of the m. Longissimus dorsi in commercially identified cull cows and Select A-maturity steers Group1 Fatty Acid B-NF B-F D-NF D-F SEL SEM C10:0 0.26 0.28 0.35 0.30 0.32 0.04 C12:0 0.13 0.21 0.22 0.21 0.22 0.04 C14:0 4.04 4.19 3.92 4.84 4.83 0.29 C15:0 0.53a 0.51a 0.28b 0.29b 0.51a 0.03 C16:0 25.15b 24.91b 25.38b 28.52a 23.39b 1.08 C17:0 0.53 0.75 0.30 0.40 0.41 0.13 C18:0 9.35 9.24 9.01 9.65 8.97 0.82 C14:1 1.13 1.53 1.57 2.04 1.39 0.25 C16:1 4.47b 5.01ab 5.37ab 6.06a 4.54b 0.38 C17:1 1.08a 1.19a 0.78b 0.64b 1.32a 0.09 C18:1 31.93 35.64 34.37 32.83 32.80 1.53 C18:4 n-3 0.05 0.09 0.00 0.02 0.00 0.02 C20:5 n-3 0.14a 0.17a 0.00b 0.00b 0.00b 0.03 C22:5 n-3 0.36a 0.19b 0.06c 0.03c 0.01c 0.04 C18:2 n-6 3.00bc 2.20c 3.89ab 4.05ab 4.96a 0.44 C20:3 n-6 0.26 0.20 0.27 0.25 0.25 0.04 C20:4 n-6 0.96ab 0.54bc 0.65abc 0.43c 1.02a 0.15 Unknown 20.87 28.67 26.91 30.09 23.59 2.58 SFA 39.99 40.08 39.45 44.20 38.65 1.97 MUFA 38.62 43.37 42.08 41.57 40.05 1.54 PUFA 4.77 3.39 4.87 4.78 6.24 0.62 MUFA/SFA 0.98 1.09 1.07 1.00 1.05 0.06 PUFA/SFA 0.13 0.09 0.12 0.11 0.16 0.02 1B-NF = Beef Non-Fed, B-F = Beef Fed, DNF = Dairy Non-Fed, D-F = Dairy Fed, SEL = USDA Select. abcLeast squares means in the same row having di fferent superscripts are significant at P < 0.05.

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103 Table 4-5. Principal components analysis (PCA ) for partitioning of fatty acid variance (percent of total lipid) for commercially identified fed and not-fed cull cows and Select A-maturity steers Principal Component Eigen Vectors Fatty acids PC 1 PC 2 PC 3 PC 4 PC 5 C10:0 -0.004 0.005 0.002 0.003 0.038 C12:0 -0.001 0.007 -0.004 0.011 0.048 C14:0 -0.029 0.110 -0.064 0.108 0.309 C15:0 -0.004 -0.001 0.020 0.000 0.026 C16:0 -0.019 0.745 0.068 -0.320 -0.519 C17:0 0.014 0.039 0.053 -0.038 -0.020 C18:0 -0.035 0.269 0.835 0.197 0.266 C14:1 0.002 0.035 -0.225 -0.013 0.296 C16:1 0.002 0.123 -0.425 -0.003 0.369 C17:1 -0.012 -0.032 -0.030 -0.002 0.058 C18:1 0.513 -0.486 0.182 -0.304 -0.308 C18:4 n-3 0.001 0.005 0.012 -0.018 0.000 C20:5 n-3 -0.001 -0.003 0.007 -0.028 0.015 C22:5 n-3 -0.004 -0.009 0.004 -0.040 -0.003 C18:2 n-6 -0.045 -0.050 -0.131 0.823 -0.453 C20:3 n-6 -0.004 -0.003 0.003 0.041 -0.020 C20:4 n-6 -0.020 -0.041 0.016 0.130 -0.055 Unknown 0.856 0.317 -0.085 0.235 0.168 Eigen values Eigen value 82.01 22.26 3.86 2.10 1.11 Prop. value 0.73 0.20 0.03 0.02 0.01 Cum. value 0.73 0.93 0.96 0.98 0.99

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104 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 -3-2-10123 Figure 4-6. Principal components pl ot for fatty acid analysis. PC 1 PC 5 + B-NF B-F D-NF D-F SEL

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105 CHAPTER 5 EFFECTS OF REALIMENTATION ON CULL COW PERFORMANCEAND POSTMORTEM AGING ON CARC ASS AND PALATABILITY CHARACTERISTICS OF SELECTED MUSCLES Introduction Many of the cull cows entering the market ar e sold at a body condition score of 4 or lower on a 9 point scale (NCBA, 1999). It has been shown that increasing body condition to a score of 6 prior to marketi ng may be advantageous to both producers and processors (Apple, 1999; Apple et al., 1999b). Carcass and quality defects in cull cows have also been outlined by several audits (NCA, 1994; NCBA 1999; Roeber et al. 2001) which included light muscling, low quality gr ade, light carcass weight and yellow carcass fat. These defects have been estimate d at $26.46 in unrealized value per cull cow (NCBA, 1999). Short-term realimentation of cu ll cows is a practical management tool for producers to consider in order to achieve a moderate body condition score and improve carcass and quality characteristics. At the same time, altering the marketing of cull cows from mid to late fall, when prices ar e historically the lowest, to late fall/early spring, when prices are historic ally at their highest, could improve producer profits. Increased feed energy levels prior to slaughter have been shown to increase sensory tenderness, decrease shear force values and increase soluble collagen content and percent soluble collagen in cull beef cows (Miller et al., 1987) as a result of increased protein synthesis (Aberle et al., 1981). Short-term supplementation after culling and prior to slaughter has also been shown to improve carcass and quality characteristics in cull cows including hot carcass weight, ribeye area, ma rbling, quality grade, and lean maturity

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106 scores (Brown and Johnson, 1991). Others have shown that cull cow short-term preslaughter concentrate feedi ng has increased protein yield (Matulis et al., 1987) soluble collagen content (Cranwell et al., 1996a), ri beye area, marbling and improve lean color scores (Boleman et al., 1996; Cranwell et al ., 1996a; Cranwell et al. 1996b). Concentrate feeding of cull cows has also been shown to decrease shear force values by 34, 14 and 30 %, and increase sensory tenderne ss ratings by 18, 39, and 7 % in the m. Longissimus dorsi by Faulkner et al. (1989), Boleman et al. (1996) and Cranwell et al. (1996a), respectively. Little research has focused on the effects of realimentation on the quality of muscles other than the m. Longissimus dorsi . However, Dryden et al. (1979) reported that realimentation reduced shear force for the m. Semimembranosus and m. Biceps femoris and increased sensory tenderness for the m. Gluteus medius and m. Biceps femoris . It is common practice for processors to remove the loin muscles from cull cow carcasses due to their increased value as a per cent of the carcass. If other muscles from the carcass of realimented cull cows are compar able to the muscles of the loin (especially the m. Longissimus dorsi ), carcass utilization may incr ease by making additional cuts from the carcass available for further processi ng. More research is warranted to examine the effects of realimentation on muscles other than the m. Longissimus dorsi in order to increase the value of the cull co w carcass. Therefore, it was the objective of this research to 1) determine the effect s of realimentation on physical, chemical, and sensory characteristics of key muscles from cull beef cows; 2) Evaluate the consequences of cooler aging on various muscle s from realimented cull beef cows; and 3) Measure the interaction of realimentation and cooler agi ng on sensory traits of multiple muscles from

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107 cull beef cows. It is hypothesized that realimentation and postmortem aging will increase the quality and improve the sensory characteri stics of selected mu scles from cull beef cow carcasses, allowing for increase d value added processing of cull beef cow carcass. Materials and Methods Animal Selection and Treatment Twenty-four beef cows were selected from the two University of Florida beef herds (Gainesville, FL) after being culled from th e herds in late October due to failure to conceive after two consecutive years. Cull cows were selected based upon the criteria that they have had at least two calves in prior seasons, had not tested positive for Johne’s Disease and were not of 100% Angus or 100% Brahman breeding. Cull cows selected for inclusion were weighed, body condition scored (BCS; 1 = severely emaciated, 2 = emaciated, 3 = very thin, 4 = borderline th in condition, 5 = moderate condition, 6 = good condition, 7 = fat, 8 = very fat and 9 = severe ly obese) and dentition was examined to ensure all cows had a sound mouth. Cull cows were subsequently randomly placed into one of three treatment groups (n = 8 each). Cow age, herd of origin, BCS, Johne’s disease score and live weights were simila r for all groups (Table 5-1). The three representative treatments were 1) 0 days on concentrate feed, 2) 42 days on concentrate feed, and 3) 84 days on concentrate feed. A ll cows were previously pastured on common Bahiagrass ( Paspalum ssp. ) and Bermudagrass ( Cynodon ssp. ) throughout the summer and early fall. All cows received pour-on anthelmintic (Eprinex-Ivomec, Merial, Iselin, New Jersey) at a rate of 10 ml per 100 kg, as wa s consistent with dosage recommendations, prior to being fed at the University of Fl orida Beef Teaching Unit (Gainesville, FL). Cows were all housed in a semi drylot envi ronment allowing for 0.06 hectare per cow for

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108 the duration of the feeding period. All cows we re pastured and fed t ogether. Cows were fed from pasture bunks that allowed approxima tely 1 meter of bunk space per cow. As well, ad libitum water and shade canopies were provided at all times. Cows were group bunk fed prior to the start of the feeding tria l at a rate that allowed for 11.36 kg per cow per day after a 7 day diet acclimation period. The cull cow ration composition consisted of 84.5% whole corn, 7.5% cottonseed hulls , 7.5% protein pellet, and 0.05% trace minerals with no additional grass provided. An alysis of the diet s howed that it provided 75.1% total digestible nutrients, 11.9% crude protein, 6.5% crude fi ber, 3.3% fat, 9.9% acid detergent fiber, 16.1% neutral de tergent fiber, 0.17% calcium and 0.28% phosphorus. Ad libitum mineral supplement (Nutrebeef, Nutrena, Cargill Inc., Minneapolis, MN) was also provided at all time s in a covered mineral feeder. Cows were weighed at day 0, day 42 and day 84 of feeding as well as having BCS taken and average daily gains calculated. Carcass and Muscle Treatment At the end of each feeding period the re spective cows were transported to the University of Florida Meats Processing Center (Gainesville, FL) for harvesting and held without feed but ad libitum water 24 hours pr ior to harvesting. Carcasses were not electrically stimulated, had hot carcass we ights (HCW) recorded and were placed in a cooler (0C) after the harvesting process to chill. After the carcass had chilled for 24 hours the left side of each carcass was ribbed at the 12-13th rib juncture and allowed to bloom for 30 minutes prior to co llection of carcass data. Carc ass data collected included HCW, dressing percent (DP) , ribeye area at the 12th rib (REA), fat ove r the eye at the 12th rib (FOE), preliminary yield grade (PYG), pe rcent lean, lean maturity, bone maturity, marbling, lean texture, lean firmness, muscle score, subjective lean color scores (1 =

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109 Extremely bright cherry red; 8 = Extremely dark red), subjective fat color scores (1 = White; 5 = Yellow), and objective CIE L* a* b* lean and fat color measurements (Minolta chromo meter CR 310, Minolta C o. Ltd., Osaka, Japan). Where L* is a measurement of lightness (0 = black, 100 = wh ite), a* is a measurement of red (+) to green (-), and b* is a measurement of yellow (+) to blue (-). The right side of each carcass was fabric ated in a way so that whole muscles could be excised including m. Triceps brachii – long head (LON), m. Triceps brachii – lateral head (LAT) and m. Infraspinatus (INF) from the chuck, m. Longissimus dorsi (LOD) and m. Psoas major (PSO) from the loin, m. Gluteus medius (GLM) from the sirloin and, m. Tensor fascia latae (TFL), m. Rectus femoris (REF) and m. Vastus lateralis (VLS) from the round. Muscles were trimmed to 0.64 cm as a commercial trim, weighed and then trimmed to 0.0 cm fat, denuded of all visibl e connective tissues, reweighed and measured for minimal and maximal depth, length and wi dth (information is presented in Appendix D). The INF was separated medial and l ongitudinal and the thick medial sheet of connective tissue was removed (Flat Iron styl e). Starting at the caudle end of the muscles, 2 steaks were cut (1 for 10 days postmortem aging and 1 for 20 days postmortem aging) 2.54 cm thick perpendicula r and across the grain of the muscle for Warner-Bratzler shear force determination fo r all muscles. From the caudle end of muscle, 4 steaks were cut (2 for 10 days postmortem aging and 2 for 20 days postmortem aging) 2.54 cm thick perpendicular and across the grain of the muscle from the LON, LOD, GLM, and REF for sensory panel evaluation. One steak was cut 2.54 cm thick perpendicular and across the grain of the muscle from the posterior end of the LOD and LON for collagen analysis. One steak was cut 2.54 cm thick perpendicular and across the

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110 grain of the muscle from the posterior e nd of the LON, LOD and GLM for fatty acid analysis. Fatty acid analysis and results wi ll be discussed in chapter 6. Steaks were labeled, vacuum packaged using a Mutivac C500 (Multivac, Inc., Kansas City, MO) vacuum packager and Cryovac heat shrink v acuum bags (Sealed Air Corporation, Saddle Brook, NJ). Steaks were then allowed to age in a cooler at 2 2 C for either 10 or 20 days postmortem. At the end of the require d aging period steaks were stored at -40C until further analysis. Steaks for collagen determination were immediately place in storage at -40C until analyses were conducted. Warner-Bratzler Shear Force Steaks from each muscle designated for Wa rner-Bratzler shear force (WBS) were thawed for 18 hours at 4C. Steaks were then cooked on Farberware Open-Hearth Broilers (Farberware Products, Nashville, TN) that were preheated for 20 min. Steaks were turned once when the internal temperat ure reached 35C and then were allowed to finish cooking until they reached an inte rnal temperature of 71C (AMSA, 1995). Internal temperatures were monitored by c onstantan thermocouples (Omega Engineering, Inc., Stamford, CT) placed in the geometric center of each steak and recorded using a 1100 Labtech Notebook for Windows 1998 (Computer Boards, Inc., Middleboro, MA). Steaks were allowed to cool for 18 hours at 4C. After cooling, 6 cores, 1.27 cm in diameter were removed parallel to the longi tudinal orientation of the muscle fibers. Cores were sheared once perpendicular to the longitudinal orientation of the muscle fibers with a Warner-Bratzler shear head, at a cross-head speed of 200 mm/min, attached to an Instron Universal Testing machin e (Instron Corporation, Canton, MA).

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111 Sensory Attributes Steaks designated for sensory panel evaluati on (SP) were treated and cooked to the same specifications as the WBS samples. Upon reaching 71C internal temperature, steaks were served to panelists while still wa rm. Sensory panelists evaluated 6 samples, 2 sample cubes 1.27 cm2 per sample, served in warmed covered containers on two daily sessions in a positive pressure ventilation r oom with lighting and cubicles designed for objective meat sensory panels. Sampling wa s designed so that at each sitting every panelist was randomly served samples from 0, 42, 84 day treatments and 10 and 20 days of postmortem aging for the same muscle wi thin a carcass. A 7 – 11 member sensory panel trained according to AMSA sensory evaluation guidelines (AMSA, 1995) evaluated each sample for 5 se nsory attributes. The 5 evalua ted sensory traits included: overall tenderness (1 = extremely tough, 2 = very tough, 3 = moderately tough, 4 = slightly tough, 5 = slightly tender, 6 = m oderately tender, 7 = very tender and 8 = extremely tender), overall juic iness (1 = extremely dry, 2 = very dry, 3 = moderately dry, 4 = slightly dry, 5 = slightly juicy, 6 = moderately juicy, 7 = very juicy and 8 = extremely juicy), beef flavor intensity (1 = extremely bland, 2 = very bland, 3 = moderately bland, 4 = slightly bland, 5 = slightly intense, 6 = moderately intens e, 7 = very intense and 8 = extremely intense), off-flavor (1 = extreme o ff-flavor, 2 = strong off-flavor, 3 = moderate off-flavor, 4 = slight off-flavor, 5 = threshol d off-flavor and 6 = no off-flavor detected), and off-flavor descriptor (metallic, grassy, livery, grainy, gamey or other). Off-flavor descriptor results will be discussed in a subsequent chapter (Chapter 6). Collagen Analysis Heat labile soluble collagen, insoluble and total collagen content for the LOD and LON were extracted and separated following the methods outlined by Hill (1966). Five

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112 grams in duplicate from each sample were mixed with strength Ringers solution and heated in a 77C water bath for 63 minutes. Samples were then placed in a centrifuge at 12,000 rpm for 20 minutes at 4C. The supern atant was decanted and the pellet fraction was recentrifuged in strength Ringers. The supernatant was again decanted with the previous supernatant and marked as the sol uble collagen fraction. Th e residue pellet was combined with 25 ml of 6 M HCL and labeled as the insoluble collagen fraction and the supernatant was combined with 20 ml of 12 M HCL and placed in an autoclave at 15 psi and 121C for 18 hr to hydrolyze the proteins. All samples were then filtered with 2 g of 1:2 charcoal:Lewatit Monoplus MP500. Sa mples were then filtered through Whatman #41 filter paper, evaporated and neutralized w ith distilled water and 3 N NaOH to a pH of 6.5. Hydroxyproline determination was carried out following the procedures outlined by Bergman and Loxley (1963) using a Jasc o V-530 spectrophotometer and VWS 580 Spectra Manager for Windows (Tokyo, Japan) to read absorbance at 558 nm. The spectrophotometer was blanked against distille d water. Spectrophotometer readings were determined by standard curves prepared for each day of analysis. Total and fractional collagen content was determined by multip lying the hydroxyproline content of the soluble supernatant by 7.25 and the residua l insoluble fraction hydroxyproline content by 7.52 (Cross et al., 1973). Statistical Analysis The data for live animal traits and car cass characteristics were analyzed as a completely randomized design with animal or carcass as the experimental unit to determine if live trait or car cass characteristic means differe d among the three treatments of time on feed. Animal or carcass was th e experimental unit and carcass or animal nested within treatment was considered a rando m variable and was used as the error term

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113 to test the effects of sources of variati on. The model utilized to test the variance followed: yij + + ai + eij, where yij was the jth observation from the ith feeding treatment, was population mean fo r the live or carcass trait, ai was the effect of days on feed, and eij was the random error effects of animal or carcass within treatment of days on feed. The analysis of collagen content wa s conducted using a split-plot design were carcass was the whole-plot and muscle was th e sub-plot and the e xperimental unit. Carcass within treatment was used as the w hole-plot random error, and muscle x carcass within treatment was the random effect for th e sub-plot of muscle. The split-plot model for collagen content followed: yijkl = + gi + bij + mk + (gm)ik + eijk, where yik was the collagen content (mg/g) or percent of total va lue for the kth muscle in the jth carcass from the ith feeding treatment, was the popul ation mean for collagen analysis, gi was the effect of the ith feeding treatment, bij was the whole-plot random error effect of the jth carcass in the ith treatment, mk was the effect of the kth muscle, (gm)ik was the interaction effect between the ith treatment and kth muscle, eijk was the sub-plot random error of the kth muscle of the jth carcass in the ith treatmen t. The analysis of WarnerBratzler shear force and sensory attributes was conducted using a spli t-split-plot design where carcass was considered the whole-plot, muscle was considered the sub-plot and steak utilized for days of postmortem aging wa s the sub-sub-plot. In this design the steak was considered the experimental unit and th e core for WBS or the cube for sensory analysis was considered the observational unit. For the split-split-plot analysis of WBS and sensory data, carcass within treatment was considered the random effect for the whole-plot of carcass, muscle x carcass nest ed within treatment was the random term for the sub-plot of muscle, and steak nested with in muscle, animal and treatment was

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114 considered the random term for the sub-sub-plot of steak utilized for days of postmortem aging. The split-split-plot model was yijkl = + gi + bij + mk + (gm)ik + eijk + sl + (gs)il + (ms)kl + (gms)ikl + ijkl, where yikl was the WBS or sensory attr ibute value for the lth aged steak in the kth muscle in the jth carcass from the ith feeding treatment, was the population mean for WBS or sensory attributes, gi was the effect of the ith feeding treatment, bij was the whole-plot random error ef fect of the jth carcass in the ith treatment, mk was the effect of the kth muscle, (gm)ik was the interaction effect between the ith treatment and kth muscle, eijk was the sub-plot random e rror of the kth muscle of the jth carcass in the ith treatment, sl was the effect of the lth postmortem aged steak, (gs)il was the interaction effect of the lth aged steak in the ith treatment, (ms)kl was the two-way interaction effect of the lth aged steak in the kth muscle, (gms)ikl was the threeway interaction of the lth aged steak from the kth muscle from the ith treatment, and ijkl was the sub-sub-plot random error associated with the lth aged steak from the kth muscle in the jth carcass from the ith treatment. The mixed procedures of Statistical Analysis System V.9.1 (2002, SAS Inst. Inc., Cary, NC ) were used to test the completely randomized and split-split-plot models. Mean s were separated using the PDIFF option in LSMEANS due to missing values. Differences among means were considered significant at an alpha level 0.05. Results and Discussion Live and Carcass Characteristics Least squares means for live animal perf ormance traits afte r time on feed are presented in Table 5-2. Live weights (LW) were not different (P > 0.05) between 0 and 42 days on feed, however a significant increas e (P < 0.05) in LW occurred by 84 days. A trend similar to LW in the current study wa s seen for BCS. There was no difference (P >

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115 0.05) in BCS between cows fed 0 or 42 days, but there was a significant increase (P < 0.05) in BCS by the time cows were on concentr ate feed for 84 days. Cull cows on feed for 42 days did increase in BCS, 0.7 units from their initial BCS at the beginning of the feeding period. As well, cows on feed for 84 days increased BCS 1.6 units from their initial BCS at the beginning of the trial to finish at a BCS of 6.0 (Table 5-1 and Table 52; comparison from within treatment not shown). Estimated average daily gains (ADG) revealed that there was no difference (P > 0.05) between 0 day and 42 day treatments, but there was a significant differe nce (P < 0.05) in ADG for the cows on feed for 84 days when compared to 0 day and 42 day treatments. Gain to feed ratios (not shown) were 0.03 for cull cows on feed for 42 days and we re significantly higher (P < 0.05) at 0.09 for cull cows that were fed for 84 days. A lthough neither treatment was efficient in converting feed to live weight gain, cull cows fed for 84 days were 3 times more efficient than those fed for 42 days. However, when cull cows were fed for 42 days it was estimated that the carcasses gained 0.98 kg/ d and when cull cows were fed for 84 days the carcasses were estimated to have ga ined 1.10 kg/d when compared to day 0 HCW estimates (obtained from LW in Table 5-1 and figuring a 47.7 % DP from the Day 0 cull cows in Table 5-2). The difference in liv e weight ADG and HCW ADG, and the increase in DP for the cull cows fed for 42 days were at tributed to a shift in weight from rumenal fill to carcass weight that occurred within the first 42 days on feed. Boleman et al. (1996) reporte d that live weights increa sed (P < 0.05) for cull cows fed a concentrate diet at 28, 56, and 84 days on feed. As well, Cranwell et al. (1996b) also reported increased (P < 0.05) cull cow li ve weight as time on feed increased for 0, 28, and 56 days. Similar to the current st udy, Apple (1999) reported that cull cow live

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116 weight increased (P < 0.05) as BCS increased from BCS 5 to 6. Contrary to the current study, Faulkner et al. (1989) reported an in crease (P < 0.05) in cull cow live weights between 0 and 42 days but observed no furthe r significant increases out to 84 days on feed with ADG of 2.74 and 1.60 kg, respectivel y. The difference in live weights recorded for the current study is attributed the low ADG observed for the cows fed for 42 days and the increased ADG observed for the cows fed for 84 days. The cull cows fed 84 days gained more rapidly for the last 42 da ys on feed than the first 42 days (0.75 kg/day vs. 1.23 kg/day, respectively). Matulis et al . (1987) reported cull cows fed concentrate diets had the greatest ADG at 29-56 days on feed and then had decreased ADG between 57 and 84 days on feed. The reasons for the increased gains in the 84 day cull cows, and not the 42 day cows in the present study are not easily explained. One possibility could be the nutritional status of the cows entering the feeding trial. All cows were in a body condition score of 4 or 5 at the beginning of the trial, therefore large compensatory gains were not observed. Another possi bility could be that the transition in di et of 100% forage to a concentrate ration consisting of only 7.5% forage as cottonseed hulls required a greater acclimation period than the 7 days allowed. Sawyer et al. (2004) reported negative ADG and gain:feed ratios for the fi rst 14 days of f eeding. The negative responses observed along with decreases in body weight were assumed to be related to a decrease in gut fill. This coupled with the previous reason could partially explain the low live weight gains for cows dur ing the first 42 days on feed. Least squares means for carcass characteristics are presented in Table 5-2. HCW followed a trend similar to LW with cows on feed for 0 and 42 days having similar (P > 0.05) HCW, and cows on feed for 84 days had significantly heavier (P < 0.05)

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117 HCW. DP increased (P < 0.05) from 0 to 42 days on feed but no further significant increases were observed. The increased carca ss DP of the cows on feed for 42 days (and the numerical increase for those on feed for 84 days) can be explained by the increase in REA, FOE, and carcass muscling that wa s recorded. Even though live and carcass weights were not statistically different at 0 and 42 days, with the increased DP of cull cows that were fed for 42 days it appears th at much of the live weight at 0 days was digestive fill, while at 42 days the cull co ws had more weight in their carcasses. Although REA, FOE, and carcass muscling were only significantly different (P < 0.05) for carcasses from cows fed for 84 days, numeri cal increases were observed in all traits by 42 days on feed. As well, PYG increased significantly (P < 0.05) by 84 days on feed, however, PYG was still under 3 for all trea tments. Boleman et al. (1996) reported increases in FOE, REA, HCW, and yield grade as time on feed increased to 84 days. As well, Cranwell et al. (1996b) also reported increases in HC W, FOE, REA and yield grade as time on feed increased. Bone maturity did not differ (P > 0.05) between any of the three treatments. However, lean maturity was significantly lo wer (P < 0.05) in carcasses from cows fed for 84 days. Lean texture was not different (P > 0.05) between any of the treatments but decreased numerically (became finer in textur e) as time on feed increased from 0 to 84 days. Lean was significantly (P < 0.05) firmer in carcasses from cows that were fed for 84 days compared to carcasses from cows th at were not fed. Marbling score increased significantly (P < 0.05) in carca sses derived from cows fed fo r 84 days when compared to carcasses derived from cows that were slaugh tered directly off pasture. Carcass from cows fed for 42 days exhibited a marbling scor e in the lower end of Slight which was not

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118 different than carcasses from either of the two treatments. When maturity and marbling are coupled together, carcass from both 42 and 84 days on feed treatments exhibited quality grades that would fall into USDA Utili ty, while carcass from cows that were not fed had an average quality grade of USDA Cutter. The increase in cull cow carcass quality from USDA Cutter to USDA Utility or better may be enough of an increase in quality to add value to the carcass (Apple, 1999) . Subjective lean colo r scores show that as time on feed increased the lean in the car cass became brighter (P < 0.05) and became a more desirable cherry red color. CIE color measurements recorded the lean L* as being lighter in color after 42 days on feed when comp ared to carcasses from cull cows that had been on feed for 0 or 84 days. However, the CIE L* value recorded for carcasses from cull cows that were on feed for 84 days was lig hter (P < 0.05) than th e L* value recorded for carcasses from cull cows that did not rece ive a concentrate diet. The CIE a* and b* values are in agreement with the subjective lean color scores showing that the lean became redder and more yellow in color after 42 days on feed and then made nonsignificant (P > 0.05) improvements through 84 da ys of concentrate feeding. A decrease in pigment concentration as was reported by Matulis et al. (1987) or dilution of the pigment concentration due to increased intram uscular fat and muscle proteins could be partly responsible for the lightening of longissimus color. Subjective carcass fat color scores show that as time on feed increased, carcass fat became more desirable and whiter (P < 0.05). As well, CIE color scores revealed that L* decreased (P < 0.05) a* increased (P < 0.05) and b* decreased (P < 0.05) as time on feed increased for each time point. Fat color can affect the value of a carcass and may be correlated to other sensory traits with

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119 yellow fat being indicative of decreased tende rness and increased off-flavors (Hilton et al., 1998). Least squares means for car cass composition are presente d in Table 5-3. Percent carcass fat free lean (CFFL) was similar (P > 0.05) between carcass from cows fed for 0 and 42 days and then decreased (P < 0.05) as time on feed increased to 84 days. CFFL weight was similar (P > 0.05) but increased 18.1 kg between 0 and 42 days on feed and then increased significantly (P < 0.05) by 84 days on feed. However, fat weight increased (P < 0.05) by 42 days on feed and th en again by 84 days on feed. Percent fat was similar (P > 0.05) between 0 and 42 days on feed and then increased (P < 0.05) by 84 days on feed. Lean to fat ratios were highe r in carcasses from cattle on feed for 42 days (5.6) compared those on feed for 84 days ( 3.9). Bone weight remained constant and decreased as a percent of th e total carcass weight as tim e on feed increased. Although there was more lean accretion between 42 a nd 84 days than there was between 0 and 42 days, percent lean decreased by 84 days on feed due to a large increase in fat deposition that occurred between 42 and 84 days on f eed. The findings of the current study are similar to those of Faulkner et al. (1989) who reported increas es in percent soft tissue and percent soft tissue fat at 42 a nd 84 days on concentrate feed for cull cows. Matulis et al. (1987) also reported increases in CFFL weight and carcass fat weight as cull cow time on feed increased from 0 to 84 days. Collagen Content There was not a significant in teraction (P > 0.10) for effect of treatment x muscle on collagen content (mg/g) or percent of total collagen. The main effect of muscle had a significant effect (P < 0.05) on collagen c ontent. LON had more soluble (P < 0.05), insoluble (P < 0.05), and total collagen (P < 0.05) content (mg/g) than the LOD.

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120 However, there was no difference (P > 0.05) in percent soluble or percent insoluble collagen between LON and LOD. Least squares means for the main effect of days on feed are presented for collagen content in Table 5-4. Percent soluble collagen and collagen content (mg/g) were similar (P > 0.05) between 0 and 42 days on feed but increased (P < 0.05) by 84 days on feed. So luble collagen (mg/g) increased by 40% by the time cull cows were on feed for 84 da ys. Total collagen content and insoluble collagen content (mg/g) were not different (P > 0.05) for any of the three feeding times. However, percent insoluble collagen decrease d after cull cows were on feed for 84 days due to the increase in the soluble collagen fraction. Boleman et al. (1996) and Cranwell et al. (1996a) both reported increases in percent soluble collagen as time on feed incr eased. The values for total collagen (mg/g) obtained in the current study are less than t hose found by Miller et al. (1983) in young steers or Cranwell et al. (1996a) for cull co ws, but are in agreem ent with the total collagen (mg/g) values reported by Boleman et al. (1996) for cull cows. Aberle et al. (1981) concluded that cattle fed high-ener gy diets experience rapid rates of protein synthesis and therefore would be expected to produce beef with a high proportion of newly synthesized, heat-liable collagen as is evidenced by the current study. Warner-Bratzler Shear Force Least squares means for all interactions of days on feed x muscle for WarnerBratzler shear force are shown in Table 5-5 and for muscle of the sirloin and round in Figure 5-1, muscles of the loin in Figure 5-2, and muscles of the chuck in Figure 5-3. There was no difference (P > 0.05) in WBS values between treatments for INF, LAT, PSO, REF, and TFL. The GLM was similar (P > 0.05) for WBS value between cows on feed for 0 and 42 days but then decreased (P < 0.05) in WBS value for the cows on feed

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121 for 84 days. The LON increased (P < 0.05) in WBS value between cows fed for 0 and 42 days but then decreased in cows fed for 84 days to become similar to LON values for cull cows on feed for 0 and 42 days. VLS was the only muscle to continuously increase in WBS value as time on feed increased with an increase of 1.0 kg (P < 0.05) occurring between 0 and 84 days on feed. The LOD show ed the most improvement decreasing (P < 0.05) in WBS value 3.70 kg between cows on feed for 0 and 84 days. For cows that did not receive concentrate feed prior to slaught er the LOD was the l east tender (P < 0.05) muscle. After 42 days on feed the VLS was the least tender (P < 0.05) muscle while the LOD was comparable (P > 0.05) to the GLM, LAT, and LON while the INF, PSO, and REF were more tender (P < 0.05) than the L OD. After 84 days on feed the VLS was still the least tender ( P < 0.05) muscle and the LOD was comparable ( P > 0.05) to the GLM, LAT, LON, REF, and TFL. The PSO and INF were similar ( P > 0.05) and more tender ( P < 0.05) than all other muscles after cull cows were on feed for 84 days. Most of the current literature on musc le characteristics of realimented and supplemented cull cows was conducted on the m. Longissimus dorsi (Matulis et al., 1987; Brown and Johnson 1991; Boleman et al., 1996 ; Cranwell et al., 1996a). Brown and Johnson (1991) reported that increased ener gy supplementation did not decrease shear force values for the longissimus muscle in cull cows, however, Miller et al. (1987) did find that increased energy supplemen tation prior to slaughter decreased longissimus shear force. As well, Matulis et al. (1987), Boleman et al. ( 1996) and Cranwell et al. (1996a) all reported that concentrat e feeding of cull cows prio r to slaughter decreased longissimus shear force. The increased tenderness th at was found in the current study, and many others, may be partially attribut ed to the increase in heat lia ble collagen that forms as a

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122 result of increases in lean accretion. This was evidenced in the current study by the increase in soluble collagen by 2.78% after cu ll cows were on a concentrate diet for 84 days (Table 5-4). Bailey (1985) sugges ted that old collagen is not completely catabolized, but for the most part is retained and pushed apart to allow expansion of newly synthesized collagen as lean accreti on occurs, however, this would cause total collagen to increase which was not seen in th e current study. For mu scles other than the longissimus , Dryden et al. (1979) repo rted that realimentation of cull cows prior to slaughter only improved the shear values of two muscles after 108 days on concentrate feed. The main effect means of days of po stmortem aging on WBS are presented in Table 5-6. The only significant interaction th at occurred with days of postmortem aging was the interaction of DOA and muscle (P = 0.0 5). However, the only muscle affect by DOA was the LOD (P < 0.05) which had a WBS value of 7.33 kg after 10 DOA and a WBS value of 6.31 kg after 20 DOA (std. err. = 0.23). The two-way interaction of treatment x DOA and the threeway interaction of treatment x muscle x DOA were not significant effects (P = 0.20 and P = 0.30, respecti vely). The main effect of days of postmortem aging shows that WBS values decr eased (P < 0.05) after 20 days postmortem aging when compared to steaks that were ag ed for 10 days postmortem. Huff-Lonergan et al. (1995) examined the effects of animal age on the degradation of titin and nebulin in beef and found that age influenced the brea kdown of these key proteins. Beef from young animals showed signs of protein degradati on at a faster rate than beef from older animals, therefore, implying that beef fr om older animals my benefit from extended postmortem aging.

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123 Sensory Attributes Least squares means for the main effect s of days on feed and days of postmortem aging for sensory attributes are presented in Table 5-6. No difference ( P > 0.05) was observed for overall tenderness between 0 and 42 days on feed, however, overall tenderness did increase (P < 0.05) after 84 days on feed. Days of postmortem aging did not result in a significant inte raction effect (P > 0.10) with either treatment or muscle when examining sensory attributes. Steaks th at were aged for 20 days postmortem were more tender (P < 0.05) than st eaks aged for 10 days postmortem. Several authors have reported that endogenous enzymes such as lyso zomal proteases and collagenases have the ability to degrade connective tissues in beef when stored postmortem (Dutson et al., 1980; Wu et al., 1981a) which would improve overall tenderness. Although overall sensory tenderness and WBS show ed a significant increase in tenderness, this tenderness increase was only an increase of 0.21 sensor y units and only decreased WBS values by 0.23 kg between 10 and 20 days of postmortem aging. Due to the small magnitude of improvement made by an additional 10 days of postmortem aging, it appears unlikely that endogenous enzymes played a key role in conn ective tissue degradation, if they had it would have been expected to see increases in tenderness of a much larger magnitude than were observed in the current study. Days of postmortem aging did not effect beef flavor intensity (P > 0.10) or sensory off-flavor (P > 0.10). The findings of the current study are somewhat unexpected as postmortem aging may provide and environment conducive to free radical production and lipid oxidation which has been show n to be a precursor to offflavor production (Melton, 1982; Melton, 1983; Farmer, 1994). As well, beef flavor intensity and overall juiciness was not affect ed by days on feed. However, sensory offflavor detection decreased (P < 0.05) after 42 da ys on feed and then continued to decrease

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124 minimally after 84 days on feed. Feed source is the most important environmental factor affecting off-flavor production (S hahidi et al., 1986). Melton (1990) reported that highenergy grain diets tend to produce a more accepta ble flavor in red meats than low-energy forage or grass diets. The main effect of muscle on sensory attr ibutes (Table 5-7) reveals that the REF and GLM were the most tender (P < 0.05) of the four muscles examined while the LOD was the least tender (P < 0.05). GLM had the most intense (P < 0.05) beef flavor while LOD and REF exhibited the least intense beef flavor, but all values for beef flavor intensity were within the slightly intens e range. There was no difference between muscles for overall juiciness score with all muscles examined ranking as slightly juicy. The only muscles that differed in off-flavor score were the LOD and LON. The LOD was scored as having more (P < 0.05) off-flavor than the LON. The REF and GLM were similar in off-flavor to all of the muscles examined. There was a significant interaction between days on concentrate feed and muscle for sensory overall tenderness (Figure 5-4). Three of the four muscles examined (GLM , LOD, and LON) increased (P < 0.05) in sensory tenderness as days on feed increas ed. The REF increased numerically in tenderness rating although not significantly. The LOD was the least tender (P < 0.05) muscle after 0 and 42 days on feed and exhibited the most improvement becoming similar to the LON and REF after cows were on feed for 84 days. Dryden et al. (1979) reported an increase in sensory tenderness for two of the four muscles studied for beef from realimented cull cows but that realimen tation did not affect sensory juiciness or flavor scores.

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125 Implications Realimentation of cull cows prior to slaughter does impr ove carcass characteristics and muscle quality attributes. Several musc les from the chuck and round are comparable if not more desirable to the LOD in tenderne ss and sensory characteri stics. Therefore, there are several muscles that would make a viable source for intermediately priced quality beef products from realimented cull cows. The increased product utilization of these muscles could increase the value of cull cows to both the producers and meat processors. Maximum carcass a nd muscle effects were reali zed after cull cows were on feed for 84 days and aged for 20 days postmor tem. This study shows that processors can age meat from cull cow carcasses for at leas t 20 days postmortem with out any detriment to off-flavor or beef flavor intensity. More research is warranted to examine th e effects of concentrate feeding for a time period between 42 and 84 days on carcass and mu scle quality. As time on feed increased fat deposition became a predominating factor in increased weight gains. Examining mechanisms to alter lean and fat accretion le vels in favor of lean accretion may aid in making short-term realimentation of cull co ws a more efficient production practice.

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126 Table 5-1. Least squares means of live traits prior to cull cow feeding Treatment1 Item 0 Days 42 Days 84 Days SEM P > F Herd2 2.25 2.50 2.00 0.36 0.62 Age, yr 5.25 5.50 5.63 0.47 0.85 Johne’s3 0.25 0.13 0.00 0.16 0.56 Live wt, kg 463.3 462.2 459.2 19.24 0.99 BCS4 4.9 4.7 4.4 0.20 0.22 10, 42, and 84 days = time cull cows spent on concentrate diet. 2Designated from the University of Florida b eef cattle herds 2 and 3 which are the Boston Farm – Santa Fe River Ranch and Beef Res earch Unit made up of Angus, Brahman and reciprocal crosses. 3Score of 4 is three positive blood tests fo r Johne’s disease, scores of 0 and 1 are considered Johne’s negative, 2 is suspected a nd scores of 3 – 4 are definitively positive. 4Body condition score: 1 = Severely emaciated, 2 = emaciated, 3 = very thin condition, 4 = borderline thin condition, 5 = moderate d condition, 6 = good condition, 7 = fat condition, 8 = very fat and 9 = Severely obese.

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127 Table 5-2. Least squares means for live performance and carcass characteristics Treatment2 Trait1 0 Days 42 Days 84 Days SEM Live Live Wt, kg 480.8b 490.0b 568.6a 22.47 ADG, kg 0.00b 0.37b 0.99a 0.16 BCS3 4.9b 5.4b 6.0a 0.17 Carcass Hot Carcass Wt, kg 229.3b 261.6b 311.1a 12.61 Dressing Percent 47.7b 53.4a 54.8a 1.15 Ribeye area, cm2 64.35b 72.02ab 78.87a 2.89 Fat thickness, cm 0.24b 0.41b 0.95a 0.11 PYG 2.22b 2.48b 2.98a 0.12 Lean maturity D 63a D 95a C 60b 20.39 Bone maturity D 61 D 90 E 14 26.15 Lean color Subjective4 5.3a 4.9ab 4.1b 0.30 L* 35.68c 37.75a 36.97b 0.15 a* 24.48b 25.97a 26.12a 0.16 b* 9.72b 10.66a 10.50a 0.09 Fat color Subjective5 5.0c 3.9b 2.8a 0.29 L* 78.85a 76.15b 74.13c 0.55 a* 3.17c 9.90b 12.60a 0.57 b* 27.92a 24.64b 22.70c 0.55 Marbling6 255b 312ab 359a 23.93 Lean texture7 4.5 4.3 3.8 0.28 Lean firmness7 3.8a 2.6ab 2.4b 0.37 Muscling8 388b 488b 650a 53.31 1ADG = Average daily gain, BCS = Body cond ition score; PYG = Preliminary yield grade. 20, 42, and 84 days = time cull cows spent on concentrate diet. 3Body condition score: 1 = severely emaciate d, 2 = emaciated, 3 = very thin condition, 4 = borderline thin condition, 5 = moderate d condition, 6 = good condition, 7 = fat condition, 8 = very fat and 9 = severely obese. 41 = extremely dark red, 2 = dark red, 3 = mode rately dark red, 4 = slightly dark cherry red, 5 = slightly bright cherry red, 6 = moderate ly bright cherry red, 7 = bright cherry red, 8 = extremely bright cherry red. 51 = white, 2 = creamy white, 3 = slightly ye llow, 4 = moderately yellow, 5 = yellow. 6100 = Practically devoid, 200 = Traces, 300 = Slight, 400 = Small, 500 = Modest, 600 = Moderate, 700 = Slightly abunda nt, 800 = Moderately abundant. 71= very fine; very firm, 2 = fine; firm, 3 = sli ghtly fine; slightly firm, 4 = slightly course; slightly soft and 5 = course, soft. 8100 = light-, 200 = lighto, 300 = light+, 400 = medium-, 500 = mediumo, 600 = medium+, 700 = heavy-, 800 = heavyo, 900 = heavy+.

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128 abcLeast squares means in the same row having di fferent superscripts are significant at P < 0.05. Table 5-3. Least squares means for carcass composition1 Treatment2 Trait 0 Days 42 Days 84 Days SEM CFFL3 % 69.14a 67.80a 65.10b 0.80 Fat3 % 8.81b 11.82b 16.50a 1.17 Bone3 % 17.29a 15.62b 13.45c 0.56 CFFL4, kg 155.2b 173.3b 197.9a 7.78 Fat4, kg 19.9b 31.0a 50.7a 4.07 Bone4, kg 38.6 39.6 40.9 1.81 Percent lean 86.44a 85.05ab 82.92b 0.94 1CFFL = Carcass fat free lean. 20, 42, and 84 days = time cull cows spent on concentrate diet. 3Values calculated by the equati ons of Johnson and Rogers (1997). 4Values calculated by multiplying percent of carcass composition by HCW. abLeast squares means in the same row having di fferent superscripts are significant at P < 0.05.

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129 Table 5-4. Treatment main effect least squares means for collagen content Treatment1 Trait 0 Days 42 Days 84 Days SEM Soluble2 % 2.69b 3.32b 5.48a 0.36 Insoluble2 % 97.31a 96.68a 94.52b 0.36 Soluble mg/g 0.09b 0.09b 0.15a 0.01 Insoluble mg/g 3.54 2.64 2.85 0.31 Total mg/g 3.64 2.73 3.01 0.32 10, 42, 84 days = time cull cows spent on concentrate diet. 2Expressed as a percen t of total collagen. abLeast squares means in the same row having di fferent superscripts are significant at P < 0.05.

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130 Table 5-5. Least squares means for Warner-Bratzler2shear force interaction1 of treatment by muscle Treatment3 Muscle4 0 Days 42 Days 84 Days GLM 6.09a,vw 6.59a,w 4.61b,y INF 3.37a,z 3.25a,z 3.62a,z LAT 5.28a,wx 6.02a,wx 5.54a,x LOD 9.00a,u 6.15b,wx 5.30b,xy LON 5.32b,wx 6.26a,wx 5.61ab,x PSO 3.17a,z 2.78a,z 3.19a,z REF 4.32a,y 4.63a,y 5.25a,xy TFL 4.78a,xy 5.65a,x 5.21a,xy VLS 6.79b,v 7.54ab,v 7.79a,w 1Standard error of least squa res means for all treatment by muscle interactions = 0.33. 2Warner-Bratzler shear force measurements are in kg. 30, 42, and 84 days = time cull cows spent on concentrate diet. 4GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TFL = Tensor fasciae latae , VLS = Vastus lateralis . abLeast squares means in the same row having di fferent superscripts are significant at P < 0.05. uvwxyzLeast squares means in the same column having different superscripts are significant at P < 0.05.

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131 0 1 2 3 4 5 6 7 8 9 0 Days42 Days84 Days Days on ConcentrateWarner-Bratzler Shear, kg GLM REF TFL VLS Figure 5-1. Warner-Bratzler shear force least squares means for the interaction of treat ment by muscle for muscles of the sirlo in and round.

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132 0 2 4 6 8 10 0 Days42 Days84 Days Days on ConcentrateWarner-Bratzler Shear, kg LOD PSO Figure 5-2. Warner-Bratzler shear force least squares means for the interaction of treat ment by muscle for muscles of the loin.

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133 0 1 2 3 4 5 6 7 0 Days42 Days84 Days Days on ConcentrateWarner-Bratzler Shear, kg INF LAT LON Figure 5-3. Warner-Bratzler shear force least squares means for the interaction of treat ment by muscle for muscles of the chuck .

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134Table 5-6. Warner-Bratzler shear fo rce and sensory attribute least squares means fo r the main effects of treatment and days of aging Treatment1 Days of Aging Trait 0 Days 42 Days 84 Days SEM 10 Days 20 Days SEM Warner-Bratzler shear, kg 5.35a 5.43a 5.13a 0.17 5.42y 5.19z 0.11 Overall tenderness2 4.27b 4.47b 4.99a 0.13 4.47z 4.68y 0.08 Beef flavor intensity2 5.32 5.27 5.49 0.07 5.33 5.39 0.05 Overall juiciness2 5.21 4.99 4.99 0.09 5.08 5.05 0.07 Off-flavor3 5.10b 5.45a 5.49a 0.05 5.34 5.36 0.04 10, 42, and 84 days = time cull cows spent on concentrate diet. 21 = extremely tough, extremely bland, extremely dry; 2 = very t ough, very bland, very dry; 3 = m oderately tough, moderately bla nd, moderately dry; 4 = slightly t ough, slightly bland, slightly dry; 5 = slightly tender, slightly intense, s lightly juicy; 6 = mo derately tender, moderately intense, moderately juicy; 7 = very tender, very intense, very juicy and 8 = extremely tender, extremely int ense, extremely juicy. 31 = extreme off-flavor, 2 = strong off-flavor , 3 = moderate off-flavor, 4 = slight offflavor, 5 = threshold off-flavor and 6 = No offflavor detected. abLeast squares means in same row for treatments havi ng different superscripts are significant at P < 0.05. yzLeast squares means in same row for days of aging having different superscripts are significant at P < 0.05.

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135Table 5-7. Warner-Bratzler shear force and sensory attribute least squares m eans for the main effect of muscle Muscle1 Trait GLM INF LAT LOD LON PSO REF TFL VLS SEM Warner-Bratzler shear, kg 5.76c 3.41f 5.61cd 6.82b 5.73c 3.05f 4.73e 5.22de 7.37a 0.19 Overall tenderness2 4.83a ----4.01c 4.57b --4.90a ----0.10 Beef flavor intensity2 5.67a ----5.11c 5.48b --5.03c ----0.07 Overall juciness2 5.12 ----4.96 5.07 --5.11 ----0.09 Off-flavor3 5.33ab ----5.24b 5.48a --5.33ab ----0.05 1GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii long head, PSO = Psoas major , REF = Rectus femoris , TFL = Tensor fasciae latae , VLS = Vastus lateralis . 21 = extremely tough, extremely bland, extremely dry; 2 = very t ough, very bland, very dry; 3 = m oderately tough, moderately bla nd, moderately dry; 4 = slightly t ough, slightly bland, slightly dry; 5 = slightly tender, slightly intense, s lightly juicy; 6 = mo derately tender, moderately intense, moderately juicy; 7 = very tender, very intense, very juicy and 8 = extremely tender, extremely int ense, extremely juicy. 31 = extreme off-flavor, 2 = strong off-flavor , 3 = moderate off-flavor, 4 = slight offflavor, 5 = threshold off-flavor and 6 = No offflavor detected. abcdefLeast squares means in the same row having di fferent superscripts ar e significant at P < 0.05.

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136 0 1 2 3 4 5 6 0 Days42 Days84 Days Days on ConcentrateOverall Tenderness GLM LOD LON REF Figure 5-4. Overall sensory tenderness1 least squares means2 for the interaction of treatment by muscle 11 = Extremely tough, 8 = Extremely tender. 2Standard error for least squares means = 0.18.

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137 CHAPTER 6 EFFECT OF DAYS ON CONCENTR ATE FEED ON SENSORY OFF-FLAVOR SCORE, OFF-FLAVOR DESCRIPTOR AND FATTY ACID PROFILES FOR SELECTED MUSCLES FROM CULL BEEF COWS Introduction Meat palatability is a st rong determinant in whether or not a consumer will repurchase a specific type of meat. Flavor is strongly associated w ith the perception of meat palatability and is one of the most impor tant quality attributes. Flavor is a general term used to define the taste, aroma, umami, and pressureand heat sensitive areas of the mouth (Moody, 1983). Flavor consists of tast e-active compounds, flavor enhancers and aroma components with over 880 compounds presen tly identified in cooked beef alone (Macleod, 1998). Although taste-active and flavor enha ncing compounds influence cooked meat flavor, it is the volatile compounds formed during cooking that determine the aroma attributes and contribute the most to the char acteristic flavor of meat (Mottram, 1998). Many of the aroma compounds in meat are generated from precursors during cooking, with one of the primary reactions being that of lipid oxidation and degradation (Macleod, 1998), especially the thermal oxidation of long-chain fatty acids (Farmer, 1994). When thermal oxidation of long-chain fatty acids occurs, that oxidati on can contribute to undesirable flavors (Mottram, 1987). In lean meat, intramuscular triglyceride s and phospholipids ar e quantitatively the dominant forms of lipid. Several researchers have shown that diet affects the fatty acid profiles present in lean meat tissues (Elmore et al., 2004; Re alini et al., 2004; Nuernberg

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138 et al., 2005). Feed source is the most impor tant environmental factor influencing meat flavor (Shahidi et al., 1986), with high-ener gy grain diets producing red meat with a more acceptable flavor (Melton, 1990) and less off-fla vor (Hedrick et al., 1983; Larick et al., 1987; Bennett et al., 1995) than lowenergy forage or grass diets. When examining alternative production pract ices, such as short term feeding, to increase the value and utilization of cull co w meat it is economically important to know how and if the practice will impact the meat quality derived from cows. Knowing how short-term feeding will aff ect (off-) flavor production a nd precursory compounds such as fatty acid profiles could aid in further pro cessing decisions, allowing the optimal value and utilization from the cull cow carcass to be obtained. Much work has been conducted examining the effects of diet on flavor of beef alluding to breakdown products from fatty acids as the primary source for volatile di fferences. Larick and Turner (1990b) found that certain lexicon descript ors were correlated with satu rated and polyunsaturated fatty acids in young heifers. However, little work has been conducted to examine if the fatty acid profiles in cull cow meat are directly re sponsible for (off-) fla vor production. It was therefore the objective of this research to ch aracterize how short-term concentrate feeding affects off-flavor production and fatty acid prof iles that may contri bute to off-flavor production upon thermal oxidation. It is hypothesized that through short-term concentrate feeding, the incidence and stre ngth of off-flavors will decrease due to alterations in fatty acid profiles. Materials and Methods Animal Selection and Treatment Twenty-four beef cows were selected from the two University of Florida beef herds (Gainesville, FL) after being culled from th e herds in late October due to failure to

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139 conceive after two consecutive years. Cull cows were selected based upon the criteria that they have had at least two calves in prior seasons, had not tested positive for Johne’s Disease and were not of 100% Angus or 100% Brahman breeding. Cull cows selected for inclusion were weighed, body condition scored (BCS; 1 = severely emaciated, 2 = emaciated, 3 = very thin, 4 = borderline th in condition, 5 = moderate condition, 6 = good condition, 7 = fat, 8 = very fat and 9 = severe ly obese) and dentition was examined to ensure all cows had a sound mouth. Cull cows were subsequently randomly placed into one of three treatment groups (n = 8 each). Cow age, herd of origin, BCS, Johne’s disease score and live weights were simila r for all groups (Table 5-1). The three representative treatments were 1) 0 days on concentrate feed, 2) 42 days on concentrate feed, and 3) 84 days on concentrate feed. A ll cows were previously pastured on common Bahiagrass ( Paspalum ssp. ) and Bermudagrass ( Cynodon ssp. ) throughout the summer and early fall. All cows received pour-on anthelmintic (Eprinex-Ivomec, Merial, Iselin, New Jersey) at a rate of 10 ml per 100 kg, as wa s consistent with dosage recommendations, prior to being fed at the University of Fl orida Beef Teaching Unit (Gainesville, FL). Cows were all housed in a semi drylot envi ronment allowing for 0.06 hectare per cow for the duration of the feeding period. All cows we re pastured and fed t ogether. Cows were fed from pasture bunks that allowed approxima tely 1 meter of bunk space per cow. As well, ad libitum water and shade canopies were provided at all times. Cows were group bunk fed prior to the start of the feeding tria l at a rate that allowed for 11.36 kg per cow per day after a 7 day diet acclimation period. The cull cow ration composition consisted of 84.5% whole corn, 7.5% cottonseed hulls , 7.5% protein pellet, and 0.05% trace

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140 minerals with no additional grass provided. An alysis of the diet s howed that it provided 75.1% total digestible nutrients, 11.9% crude protein, 6.5% crude fi ber, 3.3% fat, 9.9% acid detergent fiber, 16.1% neutral de tergent fiber, 0.17% calcium and 0.28% phosphorus. Ad libitum mineral supplement (Nutrebeef, Nutrena, Cargill Inc., Minneapolis, MN) was also provided at all time s in a covered mineral feeder. Cows were weighed at day 0, day 42 and day 84 of feeding as well as having BCS taken and average daily gains calculated. Data presented in Chapter 5. Carcass and Muscle Treatment At the end of each feeding period the re spective cows were transported to the University of Florida Meats Processing Center (Gainesville, FL) for harvesting and held without feed but ad libitum water 24 hours pr ior to harvesting. Carcasses were not electrically stimulated, had hot carcass we ights (HCW) recorded and were placed in a cooler (0C) after the harvesting process to chill. After the carcass had chilled for 24 hours the left side of each carcass was ribbed at the 12-13th rib juncture and allowed to bloom for 30 minutes prior to co llection of carcass data. Carc ass data collected included HCW, dressing percent (DP) , ribeye area at the 12th rib (REA), fat ove r the eye at the 12th rib (FOE), preliminary yield grade (PYG), pe rcent lean, lean maturity, bone maturity, marbling, lean texture, lean firmness, muscle score, subjective lean color scores (1 = Extremely bright cherry red; 8 = Extremely dark red), subjective fat color scores (1 = White; 5 = Yellow), and objective CIE L* a* b* lean and fat color measurements (Minolta chromo meter CR 310, Minolta C o. Ltd., Osaka, Japan). Where L* is a measurement of lightness (0 = black, 100 = wh ite), a* is a measurement of red (+) to green (-), and b* is a measurement of yellow (+ ) to blue (-). Data presented in Chapter 5.

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141 The right side of each carcass was fabric ated in a way so that whole muscles could be excised including m. Triceps brachii – long head (LON), m. Triceps brachii – lateral head (LAT) and m. Infraspinatus (INF) from the chuck, m. Longissimus dorsi (LOD) and m. Psoas major (PSO) from the loin, m. Gluteus medius (GLM) from the sirloin and, m. Tensor fascia latae (TFL), m. Rectus femoris (REF) and m. Vastus lateralis (VLS) from the round. Muscles were trimmed to 0.64 cm as a commercial trim, weighed and then trimmed to 0.0 cm fat, denuded of all visibl e connective tissues, reweighed and measured for minimal and maximal depth, length and wi dth (information is presented in Appendix D). The INF was separated medial and l ongitudinal and the thick medial sheet of connective tissue was removed (Flat Iron styl e). Starting at the caudle end of the muscles, 2 steaks were cut (1 for 10 days postmortem aging and 1 for 20 days postmortem aging) 2.54 cm thick perpendicula r and across the grain of the muscle for Warner-Bratzler shear force determination for all muscles (Chapter 5). From the caudle end of muscle, 4 steaks were cut (2 for 10 days postmortem aging and 2 for 20 days postmortem aging) 2.54 cm thick perpendicular and across the grain of the muscle from the LON, LOD, GLM, and REF for sensory pane l evaluation (Chapter 5). One steak was cut 2.54 cm thick perpendi cular and across the gr ain of the muscle from the posterior end of the LOD and LON for collagen analysis (C hapter 5). One steak was cut 2.54 cm thick perpendicular and across the grain of the musc le from the posterior end of the LON, LOD and GLM for fatty acid analysis. Steaks we re labeled, vacuum packaged using a Mutivac C500 (Multivac, Inc., Kansas City, MO) v acuum packager and Cryovac heat shrink vacuum bags (Sealed Air Corporation, Saddle Brook, NJ). Steaks were then allowed to age in a cooler at 2 2C for either 10 or 20 days postmortem. At the end of the required

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142 aging period steaks were stored at -40C until further analysis. Steaks for collagen determination were immediately place in st orage at -40C until an alyses were conducted. Sensory Off-flavor Steaks designated for sensory panel eval uation (SP) were thawed for 18 hours at 4C. Steaks were then cooked on Farber ware Open-Hearth Broilers (Farberware Products, Nashville, TN) that were preheate d for 20 min. Steaks were turned once when the internal temperature reached 35C and then were allowed to finish cooking until they reached an internal temperature of 71C. Internal temperatures were monitored by constantan thermocouples (Omega Engineer ing, Inc., Stamford, CT) placed in the geometric center of each steak and r ecorded using a 1100 Labtech Notebook for Windows 1998 (Computer Boards, Inc., Middl eboro, MA). Upon reaching 71C internal temperature, steaks were served to panelists while still warm. Sensory panelists evaluated 6 samples, 2 sample cubes 1.27 cm2 per sample, served in warmed covered containers on two daily sessions in a positive pressure ventilation room with lighting and cubicles designed for objective meat sensory panels. Sampling was designed so that at each sitting every panelist was randomly se rved samples from 0, 42, 84 day treatments and 10 and 20 days of postmortem aging for the same muscle within a carcass. A 7 – 11 member sensory panel trained according to AMSA sensory evaluation guidelines (AMSA, 1995) evaluated each sample for 5 sens ory attributes. The 5 evaluated sensory traits included: overall tende rness (1 = extremely tough, 2 = very tough, 3 = moderately tough, 4 = slightly tough, 5 = slig htly tender, 6 = moderately tender, 7 = very tender and 8 = extremely tender), overall juiciness (1 = extremely dry, 2 = very dry, 3 = moderately dry, 4 = slightly dry, 5 = sli ghtly juicy, 6 = moderately ju icy, 7 = very juicy and 8 = extremely juicy), beef flavor intensity (1 = extremely bland, 2 = very bland, 3 =

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143 moderately bland, 4 = slightly bland, 5 = slig htly intense, 6 = mode rately intense, 7 = very intense and 8 = extremely intense), off-fl avor (1 = extreme off-flavor, 2 = strong offflavor, 3 = moderate off-flavor , 4 = slight off-flavor, 5 = th reshold off-flavor and 6 = no off-flavor detected), and offflavor descriptor (metallic, grassy, livery, grainy, gamey or other). Data for overall tenderness, beef flavor intensity and overall juiciness were presented in Chapter 5. Fatty Acid Extraction Fatty acids were extracted from muscle tissues in duplicate following modified methods outlined by Bligh and Dyer (1959) as a modification of Folch et al. (1957). Steaks from the LON, LOD and GLM for fatty ac id analysis were transferred from -40C storage to a -10C freezer for 24 hours prior to analysis. Steaks were allowed to partially thaw at 4C for two hours the morning of fatty acid extraction. Steaks were then cubed by hand and blended (Braun Multiquick homogenizer 4191, Proctor and Gamble, Cincinnati, Ohio) until fine ly ground. The homogenizer was thoroughly cleaned between samples. Duplicate 50 g samples were weighed and blended with 150 ml of 2:1 chloroform:methanol for 2 minutes in stomacher bags. An additional 50 ml of chloroform was added and the sample was blended for an additional 30 seconds. Then 25 ml of distilled water was a dded and the sample was blended for 30 seconds. The sample and liquid was filtered through Whatman No. 1 filter paper under suction with a Buchner funnel. The filter paper and residue was re-e xtracted with 100 ml of chloroform for 30 seconds and filtered as previously described. The stomacher bag was rinsed with 25 ml of chloroform, filtered, and the filtrates were combined in a 500 ml separatory funnel. The filtrate was allowed to separate into bi layers for 4 hours after which the chloroform portion containing the lipid fract ion was transferred to a 500 ml evaporating flask. The

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144 chloroform was removed by rotary evaporation in a 60C water bath under slight suction. Once the majority of chloroform was evaporat ed (~ 20 minutes) evaporating flasks were transferred to a glass bead bath preheated to 60C and evaporated to completion under nitrogen. Weight of lipid and flask was s ubtracted from initial flask weight and was calculated as total lipid weight in meat (mg/g). Duplicate 40 mg lipid aliquots were we ighed from each extraction and placed in vials with 4 ml chloroform and caped with Teflon-lined caps and stored at -20C until methylation. Methylation (formation of fa tty acid methyl esters, FAME) was preformed the morning samples were placed in the gas chromatography (GC) machine (CP – 3800, Varian Inc., Palo Alto, Califor nia) for analysis. Samples were allowed to come to room temperature for 30 minutes. One ml of lipid in chloroform and 0.2 ml of Meth-Prep 2 (0.2 N m-trifloro methyl phenyl, AllTech Asso ciates, Deerfield, Illinois) were combined into a 2 ml auto sample vial, which was crimped tight and allowed to rest for 30 minutes in order to allow methylation to occur. Samples were then ready for GC injection. Production of FAME by Meth-Prep 2 was preferred over FAME production under heat due the possible loss and transfiguration of long chain polyunsaturated fatty acids that may occur with heat (Kramer et al., 1997). Fatty Acid Methyl Ester Analysis FAME were analyzed by injection into a CP – 3800 Gas Chromatograph (Varian, Inc., Palo Alto, California) with a WCOT fused silica column (CP – SIL 88, length 100 m, internal diameter 0.25 mm) with a flow ra te of 5.0 ml/min (Varian, Inc., Palo Alto, California). The carrier gas was helium with a pressure of 29.5 psi (one minute), 35.4 psi (0.42 psi/minute, total of 45 minutes), and 37.9 psi (0.17 psi/minute, held for 50 minutes, totaling 110 minutes). The temperature pr ogram used was: 120C for one minute,

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145 increased to 190C at a rate of 5C/minute and held at 190C for 30 minutes (totaling 45 minutes). The temperature was then increase d to 220C at a rate of 2C/minute and held at 220C for 50 minutes, allowing for a tota l run time of 110 minutes. FAME were identified by comparison of peak rete ntion times to known standards (AllTech Associates, Deerfield, Illinois) injected at a rate of one standard injection per 10 FAME samples. Statistical Analysis Days of postmortem aging did not have a sign ificant effect on sensory off-flavor (P > 0.05; chapter 5). Therefore sensory data we re pooled for this experiment and analyzed as a completely randomized split-plot desi gn where carcass was considered the wholeplot and muscle was the sub-pl ot and experimental unit with sensory panel cube as the observational unit. As well, a split-plot de sign was used for the analysis of fatty acid composition where carcass was the whole-plot and muscle was the split-plot and experimental and observational unit. Car cass nested within slaughter group was considered the random effect of the wholeplot and muscle x carcass nested within slaughter group was considered the random te rm for the sub-plot of muscle for both sensory off-flavor and fatty acid compositi on analysis. The model utilized followed yijk = + gi + bij + mk + (gm)ik + eijk, where yijk was the sensory off-flavor or fatty acid value for muscle k in animal j for feeding tr eatment i, was the population mean, gi was the effect of the ith treatment, bij was the random error effect of carcass j in the ith feeding treatment, mk was the effect of the kth muscle, (gm)ik was the interaction effect between feeding treatment i and muscle k, and eijk was the sub-plot random error of the kth muscle of the jth carcass in the ith treatment. Th e Mixed procedures of Statistical Analysis System V. 9.1 (2002, SAS Inst. Inc., Cary, NC) were used to test th e split-plot models.

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146 Means were separated using the PDIFF op tion in LSMEANS due to missing values. Differences among means were considered sign ificant at alpha leve l 0.05. Chi-square, Frequency procedures of Statistical Analys is System V. 9.1 (2002, SAS Inst. Inc., Cary, NC) were used to test the frequency distribut ion of off-flavor descriptors for the main effects of feeding treatment and muscle. Frequency differences were considered significant at alpha level 0.05 for th e Pearson chi-square statistic. To aid in the determination of the relati onship between fatty acids and off-flavor production, principal components analysis (PCA) was performed via Princomp procedures of Statistical Analysis System V. 9.1 (2002, SAS Inst. Inc., Cary, NC). Principal components were retained for furt her examination when Eigen vectors were greater than one. The Reg procedures of St atistical Analysis System V. 9.1 (2002, SAS Inst. Inc., Cary, NC) were then utilized with off-flavor as the de pendant variable and either the principal component loading or fatty acids as the independent variables. As well, the Reg procedures of Statistical An alysis System V. 9.1 (2002, SAS Inst. Inc., Cary, NC) was used to test summary and rati o variables as independe nt variables and offflavor as the dependant variable. Effects of fatty acids on sens ory off-flavor were considered significant at alpha level 0.05. Results and Discussion Sensory Off-flavor Days of postmortem aging (DOA) did not significantly affect (P = 0.65) sensory off-flavor scores. As well, the two way in teractions of DOA and muscle (P = 0.73) and DOA and treatment (P = 0.86) on off-flavor scor es were not significant. In agreement, Sapp et al. (1999) reported that aging beef for 7 to 21 days postmortem from animals fed grass, concentrate or a combin ation of the two did not sign ificantly affect sensory off-

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147 flavor detection. French et al. (2001) found that feeding eith er forages or concentrates did not affect flavor profil es, but that increased postmo rtem aging improved sensory flavor profiles in carcass from young steers. In a review, Melton (1983) reported more researchers found that postmortem aging in creased off-flavor pr oduction in grass-fed cattle when compared to grain-fed cattle. The reason for the differences between the two diet types was attributed to greater lipid oxidation products in the steaks of grass-fed cattle. The main effect of treatment did significan tly (P < 0.01) impact sensory off-flavor score and is presented in Tabl e 6-1 with the frequency of detected off-flavors. Offflavors became less pronounced in steaks from cull cows that were fed for 42 and 84 days than steaks from cull cows that did not receive a concentrate diet prio r to slaughter. Most of the decrease in off-flavor occurred afte r 42 days on a concentrate diet with minimal decreases after 84 days, although all detected leve ls were at threshold values. Boleman et al., (1996) reported similar finding s to those in the present st udy, when they fed cull cows a concentrate diet for 28 days off-flavor inte nsity decreased (P < 0.05) when compared to loin steaks from cull cows that did not rece ive any concentrate. Off-flavor intensity continued to decrease (P > 0.05) up to 84 da ys on concentrate. Faulkner et al. (1989) found that feeding cull cows a concentrate di et for 0, 42, or 84 days did not alter offflavor scores in loin steaks. The distribut ion of off-flavors show s that the number of samples with detectable off-flavors greatly decreased (P < 0.01) from 0 to 42 days on feed and then only decreased by one more per centage point with an additional 42 days on feed. The descriptors of grassy and gamey we re the highest recorded off-flavors for all treatments, but decreased as days on feed on increased. These findings are in agreement

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148 with Larick et al. (1987), w ho found that as time on concentr ate diet increa sed detection of grassy off-flavor decreased after 56, 84 and 112 days on feed in meat from yearling steers. Grass fed cattle tended to have highe r concentrations of PUFA (especially C18:3, C20:3, C20:4, and C22:5) like in the present study, it stands to reason that the thermal oxidation of these PUFA may contribute to incr eased levels of off-flavors described as grassy and fishy (Melton, 1983; Vatansever et al., 2000). The descriptors of metallic, livery, and grainy decreased between 0 and 42 da ys on feed but then slightly increased after 84 days on feed. Likewise, others have reported an increase in livery off-flavor intensity as concentrate feeding increased from 0 to 84 days (M elton et al., 1982) in young steers. The main effect of muscle was significan t (P < 0.05) for sensory off-flavor score and is presented in Table 6-2 with the freque ncy of detected off-flavors for each muscle. The GLM and REF were similar to each other and to the LOD and LON. Although differences did exist between the LOD and LO N these differences were small (0.24) and all values were between threshold levels a nd no off-flavors being de tected. It appears that diet was a more important factor in offflavor score than was muscle. Crouse et al. (1984) who found that diet did not impact fla vor intensities reported that muscle was a significant factor in flavor in tensity. Contrary to the current research, Dryden et al. (1979) reported that neither di et nor muscle had an effect on flavor production. The Chisquare distribution shows that the LOD had mo re samples with off-flavor detection than any other sample. The LOD had approximate ly 10% more samples with off-flavor detection than did the REF in which 33.7% of samples exhibited some off-flavor characteristics. Similar to the distribution of the main effect of treatment, grassy and

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149 gamey were the two most common off-flavor descriptors for all four muscles while grainy had smallest frequency accounting for less than 1% of all samples. However, Rhee et al. (2004) reported that the LOD has less off-flavor than the REF or the GLM when they were examining the variation in palatability among various steaks from young steers. Fatty Acid Composition Fatty acid summary and ratio variables ar e presented in Table 6-3 and individual fatty acid content (mg/100g) is presented in Table 6-4. Treatment x muscle interactions were present for total lipid content (mg/100g). Therefore, treatment did not have a uniform effect on total lipid c ontent, although diet di d increase total li pid content for the GLM and LON in cull cows after 84 days of concentrate feeding. There being no difference in intramuscular fatty acid content in the LOD was surprising since this muscle had shown an increase in marbling and size (c hapter 5) which should logically result in an increase in both neutral and phospholipid c ontent. Elmore et al. (2004) and Nuernberg et al. (2005) both reporte d that diet effect longissimus muscle fatty acid profiles when steers were fed either a grass based diet or a concentrate based diet. There were no discernable trends evident for the effect of days on concentrate diet or muscle on total lipid content (mg/100g) or total saturated fatty acid (SFA) cont ent (mg/100g). The interactions present showed that different mu scles have different le vels of SFA and may react differently to diet. Monounsaturated fatty acid (MUFA) content (mg/100g) was higher (P < 0.05) in steaks from cull cows fed for 84 days than those fed for 0 or 42 days. The increased MUFA is primarily attributed to the effects of prolonged concentrate feeding. Only oleic acid (C18:1), which was present in large amounts, showed any variation due to muscle or th e interaction of tr eatment x muscle. The combination of

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150 SFA C16:0 and C18:0 with the MUFA C18: 1 constituted between 81 and 84% of total lipids found in the muscles of all treatments . These findings are consistent with the reviews conducted by Wood et al. (2003) and Valsta et al. (2005). There was no significant change in the polyunsaturated fatty acid (PUFA) content as days on feed increased, nor was there an alteration (P > 0.05) in total omega content (mg/100g). Omega-3 content was highest (P < 0.05) in steaks from cull cows that did not receive concentrate feed prior to sla ughter and lowest (P < 0.05) in steaks from cull cows that were on feed for 84 days. The omega-6/omeg a-3 ratio did increase (P < 0.05) as time on feed increased. However, all levels in the present study were of an acceptable level (less than 4.65) and lower at 84 days on concentrat e than reported by others after concentrate feeding steers (Elmore et al., 2004; Nu ernberg et al., 2005; 8.5 and 9.3, 6.49 and 8.34, respectively). Saturated fatty acids as a percent of tota l fatty acids were not affected by days on feed, however the LON was lower (P < 0.05) in percent SFA than the GLM or LOD. Cifuni et al. (2004) also reported that muscles differe d in SFA content with the m. Longissimus dorsi having more SFA than the m. Semimembranosus or m. Semitendinosus in young bulls and Purchas et al. (2005) also reported that the longissimus was higher in SFA than the Triceps brachii -long head which was higher in PUFA than the longissimus muscle from A-maturity heifers. MUFA te nded to increase (P < 0.05) and PUFA tended to decrease (P < 0.05) as a per cent of lipid as time on feed increased to 84 days. The decrease in PUFA is due to a decrease in both omega-3 and omega-6 fatty acids and the increase in MUFA, particularly C16:1 (palmito leic) and C18:1 (oleic). Treatment did not (P > 0.05) effect the ratio of MUFA/SFA, but as time on feed increased the ratio of

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151 PUFA/SFA decreased la rgely due to a decrease in C20:3 (eicosatrienoic), C20:4 (arachidonic), C18:3 (linolenic ), C20:5 (ecosapentaenoic) an d C22:5 (docosapentaenoic). Also, the ratio of omega-6/omega-3 increased in meat from cull cows that were either not fed concentrate prior to slaughter or were fed a concentrate diet for 84 days. Although, conjugated linoleic acid cis -9, trans -11 (CLA) did not differ (P > 0.05) in fatty acid content (mg/100g) it did decrease (P < 0.05) as a percent of total fatty acid after cull cows were on a concentrate diet for 84 days. Ba ublits et al. (2006) al so reported that supplementation with soyhulls when cattle are on fescue or orchardgrass pasture did not impact (P > 0.05) CLA content in the longissimus muscle. These results were surprising since beef from an extensive pasture based system have been shown to have more CLA than beef from cattle raised in an intensive system (Reas et al., 2003). Although diet does seem to impact on fatty acid profiles in beef animals, due to rumen biohydrogenation, genetics (Raes et al., 2001), breed (Raes et al., 2003; Nuernberg et al., 2005), specie (Patkowska-Sokola et al., 2002), and muscle t ype (Raes et al., 2003; Purchas et al., 2005) may be of greater influence when cull cows were fed for a short duration, such as the present study. Relationship of Fatty Acids and Sensory Off-flavor Principal components analysis (PCA) was utilized as a data reduction tool to investigate which fatty acids could have been associated with treatments having more offflavor. Principal components are presented in Table 6-5. The first principal component loading (PC 1) accounted for approximately 95% of the total varian ce (0.73) found in the samples, while the next largest percentage accounted for was 3% in PC2. The reported Eigen values were low for all of the princi ple components (less th an one) which can be explained by low correlations between variables in the dataset. Due to low correlation

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152 coefficients regression analysis was performed on all of the fatty acids and ratio variables with off-flavor as the dependant variable and fatty acid as the independent variable. Through regression analysis it was found that none of the fatty acid variables had a relationship to off-flavor score (P > 0.08, R2 < 0.10). This can be visually explained by Figure 6-1 which is a plot of the linear comb inations of fatty acids. The plot of the principal components of fatty acid compos ition shows that there was no detectable separation between fatty acid profiles as the three treatments are centered closely to one another. As well, when regression analys is was performed on th e ratio variables of PUFA:SFA, MUFA:SFA, UNS:SFA and n-6: n-3 no relationship was found (P > 0.35, R2 < 0.01) between ratio and sensory off-flavor scores. As time on feed increased, the flavor de scriptor of “other” was more commonly characterized as tallowy or beef y. These two flavor attributes have been associated with the oxidation products of C18:2 (2-octenal and 2, 4-decadienal) which has been shown to increase in beef with concentrate feeding (Reas et al., 2003; Elmore et al., 2004; Purchas et al., 2005). Although C18:2 did not change with increased feeding, its relative proportion to C18:3 did increase with time on feed which could explain the transition from grassy to tallowy off-flavors. It has been reported that PUFA are responsible for off-flavor notes in red meat due to lipid oxidation and generation of free radicals (Vatansever et al., 2000) in these fatty acids which can lead to the production of aldehydes, alcohols, and ketone s (Larick et al., 1987; Larick and Turner, 1990a; Elmore et al., 1999). In a review, Wood et al., (2003) concluded that detrimen tal effects to meat flavor occur when C18:3 levels are approxi mately 3% of the ne utral and phospholipid fractions. Linolenic acid (C18:3 n-3) is typica lly higher in grass fed beef due to its large

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153 presence in forages (Melton et al.,, 1982; R eas et al., 2003) leading to a grassy flavor characteristic. Although grassy flavors were the second largest off-flavor noted for cull cows fed for 0 days, the combined neutral and phospholipid percen t of C18:3 was less than 1% in the present study. The low leve ls of 18:3 n-3 may partially explain the differences between the current study and the findings of Larick and Turner (1990b) who found that total phospholipid and certain fatty acids in phospholipids were significantly correlated with differences in flavor characte ristics of ground beef. It was reported that mostly SFA and MUFA were responsible fo r cooked beef fat flavors, while the phosphatydl portion of phospholipids, especially phosphatidylcholine and lysophosphatidylethanolamine, were highly corre lated to flavors char acterized as sour and bloodlike. No fatty acids or phospholip ids were found to be highly correlated to gamey tastes, and grassy characteristics were not discussed. It has been hypothesized that fatty acid ratio balance may be a greater determining factor in flavor production than individual fatty acids (Farmer, 1994). For th is reason regression an alysis was performed looking at the ratios of MUFA/SFA, PUFA /SFA, UNS/SFA, and omega-6/omega-3 to sensory off-flavor scores. It was found that fatty acid ratios did not affect (P > 0.10, R2 < 0.05) sensory off-flavor score for steaks from cull cows that were slaughtered either directly off pasture or were realim ented for a short period. Implications Short-term realimentation decreased sens ory off-flavor detection after 42 days on feed. Realimentation also decreased the per centage of samples that were found to posses off-flavors. Even though fatty acids ar e known precursors to off-flavor compounds it does not appear that fatty acid composition di rectly effected offflavor production or detection in cull cows that were realimented for a short time prior to slaughter. When

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154 examining factors that impact o ff-flavor production it may be mo re beneficial to look at the total number of samples that were detected with off-flavors rather than the sensory off-flavor score, due to the dilution that ma y occur to the sensory off-flavor score by the samples that were rated as not having off-fl avors. In the presen t study, it is difficult to discern if improvements in off-flavor scor e were due to alterations in precursory compounds or due to less total samples being de tected with off-flavors. It would appear that due to no significant findings of the effects of fatty acids on off-flavor that the latter would prevail. More research is warranted examining the effects of supplemental feeding of cull cows prior to slaughter on fatty aci d composition and how fatty acids react with other compounds on off-flavor production. A greater understanding of how feeding impacts flavor production would aid in further processing value based decisions including use of marinades and how products fr om cull cow muscles should be marketed.

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155 Table 6-1. Main effect of days on concentr ate feed on least squares means for sensory off-flavor score and Chi-square1 frequency2 distribution of off-flavor descriptors for meat from cull cows Treatment3 Trait 0 Days 42 Days 84 Days SEM Off-flavor4 5.10b 5.45a 5.49a 0.05 Descriptors Metallic 38 26 31 --Grassy 87 77 51 --Livery 36 17 38 --Grainy 8 2 5 --Gamey 108 54 43 --Other5 24 20 22 --No off-flavor 297 402 408 --% Off-flavor 50.3 32.8 31.8 --1Chi-square is signif icant at P < 0.01 for treatment effects. 2There were 598 observations for each treatment. 30, 42, and 84 = days cull cows spent on concentrate diet. 41 = extreme off-flavor, 2 = strong off-flavor , 3 = moderate off-flavor, 4 = slight offflavor, 5 = threshold off-flavor and 6 = No off-flavor detected. 5Most common descriptors associated with other were fishy, fatty, or tallowy. abLeast squares means in the same row having di fferent superscripts are significant at P < 0.05.

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156 Table 6-2. Main effect of musc le on least squares means for sensory off-flavor score and Chi-square1 frequency2 distribution of off-flavor descriptors for muscles from cull cows Muscle3 Trait GLM LOD LON REF SEM Off-flavor4 5.33ab 5.24b 5.48a 5.33ab 0.05 Descriptors Metallic 18 40 11 26 --Grassy 47 55 62 51 --Livery 31 19 22 19 --Grainy 3 3 4 5 --Gamey 63 61 44 37 --Other5 25 17 11 13 --No off-flavor 261 253 294 297 --% Off-flavor 41.7 43.5 34.4 33.7 --1Chi-square is signif icant at P < 0.01 for muscle effects. 2There were 448 observations for each muscle. 3GLM = m. Gluteus medius , LOD = m. Longissimus dorsi , LON = m. Triceps brachii – long head, and REF = m. Rectus femoris . 41 = very strong off-flavor, 2 = strong off-flavor, 3 = moderate off-flavor, 4 = slight offflavor, 5 = threshold off-flavor and 6 = no off-flavor detected. 5Most common descriptors associated with other were fishy, fatty, or tallowy. abLeast squares means in the same row having di fferent superscripts are significant at P < 0.05.

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157Table 6-3. Least squares means for percent of total fatty acid (FA), concentration (mg/ 100g of meat), and ratios of saturated ( SFA), monounsaturated (MUFA), and polyunsatur ated (PUFA) fatty acids for the m. Gluteus medius (GLM), m. Longissimus dorsi (LOD), and m. Triceps brachiilong head (LON) for cull cows by days on concentrate feed Treatment 0 Days 42 Days 84 Days Trait GLM LOD LON GLM LOD LON GLM LOD LON SEM Effect1 mg/100g meat Total lipid 2783.33 3350.00 2783.334600.004100.003050.00 5333.333466.673933.33509.35M, T*M SFA 1356.67 1682.50 1306.672301.252009.581409.17 2546.251645.001863.75259.38M, T*M MUFA 1059.17 1342.08 1107.081787.081754.581328.75 2296.671561.251725.42207.42T, T*M PUFA 128.75 175.00 180.83 170.83 145.42 166.25 153.33 95.00 126.67 20.87 NS n-6 88.33 131.67 125.83 122.08 112.92 127.50 116.67 77.92 102.08 16.73 NS n-3 40.42 43.33 57.08 51.67 33.75 39.17 37.08 17.08 26.67 6.58 T Unknown 240.00 151.67 187.92 339.58 189.17 147.50 337.92 166.25 216.25 43.04 M % of total FA SFA 48.80 49.68 46.04 49.34 48.73 46.37 47.64 47.41 47.03 1.11 M MUFA 38.04 40.55 40.65 39.30 42.81 43.30 43.22 45.04 44.05 1.10 T, M PUFA 5.27 5.05 6.78 4.44 3.95 5.60 2.99 2.77 3.44 0.56 T, M n-6 3.75 3.69 4.71 3.30 3.10 4.36 2.29 2.29 2.81 0.50 T, M n-3 1.55 1.36 2.13 1.20 0.91 1.29 0.70 0.47 0.63 0.15 T, M Ratios MUFA/SFA 0.78 0.82 0.91 0.80 0.88 0.94 0.91 0.95 0.95 0.04 M PUFA/SFA 0.11 0.10 0.15 0.09 0.08 0.12 0.06 0.06 0.07 0.01 T, M UNS/SFA2 0.89 0.92 1.06 0.89 0.96 1.06 0.98 1.01 1.02 0.05 M n-6/n-3 2.47 2.66 2.40 2.67 3.05 3.84 3.11 4.37 4.64 0.53 T 1Effects are shown at P < 0.05; T = Treatment of days on feed, M = Muscle, T*M = Interaction of treatmen t by muscle, and NS = No t significant. 2UNS = Unsaturated fatty acids (MUFA + PUFA).

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158Table 6-4. Least squares means for concentration (mg/100g of meat) of saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids for the m. Gluteus medius (GLM), m. Longissimus dorsi (LOD), and m. Triceps brachiilong head (LON) for cull cows by days on concentrate feed Treatment 0 Days 42Days 84 Days Trait GLM LOD LON GLM LOD LON GLM LOD LON SEM Effect1 SFA C14:0 65.42 93.75 70.42 118.75 118.33 84.17 150.00 107.92 128.33 16.34 T, T*M C16:0 796.25 1030.00 784.171287.921260.83860.83 1506.25 1036.251143.33150.42M, T*M C18:0 495.00 557.92 451.67895.42 632.08 461.67 889.17 500.42 590.00 97.51 M, T*M MUFA C14:1 15.42 12.08 12.92 26.67 25.00 18.33 25.83 20.42 20.00 4.02 T C16:1 102.08 121.67 107.50155.00 162.92 137.50 212.92 159.58 188.75 20.23 T C18:1 941.67 1208.33 985.421605.831566.251170.832057.50 1380.831518.33186.30T, M, T*M PUFA C18:2 n-6 70.00 95.42 93.33 105.83 89.17 97.50 107.92 66.67 90.00 13.09 NS C20:3 n-6 0.42 0.00 1.67 1.67 1.25 1.25 0.00 0.00 0.00 0.71 NS C20:4 n-6 17.92 35.42 32.08 14.58 22.50 29.17 7.50 9.17 12.92 5.32 T, M C18:3 n-3 17.50 22.92 23.33 16.67 12.92 18.33 7.08 7.50 11.67 2.78 T C20:5 n-3 0.42 0.83 0.50 0.42 0.83 0.42 0.00 0.00 0.00 0.81 T C22:5 n-3 3.33 5.42 10.42 3.33 1.25 5.00 0.00 0.00 0.00 1.64 T, M CLA cis 9, trans 11 18.75 14.17 16.67 30.00 18.75 15.42 30.00 9.58 15.42 3.91 M 1Effects are shown at P < 0.05; T = Treatment of days on feed, M = Muscle, T*M = Interaction of treatmen t by muscle, and NS = No t significant.

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159 Table 6-5. Principal component s analysis (PCA) for partitio ning of fatty acid variance (mg/100g) for cull cows fed concentrate diets for differing periods of time Principle Component Eigen Vectors Fatty acids PC 1 PC 2 PC 3 C14:0 0.051 0.039 -0.110 C14:1 0.012 0.010 -0.013 C16:0 0.558 0.542 -0.602 C16:1 0.068 -0.057 -0.179 C18:0 0.352 0.523 0.759 C18:1 0.746 -0.652 0.117 C18:2 n-6 0.031 0.039 -0.036 C18:3 n-3 0.001 0.010 0.018 CLA, c 9, t 11 0.010 0.010 0.033 C20:3 n-6 -0.001 -0.001 0.000 C20:4 n-6 0.001 0.022 0.023 C20:5 n-3 0.00 -0.001 0.000 C22:5 n-3 -0.002 -0.002 -0.003 Eigen values Eigen value 0.691 0.024 0.009 Proportionate value 0.949 0.033 0.013 Cumulative value 0.949 0.982 0.995

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160 -2 -1 0 1 2 3 -0.6-0.5-0.4-0.3-0.2-0.10.00.10.20.30.40.50.6 Figure 6-1. Principal components pl ot for fatty acid analysis. PC1 PC 2 + 0 Days 42 Days 84 Days

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161 CHAPTER 7 OVERALL CONCLUSIONS AND IMPLICATIONS Cull cows commercially identified as fed or not-fed were not similar to USDA Select A-maturity carcasses in there car cass quality. However, cull beef cows commercially identified as fed were superior to commercially identified non-fed cull beef cows for their carcass characte ristics including larger ribe ye area, more marbling, more youthful lean maturity and improvements in lean and fat subjective color scores. Similarly, dairy type cows commercially identified as fed had more marbling and a numerically more youthful lean maturity whic h lead to an improvement in quality grade when compared to commercially identified nonfed dairy cows. Comm ercially identified fed dairy cows also had whiter fat and incr eased hot carcass weight s and larger ribeye areas than dairy cows that were commercially identified as non-fed. Select, A-maturity steer carcasses had lower Warner-Bratzler shear force values, increased sensory tenderness ratings, less dete ctable off-flavors and fewer samples with off-flavors that any of the four commercially identified cull cow groups. With that being stated, the group commercially identified as beef not-fed had the highest shear force values, lowest sensory tenderness ratings, the strongest detectable off-flavors and most samples in which off-flavors were present. Cull cow carcasses commercially identified as beef fed, dairy not-fed and dairy fed were all similar in shear force values, sensory tenderness ratings, detectable off-flavors a nd number of samples with detectable offflavors, and categorically were between th e Select, A-maturity group and the cull cow beef not-fed group. One of the main objectives of this research was to compare muscles

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162 of the round and chuck to those of the m. Longissimus dorsi . It was found that in all groups examined, the eight excised muscles besides the longissimus were similar to, or more tender than the longissimus for both shear force and sensory tenderness. It is beneficial for processors to segr egate cull cows into distinct groups prior slaughter based upon whether or not they are perceived to have been fed or not. The commercially identified fed cull cows of bot h types exhibited more desirable carcass characteristics and carcass quality than did the commercially identified non-fed cull cow groups. As well, the current research has shown that there are several muscles in commercially identified fed cull cow carcasses th at are similar to or more tender than the longissimus muscle which could be of benefit to the industry through increased use in value-added product lines to meet the demand for beef as an intermediately priced, competitive protein source. Cull beef cows that were fed a known c oncentrate diet for 84 days prior to slaughter exhibited increased live weight , body condition score and average daily gains when compared to cull cows that were not fed or were fed for only 42 days. As well, carcasses from cull cows that rece ived a concentrate diet prio r to slaughter had increased hot carcass weights, ribeye ar ea, fat over the eye at the 12th rib and marbling score when compared to cull cows that were not fed. In addition, cull cows fed for 84 days had brighter cherry red lean colo r, whiter carcass fat, firmer lean and a heavier muscled carcass than cull cows that were not fed. Cull cows that were fed a concentrate diet for 42 days were intermediate to the cows that we re not fed and the cows that were fed for 84 days for almost all carcass traits.

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163 After cull cows were on a concentrate diet for 84 days the LON and LOD had a higher percent and content of soluble collage n with no changes occurring in the total collagen content. After cows were realimented for 84 days, two of the nine muscles evaluated became significantly more tender ( m. Gluteus medius and m. Longissimus dorsi ) than those from cull cows that did not receive any concentrate or cull cows that received a concentrate diet for 42 days. Six of the remaining muscles did not change in shear force tenderness rating, wh ile one, become less tender ( m. Vastus lateralis ). However, after 84 days of concentrate feedi ng 6 muscles were similar to or more tender than the longissimus muscle making them acceptable candidates for increased use in value added items. Trained sensory panelists also rated steaks from cull cows that were realimented for 84 days as more tender and havi ng less detectable off-flavors than steaks from cull cows that were not realimented or realimented for only 42 days. As well, the number of samples with detectable off-flavor decreased dramatically after cull cows were realimented for 42 days with the largest decr eases occurring in gamey and grassy tasting off-flavors. It was also found that it may be beneficial to age muscles from cull cows for 20 days postmortem to take full advantage of the benefits of postmortem tenderization without the detriment of incr eased off-flavor production. Although treatment or group in the two studies did impact some fatty acids, muscle, breed and genetics may play a more important determining role in fatty acid composition of meat from ruminants than did diet. In the current studi es fatty acid composition of the lean tissue or of the lipid fraction was not re lated to the incidence of sensory off-flavor detection.

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164 From the current research it is beneficial to commercially identify cull cows as fed or not-fed prior slaughter due to the increas ed value that may be attained from there carcasses and muscles. It may also be benefi cial for producers to feed their cull cows for a short time of up to 84 days before they ar e sent to slaughter or sold. However, producers should use caution and perform an economical analysis based upon cost of inputs including medicines and feed, current market conditions and market outlook conditions for two to three months after the st art of feeding. If cu ll cows are realimented it may be possible for both producers and pr ocessors to capitalize on the increased condition and value of cull cow meat to meet the increasing demand of intermediately priced beef options. However, more research is warranted ex amining the economic conditions that may impact the profitability of feeding cull cows including addition of repartitioning agents to increase the lean to fat ratios. More research is also warranted to examine the effects of postmortem tenderization treatments including marination ingredients that may further increase the tenderness and acceptability of cull cow meat. It has been well established that breakdown products of fatty acids are part ially responsible for (off-) flavor formation in beef. Although fatty acids in the current st udies were not related to sensory off-flavor detection, it is of value to further investig ate how diets fed to cull cows impact (off-) flavor production in the meat and complexes formed during thermal degradation that may be altered by addition of marinades.

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165 APPENDIX A BENCHMARKING THAW AND COOK LOSSES OF SELECTED MUSCLES FROM COMMERCIALLY IDENTIFIED FED AN D NON-FED BEEF AND DAIRY CULL COWS AND USDA SELECT A-MATURITY FED STEERS Data for thaw and cook losses were collect ed from steaks utilized for WarnerBratzler shear force testing. Methodology of thawing and cooking can be found in the materials and methods section of chapter 3 under Warner-Bratzle r shear force. Statistical analysis was performed as a split-plot desi gn by the same methods described in chapter 3 materials and methods – statistical analysis . Interactions were observed between and group and muscle and were therefore explored.

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166 Table A-1. Least squares means for the main effect of group on percent thaw and cook loss Group1 Trait B-NF B-F D-NF D-F SEL SEM Thaw loss, % 5.68a 5.67a 4.97ab 4.76b 5.51a 0.26 Cook loss, % 29.36 29.19 29.29 28.95 28.98 0.39 1B-NF = Beef Not-Fed, B-F = Beef Fed, D-NF = Dairy Not-Fed, D-F = Dairy Fed, SEL = USDA Select. abLeast squares means in the same row having di fferent superscripts are significant at P < 0.05.

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167Table A-2. Least squares means for the main ef fect of muscle on percent thaw and cook loss Muscle1 Trait GLM INF LAT LOD LON PSO REF TEM TFL SEM Thaw loss, % 6.60ab 4.58de 4.06e 6.76a 6.13bc 4.64de 5.75c 4.70d 4.63de 0.24 Cook loss, % 29.48b 32.81a 23.59d 25.15c 29.20b 32.20a 31.58a 29.35b 29.03b 0.47 1GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae . abcdeLeast squares means in the same row having the di fferent superscripts are significant at P < 0.05.

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168 Table A-3. Least squares means1 for percent thaw loss inte raction of group by muscle Group2 Muscle3 B-NF B-F D-NF D-F SEL GLM 7.22a,vw 6.47a,x 6.54a,v 6.21a,w 6.57a,wx INF 4.30b,yz 3.93b,z 3.95b,xyz 4.30b,xy 6.41a,wx LAT 3.68bc,z 4.71ab,yz 3.37bc,yz 2.95c,z 5.61a,wxy LOD 7.94a,v 6.45b,x 6.47ab,v 6.03b,w 6.91ab,w LON 6.72a,vw 6.56a,x 5.68a,vw 5.47a,wxy 6.22a,wx PSO 5.89a,wx 5.61a,xy 4.81a,wx 4.89a,wxy 2.01b,z REF 5.91a,wx 5.97a,xy 5.91a,vw 5.55a,wx 5.40a,xy TEM 5.09a,xy 5.23a,xyz 4.71a,wxy 3.86a,yz 4.61a,y TFL 4.38b,yz 6.07a,xy 3.29b,z 3.56b,yz 5.86a,wxy 1Standard error of least square s means for interactions = 0.54. 2B-NF = Beef Not-Fed, B-F = Beef Fed, D-NF = Dairy Not-Fed, D-F = Dairy Fed, SEL = USDA Select. 3GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae . abcLeast squares means in the same row having di fferent superscripts are significant at P < 0.05. vwxyzLeast squares means in the same column ha ving different superscr ipts are significant at P < 0.05.

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169 Table A-4. Least squares means1 for percent cook loss inte raction of group by muscle Group2 Muscle3 B-NF B-F D-NF D-F SEL GLM 28.75a,xy 30.54a,wx 30.82a,vwx 28.80a,y 28.51a,y INF 31.91bc,vw 33.64ab,v 32.04bc,v 36.18a,w 30.27c,y LAT 24.12a,z 23.01a,z 24.12a,z 23.49a,z 23.21a,z LOD 26.00ab,yz 25.93ab,yz 26.33a,yz 23.16b,z 24.34ab,z LON 29.48a,wx 28.55a,xy 28.69a,wxy 29.26a,xy 30.00a,y PSO 33.08a,v 31.56ab,vw 32.33ab,v 29.77b,xy 34.24a,x REF 31.23ab,vwx 30.26b,wx 31.36ab,vw 31.68ab,x 33.37a,x TEM 30.29a,vwx 29.87a,wx 28.43a,xy 29.43a,xy 28.70a,y TFL 29.37a,wx 29.36a,wx 29.48a,vwx 28.79a,y 28.14a,y 1Standard error of least square s means for interactions = 1.05. 2B-NF = Beef Not-Fed, B-F = Beef Fed, D-NF = Dairy Not-Fed, D-F = Dairy Fed, SEL = USDA Select. 3GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae . abcdLeast squares means in the same row having different superscripts are significant at P < 0.05. vwxyzLeast squares means in the same column ha ving different superscr ipts are significant at P < 0.05.

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170 APPENDIX B BENCHMARKING DEMENSIONS AND WE IGHTS OF SELECTED MUSCLES FROM COMMERCIALLY IDENTIFIED FE D AND NON-FED BEEF AND DAIRY CULL COWS AND USDA SELECT A-MATURITY FED STEERS Carcass selection is outlined in the ma terials and methods of chapter 3 under carcass selection. At Packerland Packing (G reenbay, Wisconsin) prior to packaging, muscles were trimmed to a commercial fa t thickness of 0.64 cm and weights were recorded. Muscles were then trimmed of all visible fat cover (0.0 cm) and denuded of any visible connective tissues. The m. Triceps brachii was separated into the lateral and long heads at this point. Denuded weights we re taken, as well as, muscle length, muscle width, minimum muscle depth and maximum muscle depth. Least squares means, Mixed procedures of Statistical Analysis System V. 9.1 (SAS Inst. Inc, 2005) were used to test the split -plot design where carca ss was the whole-plot and muscle was the split-plot as described in chapter 3 materials and methods – statistical analysis.

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171 Table B-1. Main effect of group1 on least squares means for muscle2 dimensions3 Group Muscle B-NF B-F D-NF D-F SEL SEM P > F4 GLM MinD 3.13bc 3.47b 2.32c 3.27b 4.33a 0.28 *** MaxD 8.23bc 9.70a 7.29c 9.63ab 10.15a 0.50 *** Length 27.03a 25.57a 23.64b 27.93ab 24.93ab 0.91 ** Width 24.10 23.27 21.36 23.47 22.07 0.94 ns INF MinD 2.23a 1.50b 1.39b 2.13a 1.70ab 0.21 * MaxD 6.13b 6.13b 4.75a 6.37b 5.96b 0.30 ** Length 40.20b 40.00bc 37.07bc 44.40a 36.10c 1.40 *** Width 14.07 13.87 12.86 14.07 13.33 0.55 ns LAT MinD 1.73 1.67 1.57 1.73 1.62 0.21 ns MaxD 4.80 5.30 4.32 5.07 4.91 0.29 ns Length 29.83 27.97 28.89 28.70 25.93 1.49 ns Width 14.07ab 13.30b 12.23b 15.20a 13.71ab 0.66 * LOD MinD 2.83 2.60 1.76 2.50 3.13 0.46 ns MaxD 5.20bc 5.97ab 4.43c 5.97ab 6.57a 0.29 *** Length 44.90a 45.47a 38.26b 47.13a 39.73b 1.66 *** Width 19.73a 18.40a 16.00b 20.13a 18.13ab 0.80 ** LON MinD 1.23ab 1.40ab 1.02b 1.70a 1.73a 0.18 * MaxD 5.00ab 5.17ab 4.52b 5.77a 5.47a 0.29 * Length 31.90ab 34.73a 31.58ab 35.53a 30.53b 1.36 * Width 16.17 15.80 14.51 16.40 15.20 0.69 ns PSO MinD 1.10 1.37 1.11 1.31 1.57 0.23 ns MaxD 5.57bc 5.93ab 5.01c 5.43bc 6.67a 0.30 ** Length 65.47b 62.20bc 59.25bc 71.93a 57.07c 2.14 *** Width 13.93 14.13 12.43 13.20 12.87 0.67 ns REF MinD 2.73 3.13 2.54 3.20 5.33 1.05 ns MaxD 7.27ab 7.57a 6.32b 8.10a 7.70a 0.38 * Length 27.93 27.80 25.96 28.90 27.27 1.13 ns Width 12.43 13.47 11.11 13.43 12.70 0.63 ns TEM MinD 0.97 1.07 1.02 1.23 0.97 0.18 ns MaxD 2.83ab 2.97a 2.34b 3.10a 3.25a 0.17 ** Length 29.63 29.00 28.89 31.17 27.13 1.19 ns Width 6.87 8.20 6.21 8.00 7.13 0.57 ns TFL MinD 1.30b 1.73ab 1.67ab 2.23a 2.13a 0.24 *

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172 MaxD 4.00 4.40 3.80 4.37 4.50 0.32 ns Length 31.73 31.57 29.00 33.13 31.47 1.30 ns Width 16.33a 15.30a 12.75b 17.10a 16.33a 1.06 ** 1B-NF = Beef Not-Fed, B-F = Beef Fed, D-NF = Dairy Not-Fed, D-F = Dairy Fed, SEL = USDA Select. 2GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae . 3MinD = Minimum depth, MaxD = Maximum de pth. All measurements are reported in cm. 4P < 0.05 = *, P < 0.01 = **, P < 0.001 = ***, ns = not significant (P > 0.05). abcLeast squares means in the same row having th e different superscripts are significant at P < 0.05.

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173 Table B-2. Main effect of group1 on least squares means for muscle2 weights3 Group Muscle B-NF B-F D-NF D-F SEL SEM P > F4 GLM Com Wt 3.79 3.86 3.89 3.40 3.01 0.27 ns Nud Wt 3.02 2.76 3.12 2.71 2.55 0.22 ns ComHcw 1.22a 1.00bc 1.06ab 0.79d 0.83cd 0.07 *** NudHcw 0.96a 0.71bc 0.86ab 0.63c 0.70bc 0.06 *** INF Com Wt 2.47a 2.35a 2.65a 2.18ab 1.72b 0.16 ** Nud Wt 1.80ab 1.67bc 2.08a 1.64bc 1.33c 0.12 *** ComHcw 0.80a 0.61bc 0.72ab 0.50cd 0.47d 0.04 *** NudHcw 0.59a 0.43b 0.57a 0.38b 0.37b 0.03 *** LAT5 Com Wt 3.09 3.27 3.67 2.98 2.57 0.26 ns Nud Wt 0.85b 0.85b 1.07a 0.77b 0.71b 0.07 ** ComHcw 0.99a 0.84ab 1.00a 0.68b 0.71b 0.06 *** NudHcw 0.27a 0.22b 0.29a 0.18b 0.20b 0.02 *** LOD Com Wt 4.21 5.04 4.42 3.97 3.73 0.47 ns Nud Wt 2.72 2.63 2.62 2.22 2.49 0.18 ns ComHcw 1.36a 1.29a 1.21ab 0.91c 1.03bc 0.08 *** NudHcw 0.87a 0.68b 0.72b 0.51c 0.69b 0.05 *** LON5 Com Wt 3.09 3.27 3.67 2.98 2.57 0.36 ns Nud Wt 1.20b 1.14b 1.62a 1.35ab 1.11b 0.12 * ComHcw 0.99a 0.84ab 1.00a 0.68b 0.71b 0.06 *** NudHcw 0.38ab 0.29c 0.44a 0.31bc 0.31bc 0.03 ** PSO Com Wt 2.77ab 2.65ab 3.13a 2.53b 2.27b 0.19 * Nud Wt 1.90ab 1.84abc 2.15a 1.75bc 1.50c 0.13 ** ComHcw 0.89a 0.69b 0.86a 0.59b 0.63b 0.05 *** NudHcw 0.61a 0.48b 0.59a 0.40b 0.41b 0.03 *** REF Com Wt 1.74a 1.70ab 1.90a 1.66ab 1.38b 0.12 * Nud Wt 1.49 1.42 1.58 1.42 1.20 0.10 ns ComHcw 0.56a 0.44bc 0.52ab 0.39c 0.38c 0.03 *** NudHcw 0.48a 0.37bc 0.43ab 0.33c 0.33c 0.03 *** TEM Com Wt 0.42 0.37 0.47 0.53 0.35 0.09 ns Nud Wt 0.28 0.30 0.36 0.27 0.27 0.02 ns ComHcw 0.13 0.10 0.13 0.12 0.10 0.02 ns NudHcw 0.09a 0.08b 0.09a 0.06b 0.08b 0.01 ** TFL Com Wt 1.21a 1.22a 1.33a 1.21a 0.92b 0.10 * Nud Wt 0.89 0.91 0.92 0.84 0.70 0.08 ns

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174 ComHcw 0.39a 0.32bc 0.36ab 0.28c 0.25c 0.02 *** NudHcw 0.29a 0.24ab 0.25ab 0.19b 0.19b 0.24 ** 1B-NF = Beef Not-Fed, B-F = Beef Fed, D-NF = Dairy Not-Fed, D-F = Dairy Fed, SEL = USDA Select. 2GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TEM = Teres major , TFL = Tensor fasciae latae . 3Com = Commercial weight ta ken at 0.64 cm fat thickness in kg, Nud = denuded weight taken at 0.0 cm fat thickness in kg, ComHcw = Commercial weight as a percent of hot carcass weight, NudHcw = denuded weight at a percent of hot carcass weight. 4P < 0.05 = *, P < 0.01 = **, P < 0.001 = ***, ns = not significant (P > 0.05). 5Commercial weight was taken as whole m. Triceps brachii , denuded weight is taken after muscle separation into lateral and long heads. abcdLeast squares means in the same row having the different superscr ipts are significant at P < 0.05.

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175 Table B-3. Least squares means of pooled commercial and denuded muscle weights as a percent of hot carcass weight for main effect of group1 Group Trait2 B-NF B-F D-NF D-F SEL SEM ComHcw 6.52a 5.47bc 5.93ab 4.50c 4.55c 0.35 NudHcw 4.67a 3.61b 4.37a 3.17b 3.38b 0.24 1B-NF = Beef Not-Fed, B-F = Beef Fed, D-NF = Dairy Not-Fed, D-F = Dairy Fed, SEL = USDA Select. 2ComHcw = Commercial trim muscle weight at 0.64 cm fat thickness as a percent of hot carcass weight, NudHcw = Denuded trim muscle weight at 0.0 cm fat thickness as a percent of hot carcass weight. abcLeast squares means in the same row having th e different superscripts are significant at P < 0.05.

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176 APPENDIX C THAW AND COOK LOSSES OF SELECTED MUSCLES FROM CULL BEEF COWS FED A CONCENTRATE DIET FOR 0, 42 AND 84 DAYS Data for thaw and cook losses were collect ed from steaks utilized for WarnerBratzler shear force testing. Methodology of thawing and cooking can be found in the materials and methods section of chapter 5 under Warner-Bratzle r shear force. Statistical analysis was performed as a split-plot desi gn with carcass as the w hole-plot and muscle as the sub-plot as described in chapter 5 ma terials and methods – statistical analysis. Thaw loss had significant (P < 0.05) main effects for muscle, however, no significance was observed for the main effects of treatment or days of aging. As well, no two way or three way interactions were significant at P < 0.05 for thaw loss. Cook loss had significant (P < 0.05) main effects for treatmen t and muscle, but days of age did not have a significant effect. As well, the interac tion of treatment by muscle was found to be significant (P < 0.05); however, no further in teractions were significant for cook loss.

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177 Table C-1. Least squares means for the main effect of treatment on percent thaw and cook loss Treatment1 Trait 0 Days 42 Days 84 Days SEM Thaw loss, % 2.71 2.83 2.15 0.20 Cook loss, % 30.73a 33.63b 30.34a 0.30 10, 42, and 84 days = the time cull cows spent on concentrate feed. abLeast squares means in the same row having di fferent superscripts are significant at P < 0.05.

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178Table C-2. Least squares means for the main ef fect of muscle on percent thaw and cook loss Muscle1 Trait GLM INF LAT LOD LON PSO REF TFL VLS SEM Thaw loss, % 4.36a 1.22e 3.20b 2.97b 2.74bc 2.09cd 1.85de 2.06cd 2.58bcd 0.30 Cook loss, % 32.22b 32.17b 32.65b 30.05c 29.89c 28.07d 31.68b 32.62b 34.76a 0.53 1GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii long head, PSO = Psoas major , REF = Rectus femoris , TFL = Tensor fasciae latae, VLS = Vastus lateralis . abcdLeast squares means in the same row having the di fferent superscripts are significant at P < 0.05.

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179 Table C-3. Least squares means1 for percent cook loss intera ction of treatment by muscle Treatment2 Muscle3 0 Days 42 Days 84 Days GLM 32.12b,xy 35.53a,y 29.01b,wxyz INF 30.89b,y 34.46a,y 31.17b,vw LAT 31.70b,xy 35.63a,y 30.62b,wxy LOD 31.40a,xy 31.47a,z 27.28b,z LON 29.77ab,y 31.43a,z 28.46b,xyz PSO 26.78a,z 29.25a,z 28.20a,yz REF 30.02b,y 31.60ab,z 33.41a,uv TFL 29.93b,y 36.93a,y 30.98b,vwx VLS 33.99ab,x 36.37a,y 33.90b,u 1Standard error of least square s means for interactions = 0.91. 20, 42, and 84 days = the time cull cows spent on concentrate feed. 3GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TFL = Tensor fasciae latae , VLS = Vastus lateralis . abLeast squares means in the same row having di fferent superscripts are significant at P < 0.05. uvwxyzLeast squares means in the same column having different superscripts are significant at P < 0.05.

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180 APPENDIX D DEMENSIONS AND WEIGHTS OF SELECTED MUSCLES FROM CULL COWS FED A CONCENTRATE DIET FOR 0, 42 AND 84 DAYS Animal, treatment, and carcass information is available in chapter 5. Muscles were trimmed to a commercial fat thickness of 0.64 cm and weights were recorded. Muscles were then trimmed of all visible fat cover ( 0.0 cm) and denuded of any visible connective tissues. The m. Triceps brachii was separated into the lateral and long heads at this point. Denuded weights were taken, as well as, musc le length, muscle width, minimum muscle depth and maximum muscle depth. Least squares means, Mixed procedures of Statistical Analysis System V. 9.1 (SAS Inst. Inc, 2005) were used to analyze the split-plot de sign where carcass was the wholeplot and muscle was the subplot as described in chapte r 5 materials and methods – statistical analysis.

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181 Table D-1. Main effect of treatment1 on least squares means for muscle2 dimensions3 Treatment Muscle 0 Days 42 Days 84 Days SEM P > F4 GLM MinD 2.88 2.69 3.00 0.20 ns MaxD 6.31 7.63 7.50 0.43 ns Length 23.56b 25.06b 27.81a 0.84 ** Width 21.50b 22.50b 24.75a 0.74 * INF MinD 1.63 1.69 1.56 0.23 ns MaxD 4.56 5.06 5.25 0.31 ns Length 33.38 35.38 37.75 1.26 ns Width 11.63 11.88 12.25 0.38 ns LAT MinD 1.44 1.94 1.38 0.17 ns MaxD 4.19 4.31 4.44 0.29 ns Length 25.88 25.75 27.00 0.76 ns Width 12.50 12.50 13.38 0.74 ns LOD MinD 2.13b 2.13b 2.81a 0.21 * MaxD 4.88 5.06 5.89 0.20 ns Length 41.38 38.38 42.13 1.35 ns Width 19.13a 16.44b 18.63a 0.69 * LON MinD 1.31 1.38 1.19 0.18 ns MaxD 4.13 4.75 4.75 0.24 ns Length 27.13b 27.25b 32.00a 1.00 ** Width 14.25 13.81 14.25 1.00 ns PSO MinD 1.44 1.25 1.31 0.18 ns MaxD 4.75 5.00 4.81 0.24 ns Length 56.38b 55.88b 63.38a 1.42 *** Width 10.75 12.25 11.25 1.02 ns REF MinD 2.75 2.69 3.19 0.35 ns MaxD 6.25 6.50 6.25 0.35 ns Length 26.25 26.38 26.81 0.83 ns Width 11.38 11.50 11.56 0.44 ns TFL MinD 1.75 2.25 2.38 0.23 ns MaxD 4.50 4.44 4.56 0.32 ns Length 29.88 28.00 29.75 1.13 ns Width 11.38 11.94 10.69 0.68 ns VLS MinD 1.63 1.94 2.00 0.16 ns MaxD 6.00 5.69 5.69 0.32 ns

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182 Length 26.75b 27.00b 29.50a 0.79 * Width 16.00 16.38 17.00 0.88 ns 10, 42, and 84 days = time cull cows spent on concentrate diet. 2GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TFL = Tensor fasciae latae , VLS = Vastus lateralis . 3MinD = Minimum depth, MaxD = Maximum de pth. All measurements are reported in cm. 4P < 0.05 = *, P < 0.01 = **, P < 0.001 = ***, ns = not significant (P > 0.05). abLeast squares means in the same row having th e different superscripts are significant at P < 0.05.

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183 Table D-2. Main effect of treatment1 on least squares means for muscle2 weights3 Treatment Muscle 0 Days 42 Days 84 Days SEM P > F4 GLM Com Wt 3.16b 3.76a 4.12a 0.18 ** Nud Wt 2.28b 2.82a 3.02a 0.13 ** ComHcw 1.40 1.45 1.34 0.04 ns NudHcw 1.00 1.09 1.00 0.03 ns INF Com Wt 1.63b 1.91ab 2.02a 0.12 * Nud Wt 1.20 1.42 1.51 0.10 ns ComHcw 0.71a 0.74a 0.65b 0.02 ** NudHcw 0.52 0.55 0.49 0.02 ns LAT5 Com Wt 2.37b 3.04a 3.59a 0.19 *** Nud Wt 0.65 0.74 0.79 0.06 ns ComHcw 1.04 1.18 1.18 0.07 ns NudHcw 0.28 0.29 0.25 0.02 ns LOD Com Wt 3.13b 3.67ab 4.28a 0.24 ** Nud Wt 2.32ab 1.99b 2.66a 0.13 ** ComHcw 1.39 1.42 1.38 0.06 ns NudHcw 1.02a 0.77ab 0.86b 0.03 *** LON5 Com Wt 2.37b 3.04a 3.59a 0.19 *** Nud Wt 0.92b 1.04b 1.33a 0.07 *** ComHcw 1.04 1.18 1.18 0.07 ns NudHcw 0.40 0.40 0.43 0.01 ns PSO Com Wt 2.32 2.35 2.77 0.14 ns Nud Wt 1.46b 1.46b 1.70a 0.07 * ComHcw 1.03a 0.91b 0.89b 0.04 * NudHcw 0.65a 0.57ab 0.55b 0.02 * REF Com Wt 1.51 1.61 1.65 0.09 ns Nud Wt 1.23 1.32 1.37 0.09 ns ComHcw 0.66a 0.63a 0.53b 0.02 *** NudHcw 0.54a 0.51a 0.44b 0.02 ** TFL Com Wt 1.03 1.21 1.15 0.06 ns Nud Wt 0.73 0.81 0.78 0.05 ns ComHcw 0.45a 0.47a 0.37b 0.01 *** NudHcw 0.32a 0.31a 0.25b 0.01 ** VLS Com Wt 1.61b 1.76ab 1.94a 0.08 * Nud Wt 1.23b 1.39b 1.64a 0.07 **

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184 ComHcw 0.71a 0.68ab 0.63b 0.02 * NudHcw 0.54 0.54 0.53 0.02 ns 10, 42, and 84 days = time cull cows spent on concentrate diet. 2GLM = Gluteus medius , INF = Infraspinatus , LAT = Triceps brachii -lateral head, LOD = Longissimus dorsi , LON = Triceps brachii -long head, PSO = Psoas major , REF = Rectus femoris , TFL = Tensor fasciae latae , VLS = Vastus lateralis . 3Com = Commercial weight ta ken at 0.64 cm fat thickness in kg, Nud = denuded weight taken at 0.0 cm fat thickness in kg, ComHcw = Commercial weight as a percent of hot carcass weight, NudHcw = denuded weight at a percent of hot carcass weight. 4P < 0.05 = *, P < 0.01 = **, P < 0.001 = ***, ns = not significant (P > 0.05). 5Commercial weight was taken as whole m. Triceps brachii , denuded weight is taken after muscle separation into lateral and long heads. abLeast squares means in the same row having th e different superscripts are significant at P < 0.05. T

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185 able D-3. Least squares means of pooled co mmercial and denuded muscle weights as a percent of hot carcass weight for main effect of treatment1 Treatment Trait2 0 Day 42 Day 84 Day SEM ComHcw 8.42 8.66 8.16 0.20 NudHcw 5.28 5.03 4.79 0.09 10, 42, and 84 days = time cull cows spent on concentrate diet. 2ComHcw = Commercial trim muscle weight at 0.64 cm fat thickness as a percent of hot carcass weight, NudHcw = Denuded trim muscle weight at 0.0 cm fat thickness as a percent of hot carcass weight.

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186 APPENDIX E COST AND PROFIT BREAKDOWN OF CONCENTRATE FEEDING OF CULL COWS FOR A SHORT DURATIO N PRIOR TO SLAUGHTER Cull cows were housed and fed at the Univ ersity of Florida Beef Teaching Unit – South for the duration of the project. Actual pr ices utilized include co st of feed, mineral, and medical (anthelmintic) and are: $1.94 pe r cow per day for feed (c/d), $0.04/c/d for mineral, and a one time expense of $5.60 for anthelmintic (Table E-3), no other medical costs were incurred throughout th e trial period. In the tabulations feed and mineral were combined expenses of $1.98/c/d. These values are assuming that each cow consumed the same amount as all the others everyday. Si nce cows were fed from an open field bunk and covered pasture mineral feeders it is not pos sible to calculate these figures to an exact amount for each cow. Certain numbers were used as assumed figur es to reflect real time current prices at the time of the trial. Assumed figures in cluding a yardage charge of $0.25/c/d and a 5% interest rate compounded every 42 days, for eas e of calculation (current savings interest rates compounded monthly varied from 1.0 to 3.75 %, obtained from Campus USA and Florida Credit Union, Gainesville, Florida), were applied to cu ll cows in order to figure possible capital gains if cull cows were sold when culled instead of fed. The yardage costs of $0.25 were taken from Sawyer et al. (2004) and were estimated as current yardage fees in the southwestern United Stat es calculated from Standardized Performance Analysis Software (University of Texas A&M, College Station). It is also assumed that if the cull cows were retained and fed on pers onal property, instead of yardage, a labor fee

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187 of $0.25/c/d would be assessed to cover time and gas usage to fill bunks and check for cow health. Groups of cull cows within a treatment period (0, 42, and 84 days, n = 8 each) were treated as a whole lot. Cost and profit estimates were calculated based upon lot averages and estimates as would be done at the point of sale. Cull cow value was assessed by estimating percent lean and weight averages that were taken 24 hours prior to slaughter with a 3% pencil shrink factored. Cull cow estimated worth was figured by the weekly average of the United State Department of Agriculture, Agricultural Marketing Services report LS145 (www.ams.usda.gov) for auction re ports out of Bartow, Florida the week the cows were slaughtered for pricing on a live weight basis and the national weekly cutter cow cutout and boxed cow beef cuts cut-out value, report xb461 (www.ams.usda.gov) for the hot carcass weight value. Although price/cwt would be expected to decrease as percen t lean decreased, hot carcass wei ght values were kept at the 90% lean basis for the practical purposes of this study as is reported by the USDA. Cows were slaughtered during the week of: 1) Treatm ent 1, 0 days on feed, the week of October 22, 2004, averaged 86% lean and had an aver age value of $44.00/cwt on a live basis or $107.18/cwt on a hot carcass weight basis, 2) Treatment 2, 42 days on feed, the week of December 3, 2004, averaged 85 % lean and had an average value of $52.00/cwt on a live basis or 110.97/cwt on a hot car cass weight basis, and 3) Treatment 3, 84 days on feed, the week of January 14, 2005, averaged 83% lean and had an average value of $57.50/cwt on a live basis or 111.87/cwt on a hot carcass weight basis.

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188 Table E-1. Calculations of estimat ed percent lean for live cows Live Slaughter Cow Guidelines fo r Estimation of Percent Lean Adapted from: United States Department of Agriculture Agricultural Marketing Service, January 2000 Preliminary Percent Lean*, For every 0.1 increase in adju sted preliminary yield grade (APYG) decrease percent lean (PL) by 1.0% Fat (in) APYG PPL Fat (in) APYG PPL Ab 0 1.8 90 0.5 3.2 76 0.0 2.0 88 0.6 3.5 73 0.1 2.2 86 0.7 3.7 71 0.2 2.5 83 0.8 4.0 68 0.3 2.7 81 0.9 4.2 66 0.4 3.0 78 1.0 4.5 63 Weight Adjustment Factors For every 25 lbs greater than 1100 lbs subtract 0.2 % (50 lbs = 0.4 %, 100 lbs = 0.8 %) For every 25 lbs less than 1100 lbs add 0.2 % (50 lbs = 0.4 %, 100 lbs = 0.8 %) Weight Adjust Weight Adjust Weight Adjust 600 + 4.0 900 + 1.6 1200 0.8 650 + 3.6 950 + 1.2 1250 1.2 700 + 3.2 1000 + 0.8 1300 1.6 750 + 2.8 1050 + 0.4 1350 2.0 800 + 2.4 1100 0.0 1400 2.4 850 + 2.0 1150 0.4 1450 2.8 Muscle Adjustment Factors For each numerical score less than 3 subtract 0.3 % For each numerical score greater than 3 add 0.3 % Score # Grade Adjust Score # Grade Adjust Thin 1 0.66 Avg + 6 + 0.99 Thin o 2 0.33 Thick 7 + 1.32 Thin + 3 0.00 Thick o 8 + 1.65 Avg 4 + 0.33 Thick + 9 + 1.98 Avg o 5 + 0.66 *All cows with APYG less than 2.0 are grades of 90 % regardless of weight or muscle Estimates of fat and muscle were taken from carcass measurements for the purpose of the current study

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189Table E-2. Rough data for cow wei ghts, percent lean and value a b c d e f g h i 1 ID Trt1 Initial (I) Wt, lbs Final (F) Wt, lbs % Lean I Value/cwt F Value/$ cwt I Value, $F Value, $ 2 9/53 0 984.55 984.55 81.88 44.00 44.00 433.20 433.20 3 0/58 0 1309.50 1309.50 89.28 44.00 44.00 576.18 576.18 4 1/74 0 921.50 921.50 82.36 44.00 44.00 405.46 405.46 5 7/10 0 882.70 882.70 86.33 44.00 44.00 388.39 388.39 6 1/154 0 970.00 970.00 87.36 44.00 44.00 426.80 426.80 7 1/17 0 1100.95 1100.95 87.61 44.00 44.00 484.42 484.42 8 1/4 0 1115.50 1115.50 88.05 44.00 44.00 490.82 490.82 9 8/194 0 1188.25 1188.25 88.64 44.00 44.00 522.83 522.83 10 9/44 42 1120.35 1168.85 81.14 44.00 52.00 492.95 607.80 11 1/49 42 915.68 970.00 85.62 44.00 52.00 402.90 504.40 12 8/79 42 925.38 968.06 85.60 44.00 52.00 407.17 503.39 13 1/10 42 935.08 929.26 86.23 44.00 52.00 411.44 483.22 14 9/10 42 1134.90 1154.30 86.29 44.00 52.00 499.36 600.24 15 7/82 42 1110.65 1270.70 80.83 44.00 52.00 488.69 660.76 16 0/10s 42 1189.22 1144.60 88.62 44.00 52.00 523.26 595.19 17 1/64 42 1037.90 1028.20 86.09 44.00 52.00 456.68 534.66 18 9/89s 84 1178.55 1328.90 85.62 44.00 57.50 518.56 764.12 19 8/69 84 1057.30 1285.25 82.00 44.00 57.50 465.21 739.02 20 0/164 84 1154.30 1275.55 85.19 44.00 57.50 507.89 733.44 21 0/162 84 857.48 1076.70 80.07 44.00 57.50 377.29 619.10 22 0/140 84 1057.30 1202.80 79.01 44.00 57.50 465.21 691.61 23 9/120 84 1081.55 1304.65 82.82 44.00 57.50 475.88 750.17 24 9/8s 84 1246.45 1513.20 83.50 44.00 57.50 548.44 870.09 25 0/59s 84 950.60 1033.05 85.18 44.00 57.50 433.20 594.00 1Treatment is equal to number of days on concentrate diet.

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190Table E-3. Rough figures fo r calculating cost inputs a b c d e f g h 1 ID Trt1 ADG, Final Feed/day, $ Medical, $ Yardage/d, $ COG2 Total Feeding cost, $ 2 9/53 0 0 0 0 0 0 0 3 0/58 0 0 0 0 0 0 0 4 1/74 0 0 0 0 0 0 0 5 7/10 0 0 0 0 0 0 0 6 1/154 0 0 0 0 0 0 0 7 1/17 0 0 0 0 0 0 0 8 1/4 0 0 0 0 0 0 0 9 8/194 0 0 0 0 0 0 0 10 9/44 42 1.19 1.98 5.60 0.25 1.99 99.26 11 1/49 42 1.33 1.98 5.60 0.25 1.77 99.26 12 8/79 42 1.05 1.98 5.60 0.25 2.26 99.26 13 1/10 42 -0.14 1.98 5.60 0.25 (0.33) 99.26 14 9/10 42 0.48 1.98 5.60 0.25 4.96 99.26 15 7/82 42 3.93 1.98 5.60 0.25 0.60 99.26 16 0/10s 42 -1.10 1.98 5.60 0.25 (2.59) 99.26 17 1/64 42 -0.24 1.98 5.60 0.25 (0.57) 99.26 18 9/89s 84 1.85 1.98 5.60 0.25 1.24 192.92 19 8/69 84 2.80 1.98 5.60 0.25 0.82 192.92 20 0/164 84 1.49 1.98 5.60 0.25 1.54 192.92 21 0/162 84 2.69 1.98 5.60 0.25 0.85 192.92 22 0/140 84 1.79 1.98 5.60 0.25 1.29 192.92 23 9/120 84 2.74 1.98 5.60 0.25 0.84 192.92 24 9/8s 84 3.27 1.98 5.60 0.25 0.70 192.92 25 0/59s 84 1.01 1.98 5.60 0.25 2.27 192.92 1Treatment is equal to number of days on concentrate diet 2COG = Cost of gains per day live weight

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191 Table E-4. Final cost comparisons on a live weight basis for 8 head Treatment 0 Day 42 Day 84 Day 1. Gross income at Day 0 (summed from E-2, h) 3728.10 3682.43 3776.75 2. Gross income post feeding (summed from E-2, i) 0.00 4489.66 5761.56 3. Interest on Day 0 profit (5% annual) 0.00 21.30 43.46 4. Total income potential if not fed (line 1 + line 3) 0.00 3703.73 3820.21 5. Income over Day 0 if fed (line 2 – line 1) 0.00 807.23 1984.81 6. Income over Day 0 cost (line 5 – sum E-3,h) 0.00 13.15 441.45 Income from interest only/hd (line 3/8) 0.00 2.66 5.43 Fed profit/hd (line 6/8) 0.00 1.64 55.18 Profit difference (line 6 – line 3) 0.00 (-8.15) 397.99 Profit difference/hd (line 6 – line 3 divided by 8) 0.00 (-1.02) 49.75

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192 Table E-5. Final cost comparisons on a hot carcass weight basis for 8 head Treatment 0 Day 42 Day 84 Day 1. Gross income at Day 0 (Live weight * DP = HCW) 4325.78 4158.58 4131.75 2. Gross income post feeding (sold on rail, based on HCW 5-2) 0.00 5109.05 6125.11 3. Interest on Day 0 profit (5% annual) 0.00 23.93 47.54 4. Total income potential if not fed (line 1 + line 3) 0.00 4182.51 4179.29 5. Income over Day 0 if fed (line 1 – line 2) 0.00 950.47 1993.36 6. Income over Day 0 – costs (line 5 – sum E-3,h) 0.00 156.39 450.00 Income from interest only/hd (line 3/8) 0.00 2.99 5.94 Fed profit/hd (line 6/8) 0.00 19.55 56.25 Profit difference (line 6line 3) 0.00 132.46 402.46 Profit difference/hd (line 6 – line 3 divided by 8) 0.00 16.56 50.31

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207 BIOGRAPHICAL SKETCH Alexander Michael Stelzleni was born in Jefferson City, Missouri, on July 14, 1977. Alex spent most of his youth is Je fferson City, attending and graduating from Jefferson City Public High School in 1995. While growing up, Alex spent many summers and weekends at his grandparentsÂ’ in Gr anite City, IL, just outside of St. Louis. AlexÂ’s grandparents owned a small grocery st ore/butcher shop and a small farm in the area which started his interest in animal and meat sciences. As well, Alex owned and fed cattle with three friends thr ough high school and college furt hering his interest in the animal sciences field. Upon graduating from high school, Alex pursu ed a bachelorÂ’s degree in animal science-beef production from Missouri State University (formerly Southwest Missouri State University) in Springfield, MO. While at Missouri State University, Alex was actively involved in Alpha Gamma Sigma, an agricultural professional and social fraternity, holding several pos itions including Treasurer and President. Alex was also actively involved with Delta Tau Alpha, an ag ricultural honor societ y, and the Presidents Club, which served as a liaison organizati on between the different clubs in the Department of Agriculture and agricultura l faculty and alumni. While Alex was attending Missouri State Univ ersity he was awarded the Christian Robert Hirsch scholarship, two Sigma awards for scholarship and inducted in to the Order of Omega and Delta Tau Alpha Honor Societies. As well, while at Missouri State University Alex became proficient in live animal sonogram.

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208 After obtaining his Bachelor of Science degr ee Alex started his Master of Science degree at the University of Arkansas in th e discipline of animal science-beef breeding and genetics under the guidance of Dr. A. H. Brown, Jr. Alex’s thesis was titled Genetic Parameter Estimates of Yearling Live Anim al Ultrasonic Measurements in Brangus Cattle . This project was conducted with some of the data that Alex helped to collect as an undergraduate at Missouri St ate University. Alex earned his Master of Science degree at the University of Arkansas in August 2001. While at the University of Arkansas, Alex served as an instructor’s aide to several courses in cluding Introduction to Animal Science, Breeding and Genetics, and Animal Be havior. Alex was also actively involved with the Graduate Student Association and was inducted into Gamma Sigma Delta Honor Society. Along with working on his master’s degree, Alex was employed with Tyson Inc. Poultry Division, Springdale, Arkansas , as a Quality Control Technician and Management Trainee from July 1999 through May 2001. From January 2000 through September 2001, Alex was also employed by Dr. Tom Yazwinski as a Research Assistant and Assistant Herdsman for the University of Arkansas Physiology and Parasitology Farm. In September 2001 Alex accepted a positi on as Extension Assistant – Program Coordinator for the Department of Animal Sciences at the University of Florida. In August 2002 Alex decided to pursue his academic goals and returned to school to obtain his Doctorate of Philosophy in animal sciences – meat science under the direction of Dr. D. Dwain Johnson. The primary responsibilities for Alex while working on his PhD included serving as the Hazard Analysis Cri tical Control Points Coordinator for the University of Florida Meats Processing Center and serving as an instructor’s aide to

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209 undergraduate meat science and beef producti on courses. Alex wa s actively involved with various extension programs while at the University of Florida, as well as being active in the Graduate Student Associati on. He was also honored as one of the Department of Animal Science nominees for the Jack Fry Graduate Teaching Award for the College of Agricultural and Life Sciences. While working on his PhD, Alex met Eli zabeth Lindsay Steidl and married her on December 18, 2004. Elizabeth was working on he r bachelorÂ’s degree in equine science and is currently working on her Master of Science degree in e quine nutrition. Upon graduation Elizabeth plans to pursue her goals of working in the equine industry while Alex plans to pursue his goals of work ing in academia as a professor.