Citation
Effect of Castration Technique on Beef Calf Performance, Residual Feed Intake, and Inflammatory Response

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Title:
Effect of Castration Technique on Beef Calf Performance, Residual Feed Intake, and Inflammatory Response
Creator:
Warnock, Thomas
Place of Publication:
[Gainesville, Fla.]
Publisher:
University of Florida
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Language:
english
Physical Description:
1 online resource (84 p.)

Thesis/Dissertation Information

Degree:
Master's ( M.S.)
Degree Grantor:
University of Florida
Degree Disciplines:
Animal Sciences
Committee Chair:
Thrift, Todd A.
Committee Members:
Hersom, Matthew J.
Lamb, Graham
Irsik, Max
Graduation Date:
8/7/2010

Subjects

Subjects / Keywords:
Beef ( jstor )
Calves ( jstor )
Castration ( jstor )
Cattle ( jstor )
Feed conversion ratio ( jstor )
Feed intake ( jstor )
Feedlots ( jstor )
Hens ( jstor )
Plasmas ( jstor )
Weaning ( jstor )
Animal Sciences -- Dissertations, Academic -- UF
beef, castration, cattle, inflammation, intake, performance
Genre:
Electronic Thesis or Dissertation
bibliography ( marcgt )
theses ( marcgt )
government publication (state, provincial, terriorial, dependent) ( marcgt )
Animal Sciences thesis, M.S.

Notes

Abstract:
The objective of this study was to examine the effect of castration method on daily feed and water intake, calf performance, residual feed intake, and inflammatory reaction. Brangus (n = 45) and Angus (n = 30) male calves weighing 226 plus or minus 34 kg (200 plus or minus 26 days of age) were placed in a GrowSafe 4000 feed intake facility 7 days post weaning (15 calves/pen; 7-8 calves/feed node). Body weight gain, feed intake, and water intake were recorded over an 84-d period. Calves were offered a mixed diet (TDN = 67.3% and CP = 12.2%, DM = 89%) ad libitum. Calves were adapted to the facility for 21 d prior to the start of the trial. Shrunk BW was recorded on d 0, 14, and 84; full BW was recorded on d 7, 28, 42, 56, and 70. On d 0 calves were assigned to one of five treatments (n = 15 head/treatment): 1) control steers were castrated surgically prior to weaning at an average age of 52 d (range: 8-85 d) (CON); 2) intact bulls (BULL); 3) bulls castrated by the Callicrate Bander (No-Bull Enterprises, LLC, St. Francis, KS; BAN); 4) bulls castrated surgically using the Henderson castration tool (Stone Mfg & Supply Co., Kansas City, MO; HEN) and 5) bulls castrated surgically utilizing emasculators (SUR);. During the first 14 days post-castration (post-castration period), BAN calves gained slower (P = 0.009) than CON (0.10 vs. 0.68 kg/d) and tended to gain slower (P = 0.08) than BULL calves (0.10 vs. 0.48 kg/d). In addition, CON calves gained more (P = 0.04) than HEN and SUR, 0.68, 0.24, and 0.22 kg/d, respectively. Average daily gain for d 0 to 84 was similar for all treatments. Feed intake for the first 14 days post-castration as well as over the entire 84 d experiment was similar (P = 0.76 and P = 0.92, respectively). When feed intake was compared as a % of BW, intake d 0 to 14 and d 0 to 84 was similar (P > 0.10) for all treatment groups. Water intake for the first 14 days post-castration and over the entire 84 d experiment were similar (P = 0.38 and P = 0.72, respectively) for all treatment groups. Residual feed intake from d 0 to 14 was decreased (P < 0.05) for CON and BULL compared to SUR and intermediate and similar (P > 0.10) to BAN and HEN. Residual feed intake d 0 to 84 and G:F ratio d 0 to 14 and d 0 to 84 were similar (P > 0.10) among all treatments. Plasma ceruloplasmin concentration tended to be different (P = 0.10) among treatments during the post-castration period. CON had decreased (P < 0.05) plasma ceruloplasmin concentration compared to BULL and HEN during d 0 to 14 and tended to have decreased (P = 0.05) plasma ceruloplasmin concentration compared to SUR. BULL, BAN, HEN, and SUR had similar (P > 0.10) plasma ceruloplasmin concentration d 0 to 14. Plasma haptoglobin concentration was similar (P > 0.10) among treatments d 0 to 14. Our results indicate that method of castration did not have a long-term impact on performance or efficiency of weaned calves. ( en )
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis:
Thesis (M.S.)--University of Florida, 2010.
Local:
Adviser: Thrift, Todd A.
Statement of Responsibility:
by Thomas Warnock.

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Embargo Date:
10/8/2010
Resource Identifier:
004979766 ( ALEPH )
705932494 ( OCLC )
Classification:
LD1780 2010 ( lcc )

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1 EFFECT OF CASTRATION TECHNI QUE ON BEEF CALF PERFORMANCE RESIDUAL FEED INTAKE AND INFLAMMATORY RESPONSE By THOMAS MICAJAH WARNOCK III A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFI LLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2010

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2 2010 Thomas Micajah Warnock III

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3 To my parents, Tommy and Pam Warnock

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4 ACKNOWLEDGMENTS I would most of all like to thank my God for providing opport unities to learn and grow here at the University of Florida. I would also like to thank Dr. Todd Thrift for affording me the opportunity to continue my education, and fo r all the visits, guidance, support and encouragement he provided to me over my time i n the Animal Sciences Department Dr. Thrift allowed me to participate in quality research that will hopefully enrich the animal husbandry practices in the beef industry I will forever be grateful to him for that. I would also li ke to thank my supervisory committee, to Dr. Matt Hersom for always being willing to answer questions and discuss challenges I was facing, to Dr. Cliff Lamb for the unending help with statistics and encouragement throughout the experiment, to Dr. Irsik for providing tremendous vete rinarian insight throughout the experiment, support throughout my time here at the University of Florida and encouraging me to forge ahead in my academic endeavors. I wish to thank Danny Driver, Bert Faircloth, and the crew at the Santa Fe Beef Unit for as sistance in procuring the calves for this trial. I would also like to thank the crew at the North Florida Research and Education Center, Mr. Don Jones, Mr. Harvey Standland, and Mr. David Thomas. Without the help of these gentlemen none of my research woul d have been accomplished. Also, thank you to Dr Travis Maddock for the endless availability and help with statistics and experimental design. A special thank you to Dr. John Arthington and his lab in Ona, FL for help with lab analysis and statistical assi stance throughout the trial. I want to express my immense gratitude to my parents and sister Tommy and Pam and Brooke Warnock. My Dad is my best friend and without the encouragement and intense guidance over the past 2 years I would have certainly never attained a

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5 graduate degree. I would like to thank my Mom for the love and support as well, but also for the always being available and willing to visit. My sister i s as genuine and Godly of a woma n as I know and she never failed to support me, I will forev er be grateful to her for that. Without the love and Christian influence of my parents and sister none of this would have been attainable. I would also like to my future wife, Crystal Mathews, for the understanding, encouragement, and unwavering Christian influence. I would also like to than k her for being willing to spend the rest of her life with someone as cantankerous as me.

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6 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 8 LIST OF FIGURES ................................ ................................ ................................ .......... 9 ABSTRACT ................................ ................................ ................................ ................... 11 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 13 2 LITERATURE REVIEW ................................ ................................ .......................... 15 Castration ................................ ................................ ................................ ............... 15 Purpo se of Castration ................................ ................................ ....................... 15 Methods of Castration ................................ ................................ ...................... 16 Surgical methods ................................ ................................ ....................... 17 Bloodless methods ................................ ................................ ..................... 17 Experiments evaluating castration method ................................ ................ 19 Stress associated with castration ................................ ............................... 21 Utilizing pain mitigation techniques ................................ ............................ 24 Effects of Castration on Performance ................................ ................................ ..... 25 Effect of Castration on Carcass Merit and Meat Quality ................................ ... 28 Effect of Age at Castration on Carcass Characteristics ................................ .... 30 Residual Feed Intake ................................ ................................ .............................. 32 Utilization of the GrowSafe System ................................ ................................ .. 34 Genetic and Phenotypic Basis ................................ ................................ .......... 35 Physiological Basis ................................ ................................ ........................... 36 Feeding Behavior ................................ ................................ ............................. 37 Carcass Parameters ................................ ................................ ......................... 39 3 EFFECT OF CASTRATION TECHNIQUE ON BEEF CALF PERFORMANCE, RESIDUAL FEED INTAKE, AND INFLAMMATORY RESPONSE .......................... 41 Introduction ................................ ................................ ................................ ............. 41 Materials and Methods ................................ ................................ ............................ 42 Animals and Treatments ................................ ................................ ................... 42 Sampling and Analysis ................................ ................................ ..................... 44 Results and Discussion ................................ ................................ ........................... 46 Average Daily Gain ................................ ................................ .......................... 46 Feed Intake ................................ ................................ ................................ ...... 48 Water Intake ................................ ................................ ................................ ..... 51 Feed Efficiency ................................ ................................ ................................ 53

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7 Acute Phase Proteins ................................ ................................ ....................... 54 Implications ................................ ................................ ................................ ............. 57 APPENDIX : DIET COMPOSITION ................................ ................................ ............... 77 LIST OF REFERENCES ................................ ................................ ............................... 78 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 84

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8 LIST OF TABLES Table page A 1 Ration composition ................................ ................................ ............................. 77 A 2 Nutrient composition ................................ ................................ ........................... 77

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9 LIST OF FIGURES Figure page 3 1 Effect of castration technique on average daily gain d 0 14 ............................ 60 3 2 Effect of breed on average daily gain d 0 14 ................................ ................... 60 3 3 Effect of castration technique on average daily gain d 0 84 ............................ 61 3 4 Effect of breed on average daily gain d 0 84 ................................ ................... 61 3 5 Effect of castration tech nique on ADG d 7 70 by period ................................ .. 62 3 6 Effect of castration technique on ADG d 7 2 8 ................................ .................. 62 3 7 Effect of castration technique on daily feed intake d 0 14 ................................ 63 3 8 Effect of the treatment*day interaction on daily feed i ntake d 0 14 .................. 63 3 9 Effect of breed on daily feed intake d 0 14 ................................ ...................... 64 3 10 Effect of castration technique on weekly feed intake d 0 84 ............................ 64 3 11 Effect of treatment*week interaction on weekly feed intake d 0 84 .................. 65 3 12 Effect of breed*week interaction on weekly feed intake d 0 84 ........................ 65 3 13 Average weekly ambient temperature readings for Marianna, FL d 0 84. ....... 66 3 14 Effect of castration technique on average daily feed intake as a percentage of BW on an as fed basis d 0 84 ................................ ................................ ...... 66 3 15 Effect of breed on average daily feed intake as a percentage of BW on an as fed basis d 0 84 ................................ ................................ ............................... 67 3 16 Effect of castration technique on feeding behavior early post castra tion ............ 67 3 17 Effect of the treatment*day interaction on water intake d 0 14 ........................ 68 3 18 Effect of the breed*treatment interaction on daily water in take d 0 14 ............. 68 3 19 Effect of the breed*day interaction on daily water intake d 0 14 ...................... 69 3 20 Daily ambient tempe rature d 0 14 in Marianna, FL ................................ .......... 69 3 21 Effect of castration technique on weekly water intake d 0 84 .......................... 70 3 22 Effect of the breed*week inte raction on weekly water intake d 0 84 ................ 70

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10 3 23 Effect of castration technique on G:F ratio d 0 14 ................................ ............ 71 3 24 Effect of castratio n technique on G:F ratio d 0 84 ................................ ............ 71 3 25 Effect of breed on G:F ratio d 0 14. Breed effect: P = 0.25. ............................. 72 3 26 Effect of breed on G:F ratio d 0 84 ................................ ................................ .. 72 3 27 Effect of castration technique on RFI d 0 14 ................................ .................... 73 3 28 Effect of castration technique on RFI d 0 84 ................................ .................... 73 3 29 Effect of the treatment*day interaction on plasma ceruloplasmin concentration post cast ration ................................ ................................ .............. 74 3 30 Effect of bre ed on plasma ceruloplasmin concentration post ca stration ............. 74 3 31 Effect of the treatment*day interaction on plasma haptoglobin concentration post castra tion ................................ ................................ ................................ .... 75 3 32 Effect of breed on plasma haptoglobin concentration post cas tration ................ 75 3 33 Effect of the breed*day interaction on plasma haptoglobin concentration post c a stration ................................ ................................ ................................ ............ 76

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11 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science EFFECT OF CASTRATION TECHNI QUE ON BEEF CALF PERFORMANCE, RESIDUAL FEED INTAKE AND INFLAMMATORY RESPONSE By Thomas Micajah Warnock III August 2010 Chair: Todd Thrift Major: Animal Sciences The objective of this study was to examine the effect of castration method on daily feed and wate r intake, calf performance, residual feed intake and inflammatory reaction Brangus (n = 45) and Angus (n = 30 ) male calves weighing 226 34 kg (200 26 days of age) were placed in a Gro wSafe 4000 feed intake facility 7 d ays post weaning (15 calves/pen; 7 8 calves/feed node). Body weight gain feed intake, and water intake were recorded over an 84 d period. Calves w ere offered a mixed diet (TDN = 67.3% and CP = 12.2%, DM = 89%) ad libitum. Calves were adapted to the facility for 21 d prior to the start o f the trial. Shrunk BW was recorded on d 0, 1 4, and 84; full BW was recorded on d 7, 28, 42, 56, and 70. On d 0 calves were assigned to one of five treatments (n = 15 head /treatment): 1) control steers were castrated surgically prior to weaning at an avera ge age of 52 d ( range: 8 85 d) (CON); 2) intact bull s (BULL) ; 3) bulls castrated by the Callicrate Band er (No Bull Enterprises, LLC, St. Francis, KS; BAN); 4) bulls castrated surgically using the Henderson castration tool (Stone Mfg & Supply Co., Kansas Ci ty, MO; HEN) and 5) bulls castrated surgically utilizing emasculators (SUR) ; During the first 14 d ays post castration (post castration period) BAN calves gained slower (P = 0.009) than CON (0.10 vs. 0.68 kg/d) and tended to gain

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12 slower (P = 0.08) than BU LL calves ( 0.10 vs. 0.48 kg/d). In addition CON calves gained more (P = 0.04) than HEN and SUR, 0.68, 0.24, and 0.22 kg/d, respectively. Average daily gain for d 0 to 84 was similar for all treatments. Feed intake for the first 14 days post castration as well as o ver the entire 84 d experiment was similar (P = 0.76 and P = 0.92, respectively) W hen feed intake was compared as a % of BW intake d 0 to 14 and d 0 to 84 was similar (P > 0.1 0 ) for all treatment groups. Water intake for the first 14 d ays post c astration a nd over the entire 84 d experiment were similar (P = 0.38 and P = 0.72, respec tively) for all treatment groups Residual feed intake from d 0 to 14 was decreased (P < 0.05) for CON and BULL compared to SUR and interm ediate and similar (P > 0.1 0 ) to BAN and HEN. Residu al feed intake d 0 to 84 and G:F ratio d 0 to 14 and d 0 to 84 were similar (P > 0.1 0 ) among all treatments. Plas ma ceruloplasmin concentration tended to be different (P = 0.1 0 ) among treatments during the post castration period. CON had decreased (P < 0.05) plasma ceruloplasmin concentration compared to BULL and HEN during d 0 to 14 and tended to have decreased (P = 0.05) plasma ceruloplasmin concentration compared to SUR. BULL, BAN, HEN, a nd SUR had similar (P > 0.1 0 ) plasma cerulop lasmin concentration d 0 to 14. Plasma haptoglobin concentration was similar (P> 0.1 0 ) among treatments d 0 to 14. Our results indicate that method of castration did not have a long term impact on performance or efficiency of weaned calves.

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13 CHAPTER 1 INT RODUCTION Ca stration of male beef calves may potentially cause pain and a subsequent period of decreased performance as a result of decreased appetite Feed efficiency may also be negatively affected by this pain induced period of poor performance. Knowle dge of which castration methods elicit the least amount of pain and reduction in performance will provide beef producers with improved animal husbandry practices. Castration is a common animal husbandry practice in the United States. Castration of male bee f calves eliminates intact male be havior and improves the decrease d quality grade, tenderness and consumer acceptability observed in beef from intact ma le calves (Lents et al., 2006; Seideman et al., 1982) It is known that invasive methods of castration i nduce some degree of pain in male calves evidenced by decreased performance and morbidity post castration (Stafford et al., 2002; Brazle, 1992) There are numerous methods of castration commonly used on beef operations (NAHMS, 1997) Identifying methods of castration that cause decreased str ess on the calf will provide producers with a production practice that sacrifices the least amount of productivity, and a means of b eing pro active about potential animal welfare concern s Currently, feed efficiency is c ommonly discussed in th e beef industry. If a particular castration technique causes a decreased stress on a calf thus decreasing the lag in perfor mance, and reduction in appetite then that method may be advantageous in the way of feed efficiency. Feed effi ciency in beef production systems is quantified in several ways, such as feed to gain ratio (F:G), gain to feed ratio (G:F), and residual feed intake (RFI). Feed to gain ratio and G:F are measured as unit of feed consumed per unit of weight gain and

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14 units of weight gain per unit of feed consumed, respectively. These methods may be useful ; however selecting for improved ratios can cause a subsequent increase in cow size. Residual feed intake however is divergent of matur e body size and growth rate. Residu al feed intake is the units of feed consumed above or below what the calf was expected to consume for a given body size and growth ra te. Methods of castrati on that result in decreased poor performance and increas ed feed efficiency could potentially decreas e RFI. T hese animals consume less feed than they were expected, while maintai ning similar average daily gain and body size as their counterparts.

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15 CHAPTER 2 LITERATURE REVIEW Castration Castration can increase the value of male beef calves. Troxel and Ba rham (2007) reported that in 2000 and 2005 steers sold through Arkansas sale bar ns received premiums of $ 6.02 0.08 and $ 6.48 0.09/45.45 kg over the mean of all calves ($ 92.91 and $ 118.32/45.45 kg) selling price, respectively. The reasons for this a re numerous but mostl y pertain to desirability of castrate d over intact male s within the United S tates beef industry T here are clearly defined segments in the beef industry: the seedstock producer, the cow/calf producer, stocker/backgrounder, feedlot ope rator and packer A ll of these segments play a n intricate role in why castration is essential from a management, facilities, quality, marketing, and consumer acceptability standpoint. Castrates differ from intact males with regards to gain, carcass chara cteristics, carcass composition, and meat quality. Seideman et al. (1982) reported that the disadvantages associated with intact males are aggressive behavior, undesirable odors and flavors, lower quality grade, lower meat tenderness, and undesirable meat color. Purpose of C astration More than 17 million male calves between the ages of 1 d and 1 y ea r of age are castrated annually in the United States (Lents et al., 2006). Castration can effectively reduce or diminish intact male behavior and undesirable ca rcass attributes that are observed in intact males. Consumers in the U. S. value the tenderness, juiciness, and flavor associated beef f rom castrated male beef calves (Heaton et al., 2004) Cow calf p roducers often cite concerns of decreased growth rate as sociated with castration of male calves (Lents et al., 2006). Consequently, many intact male calves

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16 will be sold at weaning. The task of castration often falls on the first buyer of the calf shortly after weaning. Unfortunately, castration becomes increasi ngly traumatic as calves grow older and heavier. In the United States the majority of male calves finished in commercial feedlots are castrates, however this is not true in all countries around the world. Some countries utilize the intact male for beef pro duction because of their advantages in terms red meat yield, and efficient growth compared to castrates (Seideman et al., 1982) Methods of C astration In the beef industry the re a re many accepted methods of castration for beef cattle. Some methods are more suitable for certain situations compared to other methods T he methods availab le for castration can be broadly classified as surgical and bloodless Surgical methods are more invasive and perceivably more painful than bloodless methods of castration. Surg ical methods are comprised of practices such as knife cutting, emasculator method, and Henderson castrating tool (Stone Manufacturing and Supply Co., Inc., Kansas City, MO 64127) Bloodless methods are available through banding techniques, Burdizzo emascul atomes and chemical castration In 19 97 the United States National Animal Health Monitoring S ystem (NAHMS) reported that 55.4 percent of cow calf producers utilized surgical castration as the primary method of castration for male beef calv es. However her d size tended to be a factor in the method used. This was evidenced by 80.5 % of operations with 300 head utilizing surgical castration O perations with 50 head or less were almost equally split between a using surgical method (49.4 % ) or a banding metho d (43.7 % ; NAHMS, 1997 ).

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17 Surgical methods Surgical castration can be accomplished through a variety of methods and combinations of methods Jensen et al. (2006) describes that t he initial incision or opening of the scrotum can be accomplished via a knife o r scalpel. The testicles should be pushed into the upper portion of the scrotum with the lower half of the scrotum being removed, this provi des adequate drainage. In Addition a Newberry castrating knife (Jorgensen Laboratories, Loveland, CO 80538) may be utilized during the surgical castration procedure. This tool is used to incise the scrotum on the sides leaving an anterior and posterior flap for access to the testicles and drainage. Once the scrotum has been incised using any of these methods, the testi cles must be removed by severing the spermatic cords, scraping of the spermatic cord to facilitate gradual separation of the tissues and vesse ls, gently pulling the testicle until the spermatic cord break s utilization of the emasculator t ool, or applying the Henderson castration t ool. The same author adds that t he emasculator is an option for removing the testicles during surgical castration by cutting the spermatic cord while also crushing the blood vessels to mitigate post castration bleeding and hemorrh age. Furthermor e, the Henderson castration tool is a process designed to be more effective on older bulls. The tool is designed to fit into a variable speed drill and clamped on the spermatic cord proximal to the testes. The drill is then slowly rotated un til the testicle is removed by approximately 20 rotations of the drill (Jensen et al., 2006). Bloodless methods Bloodless castration is comprised of a variety of methods that may also successfully accomplish castration of male cattle with minimal blood los s and perceivably less stress. Capucille et al. (2002) reports that t hese methods involve

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18 interrupting the blood supply to the testes and scrotum without causing hemorrhaging The processes commonly used are the elastrator, Callicrate Bander (No Bull Enter prises, St. Francis, KS 67756) Eze Bloodless Castrator (Out West Manufacturers, St. Ignatius MT 59865) California Bander (Inosol, LLC, El Centro, CA 92243) and e masculatomes. El astrators stretch the small rubber bands to allow it to be applied around th e scrotum as close to the body as possible. The Callicrate Bander and Eze Bloodless Castrat or require larger elastic tubes that are fitted around the scrotum and then tightened by a ratcheting mechanism on the tool. A metal grommet is then crimped around t he band to hold tension on the band. The tools have been designed with a tension indica tor because under tightening may cause compl ications and over tightening may potentially lead to broken bands and unsuccess ful castration. The California Bander differs more than the other methods however it does require large elastic bands. The bands are manually stretched around the scrotum and fitted into a metal clip, which hold tension on the band. There is a risk of anaerobic infecti ons such as tetanus when utilizi ng these banding methods. I t has been recommended that calves be vaccinated with tetanus toxoid 7 to 10 days prior to banding and boostered at castration to mitiga te the risk of tetanus (Anderson, 2007) Another method of bloodless castration is the emascu latome method. This method facilitates the castration of calves without the potential complication associated with either surgical castration or the banding procedure. The emasculatome accomplishes castration by crushing the spermatic cords without incisin g the scrotum; thus there is no open or bleeding tissue. However, this method is intended for u se in young immature

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19 male calves as older /heavier bulls tend to have larger cremaster muscles that may hinder proper crushing of testicular vasculature (Capucill e et al., 2002). Experiments evaluating castration method Previous resear ch has focused on method of castration and the subsequent effects on calf performance, mortality, morbidity, stress response, and carcass parameters. Zweiacher et al. (1979) compared the effects of elastrator ligation and emasculation, two methods of surgical castration, on feeder calf performance (180 and 175 kg average BW ) The elastrator ligation process included exposure of the testicles by partial removal of the scrotum and placin g an elastrator band on each spermatic cord. The testicles were then removed by severing the spermatic cord with emasculators two to four cm below each elastrator band. The ligation bands were applied in order to minimiz e post castration hemorrhaging. In o ther studies, researchers have compared surgical castration and the bloodless banding procedure. Chase et al. (1995) studied the effects of surgical castration utilizing the Newberry knife and emasculator versus the banding method using large rubber bands (EZE Bloodless Castrator) on bulls nearing maturity (a verage BW 420 + 12.1 kg) Surgical castration in this study was carried out by incising the scrotum with a Newberry knife. The testicles were then removed by applying the emasculator to each individu al spermatic cord. Banding was carried out using latex rubber bands applied with the EZE Bloodless Castrator where an individual latex rubber tube was fitted around the scrotum as close to the testicles and as far from the body as possible. Lents et al. (200 1) compared banding with large latex bands and surgical castration via knife cutting utilizing 120 + 2 kg suckling bull calves The b ander was used to ratchet the elastic band tight around the scrotum with the testicles in the distal

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20 portion of the s crotum The surgical treated bulls were castrated by removing the distal third of the scrotum, exposing the testicles, and severing the spermatic cords with a knife. In another study done by Lents et al. (2006) the surgical castration by scalpel was evaluated in compa rison with banding with small rubber bands The banding method was carried out by pulling the testes into the distal portion of the scrotum and two small rubber bands were applied proximal to the test es. Surgical castration was performed by removing the lower third of the scrotum, testicles were exposed and spermatic cords severed uti lizing a scalpel. Stafford et al. (2002) evaluated the response of two to four month old calves with a mean BW of 95.5 + 0.97 kg to five different methods of castration. The methods of ca stration were banding with small rubber bands band ing with large latex bands surgical castration by pulling testicles, surgical castration with t esticles removed by emasculators and bloodless castration by e masculatomes. Immunization a gainst gonadotropin releasing hormone (GnRH) or GnRH keyhole limpet hemocyanin (KLH) has been shown to be effective in diminishing bullish behavior and maintaining comparable feedlot performance and carcass merit to conventionally castrated steers. Adams a nd Adams (1992) investigated feedlot performance of GnRH immunized Bos taurus calves (278.8 + 2.8 kg) by observing unimmunized bulls (intact male calves), GnRH immunized one time calves, and GnRH immunized with booster 8 weeks after first immunization c alv es in a feedlot setting. Gonadotropin releasing hormone antigen injections were administered subcutaneously in the dorsal portion of the neck Price et al. (2003) described that through the same immunization procedure used in Adams and Adams (1992) that t h ey observed a decrease in bullish behavior in

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21 the feedlot. A comparison of these methods and results will be discussed in subsequent sections. Stress associated with castration When male cattle are castrated by any o f the methods discussed, a certain level of pain i s elicited This pain may potentially cause poor calf performance as a result of decreased feed and w ater intake It may be that the pain is not the sole inhibitor of performance but that suppressed immune function resulting from release of gluco corticoids during an inflammatory reaction leads to increased incidence of morbidity and su bsequent loss of appetite. In an attempt to quantify pain it may be advantageous to evaluate blood constituents, plasma concentrations of some blood constituents may be pivotal in determining acuteness and duration of pain potentially elicited by an inflammatory response to stressors such as castration. Quantifying pain associated with animal husbandry practices such as castration is extremely difficult and somewhat s ubjective. There are parameters that researchers may be able to monitor and assist them in making assumptions with respect to how much pain the animal may be experiencing and the duration of that pain response. Some of the ph ysiological, behavioral, and pe rformance responses have been reviewed by Capucille et al. (2002). Physiological responses including c ortisol concentrations, acute phase protein concentrations, and white blood cell counts may be monitored. Behavior can potentially serve as an indicator o f pain and or stress, deviations in behavior from status quo or that of the cont rols are viewed as response to pain. Chase et al. (1995) observed the effects that surgical castration (SUR) and banding (BAN) had on plasma cortisol concentration and white bl ood cell counts using older intact male calves of thre e different breeds; Angus (400 11.6 kg, 21.4 0.24

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22 mo), Brahman (465 8.2 kg, 20.3 0.17 mo), Hereford (395 16.4 kg, 21.2 0 .34 mo). P lasma cortisol concentra tion for surgically castrated calves increased immediately post castration compared to BAN However, 2 d post castration plasma cortisol concentration for both SUR and BAN were similar, both being higher than that of controls Castration impacted white blood cell counts. Surgically castrated calves and BAN had 20.2 and 25 % greater white blood cell counts d 2 post castration compar ed to controls The acute pain response associate d with SUR was immediate and of short duration from d 0 pre treatment to d 0 post castration plasma cortisol level s increased for SUR 3.2 ng/mL The pain response associated with BAN was delayed, of less initial intensity, and also short in duration from d 0 pre treatment to d 0 post castration plasma cortisol increased 0.1 ng/mL Day 0 pre treatment to d 2 post cas tration plasma cortisol increased 2.0 ng/mL for SUR, 1.1 ng/mL for BAN and decreased 1.6 ng/mL for CON (castrate vs. CON P < 0.04) O ther researchers reported that banding of Friesian cross calves (95.5 + 0 .97 kg 2 to 4 mo ) with large latex bands elicited an immediate and significant increase in the plasma cortisol concentration above pre tr eatment concentrations. T he increase in plasma cortisol concentrations in banded calves was significantly greater than that of the surgically castrated calves between 0 .5 an d 2.5 h post castration. In surgical ly castrated calves there was a numerical increase in plasma cortisol concentration over t he pre treatment concentration (Stafford et al., 2002). Thus, i t is possible that age and or weight may be a factor in stress response associated with castration. Friesian bulls of intermediate age (173 2 kg) were utilized to compare the effects of castration method on plasma cortisol concentration (F isher et al., 1996) The authors

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23 reported that surgical castration and emasc ulatome castration method caused an acute increase in plasma cortisol concentrations post castration and it remained elevated for up to 8 h. In addition the surgically castrated calves had a greater peak and mean plasma cortisol concentration than did the emasculatome castrated calves. This may indicate that surgically castrated calves had a greater initial stress and inflammatory response (F isher et al., 1996). In two experiments conducted by Fisher et al. (2001) Angus, Angus x Fr iesian, and Simmental cal ves (399 2.8 kg ; Exp. 1 ) and Angus calves (238 3.4 kg ; Exp. 2 ) were castrated by surgical or banding methods Plasma cortisol concentrations and plasma haptoglob in concentrations were observed daily as indicators of pain response to the respective cast ration methods. Plasma cortisol concentrations were not different for the two castrate groups in Exp. 1; however plasma cortisol concentration on d 7 and 14 post castra tion were significantly lower for intact bulls compared to surgical castrates ( 34 nmol/ L vs. 60 nmol/L; 43 nmol/L vs. 73 nmol/L, respectively) Plasma haptoglobin was observed to evaluate the inflam matory response to castration. The plasma haptoglobin concentrations for the surgically castrated male cal ves were significantly greater compared to the banded and intact bulls on d 1, 2, and 4; with banded and intact bulls being similar Afte r d 4 concentrations of plasma haptoglobi n were similar regardless of treat ment. A nother acute phase protein, f ibrinogen, was analyzed from blood samples coll ected and results closely mirrored those of the plasma haptoglobin concentrations in Exp. 1 In Exp. 2 there were no differences in plasma cortisol concentration regardless of castration method Plasma haptoglobin concentration was significantly greater fo r surgical castrates than for banded calves on d 2 and 4.

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24 Capucille et al. (2002) suggested that the growing concern for the welfare of our food animals and the pain associated with these manag ement practices. These authors concluded that the largest barri er to developing more stringent policies for mediation of pain associated with animal agriculture management techniques is the inability to accurately asse ss pain in animals. In addition anthropomorphism can be very problematic with regards to the public perception of common management practices such as castration, dehorning, tail docking, and ear notching. The complexities and subjectivity associated with applying human responses to experiencing pain to animal behavior and responses to stress and pain sti muli may be intensely misunderstood (Capucille et al., 2002) Erickson (1984) suggests that pain is a complex physiological phenomenon; it is hard to define satisfactorily in human beings and it is extremely difficult to recognize and interpret in animals. Utilizing pain mitigation techniques It is ev ident that methodology for quantifying pain in beef cattle remains unclear. Applying the best method for reducing the pain response to an injurious procedure will benefit the welfare of animals (Tin g et al., 20 03). Thirteen month old cattle (307 + 5.3 kg) were castrated by the e masculatomes and then administered an anti inflammatory ( ketoprofen; K), local anesthesia ( lidocaine HCL; LA), or caudal epidural anesthesia ( lidocaine HCL and xylazine HCL; EPI). The eff ects of analgesics on plasma cortisol, acute phase proteins, and interferon ga mma production were recorded. S ystemic analgesia with K was more effective in mitigating the acute pain response (cortisol) and suppressed immune f unction associated with emascul atome castration than LA or EPI In addition, K or EPI were more effective than LA at minimizing pain related behavioral

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25 displays (Ting et al., 2003). It may be possible to ameliorate the pain associated with castration by administeri ng certain analgesics. Stafford et al. (2002) observed t hat in 2 to 4 mo nth old calves (95.5 + 0 .97 kg ) if local anesthesia was administered prior to banding with large latex bands or banding with small rubber rings acute pain and distress associated with both bloodless metho ds of castration was virtually eliminated In the same experiment, w hen surgical castration was applied either by severing spermatic cords or broken by traction t he local anesthesia was successful in decreasing pain during the incision but otherwise did n ot mitigate the pain and inflammatory response A dministration of ketoprofen along with local anesthesia virtually eliminated the acu te pain response associated for both surgical methods over the 5 d trial. Effects of Castration on P erformance As a result of pain, stress, and suppressed immune function, decreased performance and morbidity in male calves post castration is commonly observed T he method of castration that causes the least amount of decreased performance may be the method that causes the least pain and stress resulting in a reduction in animal welfare concerns. Brazle (1992) conducted two field trials to evaluate the effects of different methods of castration on the health and performance of stocker cattle. All calves were vaccinated, treated for external and internal parasites and implanted prior to the study. In the first experiment 496 cross bred steer and bull calves (115 kg) were purchas ed from sale barns in the South east United States. The purchased bull calves were either surgically cast rated ( n = 190 ) or banded with small rubber rings ( n = 188 ) and compared to purchased steer calves ( n = 118). Average daily gain of purchased steers was significantly greater compared to surgically castr ated calves and the banded

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26 calves (0.84 kg/d vs. 0.74 and 0.66 kg/d, respectively) M orbidity, mortality, and cost associated with medical treatment were reported to be similar am ong all treatments. In the second experiment 60 mixed breed steers and bulls (300 kg) were purchased S teers (n = 20) were compa red with surgically castrated bul ls (n = 20) and calves banded with large latex bands (n = 20). Purchased steers g rew significantly faster than banded calves evidenced by increased average daily gain (0.93 kg/d vs. 0.72 kg/d) and purchased steers gained s imilarly to the surgicall y castrated calves (0.93 kg/d vs. 0.80 kg/d). Other research has demonstrated that calves banded at 2 to 3 mo nths of age had i significantly greater average daily gai n compared to bulls surgically castr ated at 2 to 3 mo nths of age o r calves l eft intact (Lents et al., 2001). L ents et al. (2001) also reported that b ulls banded at weaning tended to ha ve decreased average daily gain during the 50 d p ost weaning Faulkner et al. (1992) used 6 to 9 mo old crossbred calves (214 + 19 kg) to investigate performance of male calves castrated surgically utilizing the Newberry knife to incise the scrotum and the emasculator to remove testes compared to intact male calves Surgically castrated calves had significantly decreased average daily gain compared with intact bulls (0.26 kg/d vs. 0.42 kg/d respectively ). Feed i ntake was similar between castrates and intact male calves, howe ver G:F was significantly increased for intact male calves compared to castrates. It may be that younger/ lighter male calves experience less pain, stress, and decreased performance as a result of castration. Bruns and Pritchard (2004) observed that bulls banded a t 9 mo nths of age grew slower for 29 d ays post banding than bulls surgic ally castrated at 2 to 3 mo nths of age The bulls banded at 9 mo nths of age had

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27 significantly greater dry matter intakes and were less effi cient as evidenced by greater F:G co mpared to bulls castrated at 2 to 3 mo nths of age This suggests that castrating bulls at younger ages may allow for hea ling prior to those calves ent ering a feedyard Lents et al. (2006) performed two experiments to investigate the effect of method and timing of castration on beef c alf performance. In Exp. 1 bulls banded and implanted at 2 to 3 mo nths of age had significa ntly greater pre weaning gain than bulls surgically castrated and implanted at 2 to 3 mo nths of age but were similar to control bulls; 0.94 kg/d, 0.90 kg/d and 0.91 kg/d, respectively. In this same study it w as reported that implanted steers banded a t wean ing had significantly decreased average daily gain during a 50 d post weaning period than both implanted steers banded at 2 to 3 mo nths of age and t hose surgically castrated at 2 to 3 mo nths of age (0.43 kg/d vs. 0.49 kg/d and 0.48 kg/d, respectively). In Exp. 2 it was observed that steers banded at birth and steers banded and implanted at birth had greater BW at weaning compared to intact bulls (245.0 kg, 241.3 kg, and 234.1 kg, respectively). Lents et al. (2006) concluded that delaying surgical or banding castration procedures to later than 6 mo nths of age reduced body weight gain f or at least 30 d ays post castration The author s surmised that p roducers should castrate bull calves as young as po ssible to decrease stress response and poor performa n ce. These results indicate that leaving male calves intact until weaning to maximize pre weaning performance is not truly advantageous because of the physiological factors regulating growth. In addition utilizing growth promoting implants in those early castrates may allow similar growth compared to their intact counterparts.

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28 Immunization against GnRH may be an effective method of chemical castration. Adams and Adams (1992) utilized 278.8 2.8 kg Bos taurus calves to compare GnRH immunized steers to intact male ca lves. Results indicated that immunization decreased gain numerically but not statistically. In another experiment Adams and Adams ( 1992) compared feedlot performance of intact male calves (CON), GnRH immunized steers (Anti GnRH), and surgically castrated steers (CAST; 325.2 2.8 kg). Results indicated that CON and Anti GnRH gained similarly but both gained more than CAST. The authors suggest that GnRH is an effective immunogen in male cattle. This method of immuno castration may be an alternative to invasi ve methods like surgical castration However, the authors indicated that the immunization against GnRH is most effective when carried out prior to significant testicular development. The application of these hormonal and chemical methods of castration in t he U.S. is uncommon coupled with being labor intensive. Effect of Castration on Carcass M erit and Meat Q uality Seideman et al. (1982) reported that intact males grow more rapidly, utilize feed more efficiently, and produce a higher yielding carcas s compare d to castrated male beef calves However, the disadvantages of the intact male include aggressive behavior; undesirable odors and flavors; lower quality grade; lower meat tendern ess and undesirable meat color. Price et al. (2003) reported that actively imm uniz ing male calves against GnRH may mediate bullish behavior in the feedlot, therefore reducing bruising, and potential reduced meat quality ca used by sex hormones Castration of male calves alters the p hysiological status of the calf, a s a result th e com position of growth changes. Typically castrated males deposit increased amounts of sub cutaneous fat as well as deposit ing increased intra muscular fat C astration of male calves

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29 facilitates the production of cattle that will yield a more consum er acceptab le product (Heaton et al., 2004). I n a review by Field (1971), it was reported that interest in utilizing intact male calves for meat production was growing. This growth was thought to be due to the declining demand for animal fat, increased emphasis on e fficiency, and the need for greater quantities of red meat for our rapidl y growing population. However, the demand for leaner beef is not what is being observed in the mark et place today. Some research indicates that consumers are willing to pay more for s teaks that have higher marbling both as a function of sensory ratings and visual eva luation (Killinger et al., 2004; Platter et al., 2005). Ability to select ca ttle that will manifest greater intramuscular fat at harvest has become decreasingly difficult t o accomplish through genetic selection and can be done to some extent without increasing subcutaneous fat (Gwartney et al., 1996 ). Some experiments reviewed by Field (1971) indicated that intact male calves had a 17% adva ntage over castrates in average dai ly gain, and b ulls were shown to be 13% more efficient. M arblin g scores were greater in steers than bulls, with percent intramuscular fat supporting this subjective evaluat ion. I n other studies reviewed by Field (1971) it was reported that young bulls may have enough intramuscular fat to grade choice T his may be a function of the lack of C ontinental breed type influence in the cattle utilized in these studies When Adams and Adams (1992) evaluated the carcass characteristics of male beef calves actively im munized against GnRH, they reported that immunized steers and control bulls performed similarly in terms of yield grade, longissimus muscle area, and hot carcass weight. However, surgically castrated steers in this same study had significantly increased yi eld grade, significantly decreased

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30 longissimus muscle area, and lighter hot carcass weights compared to control bulls and immunized steers. Effect of Age at Castration on Carcass C haracteristics In a study evaluating age at castration and its effects on gr owth and carcass quality, Knight et al. (2000) reported that c alves cast rated by banding with small rubber bands at birth had increased subcutaneous fat depth, bulls castrated at 12 mo nths of age had the least, an d bulls castrated at 6 mo nths of age were i ntermediate In another study Knight et al. (1999) observed the effects of the interval between castration and slaughter and its subsequent effects on carcass characteristics. The authors indicated that bulls produced carcasses that were 10 14% heavier th an steers and they concluded that for the intervals from castration to slaughter examined in this trial, post pubertal castration changed meat quality attributes of bulls to those more like steers while other characteristics changed more slowly and were fi nally intermediate between bulls and steers. However, it was not possible to capture the weight gain advantages of intact male calve s, castrate them at 17 mo nths of age and generate the meat quality of steers. They conceded that castrating bulls at differ ent ages could provide producers with a technique for manipulating meat quality attributes Worrell et al. (1987) indicated that it may be possible to improve carcass quality of late castrates or intact male calves by longer feeding pe riods; however this may also increase cost of produ ction, decrease feed efficiency and decrease average daily gain Champagne et al. (1969) reported that w hen comparing intact males with calves castrated at birth, 2, 7 and 9 mo nths of age ; it was observed that intact males had decreased intramuscular fat and subsequent ly decreased carcass grade compared to that of castrates. This agrees with a study performed by Heaton et al. (2004) where late

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31 castrated calves had significantly lower marbling scores than that of early castra ted mal e calves or those castrated at weaning The authors reported male c alves castrated at 9 mo nths of age had significantly lower marbling scores and carcass grades than all other castrate groups. Similar results were observed with respect to carcass fa t cover; bulls had significantly less than the cast rate groups and the calves castrated at 9 mo nths of age had significantly decreased subcutaneous fat compared to other castrate groups. As expected, bull s had larger longissimus area than castrates, with all the castrate groups be ing similar. B ulls had a significantly higher maturity score indicating that bulls may have darker lean and increased amounts of ossification in the cartilaginous buttons along the spinal column. O verall, yield was significantly g reater for bulls compared to the castrates. The results from sensory panel and Warner Bratzler shear were similar among all groups. However, juiciness ratings were slightly numerically greater for bulls even thought they had less marbling and lower carcass grades. Heaton et al. (2004) su ggested that in sensory panel evaluating consumer acceptability of early castrated male calves, calves castrated at weaning, and late castrated male calves; the early castrates were found to be more desirable w ith respects t o tenderness, juiciness, flavor and over all acceptability compared to the weaning castrates and the late castrates. T here appears to be pain and distress associated with most methods of castration the severity and duration remains unclear. It is possible that the decreased perfo rmance resulting from this pain and distress and subsequent morbidity can be mediated to some extent by castrating at earlier ages and lighter weights, u tilizing analgesics and possible application of implants to increase gain s and efficiency. T he pain and distress that is

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32 assumed to be present at the time of castration and po st castration may be a point of concern from a n animal welfare standpoint. A ttention must be given to this matter in order to be proactive about the realities of food animal production and the common management practices that are utilized within the beef industry such as castration. The value of boxed beef is what typically dictates the value of beef carcasses and beef carcass value is what typically determines live cattle price to a certain extent Therefore, implementing management strategies that do not compromise carcass merit and meat quality would potentially be valuable to continuation of beef production that yields consumer acceptable product and hopefull y lends itself to sa tisfactory monetary returns for the producers. Feed intake and efficiency are difficult to measure and often not reported in castration studies. M any of the decreases in performance observed in late castration studies are due to decreas ed feed and water intake and a subsequent numerically greater F:G New technologies allow for the measurement of these parameters on an i ndividual basis. Through technological advancements like the GrowSafe System ( GrowSafe Systems Ltd., Airdrie, Alberta, Canada) it is possible to monitor feed intake, water intake, individual feed efficiency, and feeding behavior all while being in a group fed pen Residual Feed I ntake Providing feed to animals is a major cost in all animal production systems. In extensive grazing systems the inclusion of supplemental feedstuffs remains a major cost, second only to fixed cost s (Herd et al., 2003). Efficiency of utilization of these supplements under grazing conditions is often unknown and on an individual basis is unknown in grain feeding conditions Variation between animals in converting feed

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33 supplements into body tissue is important in determining net income in beef production systems (Koch et al., 1963). Historically feed efficiency has been quantified through feed conv ersion ratio (FCR) however this can potentially be misleading in that a c alf that has decreased feed intake and decreased gain can have th e same FCR as a calf that has increased feed intake and increased gain Selecting for increased F CR can also lead to i ncreased mature BW in the cow herd, thus increasing nutritional requirements. M easuring feed efficiency is costly and difficult to quantify precisely in beef catt le (Herd et al., 2003). First proposed by Koch et al. (1963) is the concept of residual feed i ntake (RFI). Residual feed intake is the difference between the actual feed intake and the expected feed intake for a given body weight (BW) and growth rate. Residual feed intake is divergent of BW and growth rate (Herd and Arthur, 2009). Low (negative) RF I values are desirable, indicating that the animal consumed less feed than it was expected to for a certain body size and growth rate. Conversely, high (positive) RFI values are animals that consumed more feed than expected therefore being less efficient. Residual feed intake has been evaluated by many researchers with respect to the physiological basis (Herd and Arthur, 2009), genetic variation (Herd and Bishop, 2000), biological basis (Carstens and Kerley, 2009), and effect on meat quality (Baker et al., 2006). Recent research evaluating RFI through utilization of the Calan gate system (Herd and Bishop, 2000), and the GrowSafe feed intake system (Elzo et al., 2009) have studied efficiency through feeding pelleted forage based rations and concentrate diet s respectively. Although there have been relationships reported between RFI and production traits, the heritability of RFI remains unclear In order for the relationship

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34 between RFI to be advantageous to producers for use in selection there must be a mode rate level of heritability to make genetic progress Herd and Bishop (2000) report an estimate of RFI heritability at 0.16 in Hereford cattle which agrees with a recent study with crossbred cattle where heritability was estimated at 0.19 (Elzo et al., 200 9) Archer et al. (2002) reported a heritability estimate in Angus, Hereford, and Shorthorn cattle of 0.23. Arthur et al. (2001) indicated that the heritability of RFI in Angus cattle is 0.39. Utilization of the GrowSafe S ystem The GrowSafe system makes mo nitoring feed intake, water intake, and feeding behavior more simple Through the use of individual radio frequency identification (RFID), each animal is identified and when the animal approaches the feed/water bunk the RFID is recorded. The GrowSafe syste m measure s the amount of feed consumed through the difference of the amount present prior to the animal arriving at the bunk and the amount present after the animal leaves the bunk. The measurement of water intake is recorded the same way. The GrowSafe sys tem continuously monitors these feeding events throughout the day and night and records the time of day and amount consumed at each feeding event. GrowSafe technology also enables researchers to record the feeding behavior. This is accomplished through cap turing time of day, trips to the bunk within a day and head down feeding events within a trip to the bunk. Through this technological advancement there has been much research on effect of genotype, phenotype, and physiological variation on RFI (Herd and Bi shop, 2000; Elzo et al., 2009; Nkrumah et al., 2007a; Carstens and Kerley, 2009; Herd and Arthur, 2009) R esearch on the effect of variation in RFI on performance, reproduction, and carcass characteristics has been

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35 conducted (Castro Bulle et al., 2007; Bin gham et al., 2009; Herd and Bishop, 2000; Baker et al., 2006) However, very little research has been conducted in the area of how common animal husbandry practices can affect individual performance and RFI in beef calves. In the beef industry, management practices such as castration are necessary to produce the typ e of beef our consumers demand. This management practice can be successfully carried out through a variety of different techniques. However, t he method of castration could potentially have differ ent effects of beef calf performance and RFI The ability to select c astration methods that decrease the negative effect on calf performance and fe ed efficiency would be valuable to the beef industry. Genetic and Phenotypic B asis In young Hereford bulls it was reported that phenotypic and genetic variation does indeed exist in feed intake that is independent of body size a nd growth rate (Herd and Bishop, 2000). This r e search indicated that because of this variation it should be possible to implement selecti on to reduce feed intake without effecting BW and growth rate, the phenotypic variance associated with feed intake in this study was 20.56 kg Residual feed intake was genetically and phenotypi cally independent of ADG ( r = 0.09 0.29 and r = 0.01 0.05, respectively), mature cow weight also appeared to be genetically independent of RFI measured during a post w eaning performance test ( r = 0.09 0.26). Residual feed intake had high genetic and phenotypic correlations with bo th feed conversion ratio ( r = 0.70 0.22 and r = 0.61 0.03, respectively) and lean feed conversion ratio (feed intake/(weight gain predicted carcass lean content ) ; r = 0.72 0.18 and r = 0.63 0.03, respectively; Herd and Bishop, 2000). Thi s may potentially indicate that while s election for low RFI may not affect growth rate and body

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36 size it will segregate the more eff icient animals that eat less fro m those animals that are similar in body size and growth rate however consume increased amounts of feed Physiological B asis Herd et al. (2004) reported that there are likely to be at least 5 major physiological processes that can potentially explain variation in RFI. These processes are: 1) intake of feed; 2) digestion of feed (associated energy cost); 3) metabolism (anabolism and cat abolism associated with and including variation in body composition); 4) activity; and 5) thermoregulation. As feed intake increases the amount of energy expended to digest the feed increases, this amount of ene rgy expended is known as the heat increment o f feeding (HIF ). Knowing that selection for RFI is associated with inter animal variation in feed intake, animals that eat less, for the same level of performance, could be expected to have a lower HIF. Digestion of feedstuffs plays an important role in t he overall efficiency of an an imal. It is known that increased feed intake leads to increased ruminal passage rate which affects both the site and extent of digestion (Church, 1988) It may be that the increased intake by high RFI cattle decrease s the abso rption of nutrients and therefore limit their ability to meet maintenance requirements causing these cattle to have higher intakes for the same level of growth and body size. Differences in body composition may also contribute to the variation in RFI beca use lean tissue accretion requires less energy per unit of gain than fat (1.24 vs. 9.39 kcal/g; Carstens and Kerley, 2009). The differential in energy cost is due to a greater variation in protein turnover, than in fat gain. Any variation in composition of gain or the body can affect the apparent efficiency of nutrient utilization (Herd et al., 2004).

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37 Carstens and Kerley (2009) stated that energy expenditures associated with consuming feed are strongly related to the amount of time spent eating but not eat ing rate (feed consumed per unit time). Therefore, differences in time spent eating and frequency of meals consumed may contribute to the inter animal variation in RFI due to the activity related energy expenditures. The primary route for energy loss is e vaporative heat loss through respiration. However, no studies have investigated the eff ect of respiration rate on RFI. A b iological/physiological basis for RFI remains unclea r and more research is needed to segregate the mechanisms that contribute the most to this inter animal variation. However in studies that investigate these mechanisms in cattle divergently selected for low RFI indicate that the variation in function of these physiological mechanisms may be small and hard to detect (Herd and Arthur, 200 9) Feeding B ehavior There are many factors that can potentially affect efficiency of feed utilization in beef cattle. Lancaster et al. (2009) using Angus bulls (n = 341; initial BW = 371.1 + 50.8 kg) recieving a corn silage based diet through a GrowSafe fe ed intake facility, that low RFI bulls had significantly shorter meal duration (min/d) than medium and high RFI bulls, with medium RFI bulls being intermediate and different than both high and low RFI bulls (92.93, 99.25, and 107.24 min/d, respectively). M ea l frequency was significantly decreased for l ow and medium RFI bulls compared to high RFI bulls (7.28 and 7.64 vs. 8.17 events/d). In addition duration of time spent at the feed b unk with head down was significantly decreased for low RFI bulls compared to medium and high RFI bulls, with medium being intermediate and different than both low and high RFI bulls (41.99, 45.31, and 49.48 min/d, respectively). Meal eating rate was found to be

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38 similar for low, medium, and high RFI bulls. This would indicate tha t the more efficient bul ls did not feed as often and did not consume as much total feed as less efficient bulls. These results are in agreement with a study done by Nkrumah et al. (2007a) using steer calves sired by Angus, Charolais, and hybrid bul ls of si milar BW (353 + 61 kg). Conversely, in another study utilizing 115 Brangus heifers (236 + 10.7 d ays of age) being fed a roughage based diet through a Calan gate feeding facility, meal duration (219.6 vs. 219.9 min/d) and meal frequency (15.06 vs 14.75 eve nts/d) were similar for low and high RFI heifers. However, head down du ration was significantly greater for low vs. high RFI heifers (151.7 and 123.5 min/d, respectively ; Bingham et al., 2009 ) and meal eatin g rate was significantly decreased for low compar ed to high RFI heifers (41.7 vs. 49.5 g/min), indicating that the most efficient heifers spent more time feeding per day than the least efficient heifers. However, it was concluded that the lack of competition for feed in this experiment as a result of th e calan gate system, may have altered feeding b ehavior (Bingham et al., 2009). Golden et al. (2008) observed little differences in overall feeding behavior between low and high RFI feedlot cattle during two separ ate experiments. During Exp. 1 cattle were f ed a traditional feedlot ration containing roughage and during the second experiment cattle were fed a ration containing no roughage. The most significant observation in terms of feeding behavior was th at low RFI calves had significantly decreased eating b outs per day than did high RFI feedlot cattle in both experiments In Exp. 1, high R FI cattle ate 18.2 meals/d while low R FI cattle ate 11.0 meals/d In addition in Exp. 2 high RFI cattle ate 17.6 meals/d compared to low RFI cattle which

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39 ate 14.5 meals/d The authors reported that overall limited differences were observed in feeding behavior between low and high RFI feedlot cattle The results of these experiments indicate increased variability of feed intake per eating bout throughout the day for low RF I feedlot cattle. Gold en et al. (2008) did not report any differences in digestibility, rate of digestion or gastrointe stinal passage rate. Thiago et al (1992) re ported that frequency of feeding had no significant effect on digestibility between hay and s ilage diets however increased meals/d tended to remove the diurnal variation in rumen p H. Wales et al. (2004) hypothesized that decreasing the diur nal variation in ruminal pH would increase digestion of forages being grazed, when ruminal pH was low. Wales et al. (2004) found that maintaining a constant pH at approximately 6.1 did increase digestion of forages in a grazing situation when pH was low (5.6). Thiago et al. (1992) also reported that feeding frequency had no significant effect on passage rate. Th ese results indicate that variation in feeding events/ day may not have a physiological impact on digestion and absorption of feedstuffs. Carcass P arameters Previous studies have demonstrated that RFI has a minimal effect on carcass parameters (Baker et al. 2006; Castro Bulle et al., 2007; Cruz et al., 2010). However, Nkrumah et al. (2007b) reported that high RFI cattle had increased back fat thickness compared to their high RFI counterparts with medium RFI being intermediate and similar to low RFI cattle. Interestingly, in this experiment similar (P = 0.21) marbling scores were also observed among low, medium, and high RFI cattle. This work is in agreement with results published by Lancaster et al. ( 2009). These results indicate that selection for low RFI m ay be used to reduce feed intake and have little to no impact on

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40 carcass characteristics a nd quality, or selection for low RFI may decrease back fat thickness while maintaining adequate intramuscular f at and subsequent quality grade.

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41 CHAPTER 3 EFFECT OF C ASTRATION TECHNIQUE ON BEEF CALF PERFORMANCE RESIDUAL FEED INTAKE, AND INFLAMMATORY RESPONSE Introduction It is customary for cow/ calf operators to castrate male beef calves prior to weaning. However, some calves are not castrated until after weaning. Sev eral meth od s of castration are available and t he decision of which method to utilize may be a function of the type and size of the calf (Zweiacher et al., 1979). Larger and older calves have larger testicles and increased blood flow to the testes, causing the calf to be susceptible to increased blood loss. This blood loss can be eliminated if a bloodless means of castration is used. However these methods also have risk, and may be problematic in terms of anaerobic infect ions like tetanus Several studies ha ve demonstrated that male beef calves endure an observable degree of pain when castrated (Fisher et al., 1996; Ting et al., 2003) This pain increases in acuteness age, BW and testicular size increases (Chase et al., 1995; Staff ord et al., 2002) All methods of castration cause significant acute pa in and distress; however surgical castration is suggested to be more painful initially evidenced by increased plasma cortisol (Stafford et al., 2002). P ain and inflammation may also af fect the growth rate and efficien cy of beef calves (Fisher et al., 1997, Ratcliff et al., 2005 ) If specific methods of castration can be utilized to lessen the pain then theoreticall y growth rate and efficiency may be maximized. Several studies have docum ented decreased gains in castrated calves compared to intact male calves but there has been minimal research on the effect of castration on feed efficiency (Brazle, 1992; Faulkner et al., 199 2). There have been no studies investigating the effect of castra tion stress on residual feed intake (RFI) and whether

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42 variation in RFI exist s among calves castrated by different methods. There have also been no studies evaluating the effect of the Henderson Castrating Tool (Stone Manufacturing and Supply Co., Inc., Kan sas City, MO) on beef calf performance or feed efficiency. The objective of this experiment was to evaluate the rate of growth, feed i ntake, water intake, RFI, and inflammatory reaction of male beef calves in response to different methods of castration dur ing the feedlot phase. Materials and Methods Animals and Treatments Seventy five male Angus (n = 30) and Brangus (n = 45) calves (214 3.2 kg) were obtained from the University of Florida Santa Fe Beef Unit (Alachua, FL ). All procedures during this experi care and use committee (IACUC). C alves were weaned for seven d prior t o transport 349 km to the North Florida Research (NFREC) GrowSafe feed efficiency facility in Marianna Florida. Calves arrived at NFREC in a single semi load. The arrival date was 22 d prior to the initiation of the experiment A pre experimental period (acclimation period) began on d 21 and lasted until d 0 (day of castration). Calves were str atified by breed, age and weaning weight and randomly allocated to one of five treatments (n = 15 calves/treatment): 1) control steers (CON) were castrated surgically prior to weaning at an av erage age of 52 d (8 85 d) ; 2) intact bulls (BULL); 3) bulls ca strated by the Callicrate Bander (No Bull Enterprises, LLC, St. Francis, KS; BAN) ; 4) bulls castrated using the Henderson castration tool ( HEN; Stone Mfg & Supply Co., Kansas City, MO ) ; and 5) bulls castrated surgically (SUR) The e xperiment was comprised of two data collection periods, post castration p eriod (d 0

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43 14), and overall period (d 0 84). C alves wer e randomly assigned to one of five pens so that all treatments were equally represented in all pens C alves were vaccinated pre trial against IBR, B VD, BRSV, PI3 (Cattle Master Gold, Pfizer Animal Health), blackleg (Ultra Choice 7, Pfizer Animal Health), and treated for inter nal and external parasites ( Ivomec Epirnex Merial) Over the entire trial calves showing signs of respiratory disease were rec orded and treated with Draxxin (tulathromycin Pfizer Animal Health ) at label dose Sixteen percent (n = 12) of ca lves were treated for respiratory disease one time 11% of all calves (n = 7; 58% re treat) were re treated for respiratory disease and 1 cal f was treated a third time. These calves were treated across the first 4 wk of the experiment and after d 28 no cattle were treated during the remainder of the experiment The calves were offered a mixed diet (TDN = 67.3% and CP = 12.2%, DM = 89%) ad libit um. Calves assigned to the BAN, HEN and SUR treatments were castrated on d 0. Ca stration was performed by trained technicians under the supervision of a University of Florida v eterinarian. Castration was completed by the same technician in the same manner for each calf for each treatment group All calves on all treatments were vaccinated subcutaneously with 500 unit s of tetanus antitoxin on d 0. Banded calves were restrained in a chute, the band was applied around the scrotum proximal to the testes. The e lastic band was tightened by a ratcheting tool until adequate tension was applied, a metal grommet was then crimped around the band to ho ld tension and reduce blood to the scrotum and testes and subsequent sloughing of the scrotum and testes

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44 Henderson ca strated calves were restrained in a chute and castrated by incising the scrotum with a Newberry knife, leaving an anterior and posterior flap. Testes were then exposed and removed by the Henderson castrating tool. The castrating t ool was clamped on each s permatic cord individually and rotated by a cordless drill approxima tely 20 rot ations until the cords severed Surgically castrated calves were restrained in a chute and castrated by incising the scrotum with a Newberry knife, leaving an anterior and poste rior flap. Testes were then expose d and spermatic cords were crimped using an emasculator Sampling and Analysis Shrunk BW were obtained on d 0, 14, and 84. In addition full BW were recorded on d 7, 28, 42, 56, and 70. All cattle were weighed in the morni ng and at approximately the same time for each weigh date On days that shrunk BW were recorded access to fe ed and water was removed by 1900 h the previous evening Calves were individually weighed utilizing a Digistar dig ital scale. After each weigh dat e calves were returned to their respective pen immediately. F eed intake and water intake were recorded using the GrowSafe system Trips to the feed bunk and head down feeding events we re also recorded through utilizing radio frequency identification tags. Blood samples were collected from a sub sample of the cattle at the beginning of the experiment to investigate stress and inflammation resulting from castration Three pens (15 calves/pen) were sampled by blood collection via jugular venipuncture on d 0, 2, 6, 9, 12 and 15 Plasma was extracted from blood samples by centrifugation at 1,500 x g, was then stored at 20 C until analyzed for concentrations of ceruloplasmin and haptoglobin

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45 Plasma ceruloplasmin oxidase activity was measured in duplicate sampl es by using the colorimetric procedures described by Demetriou et al. (1974). The intraassay CV of duplicate samples was controlled to values of 10%. Ceruloplasmin concentrations were expressed as milligrams per deciliter, as described by King (1965). Int erassay variation of both acute phase protein assays were controlled by CV limits of 10%, as a result of a control sample analyzed in duplicate within each individual assay run. When the interassay CV exceeded 10%, all samples contained in the individual run with the control sample exceeding the average by the greatest were reanalyzed. This step was repeated until the results of standard pools for all runs resulted in a CV of 10% ( inter assay variation = 5.13 %; intra assay CV variation = 3.05 %). Plasma haptoglobin concentrations were determined in duplicate samples by measuring haptoglobin hemoglobin complexing by the estimation of differences in peroxidase activity (Makimura and Suzuki, 1982). Results are expressed as arbitrary units resulting from the absorption reading x 100 at 450 nm. For samples with an absorption reading of 0.010, the intraassay CV of duplicate samples was controlled to values of 20%, and for samples with an absorption reading of 0.010, the intraassay CV of duplicate samples was controlled to values of 10% ( inter assy variation = 5.46 %; intra assay CV va riation = 3.37 %; Hepburn et al., 2009) Data were analyzed by the MIXED procedure of SAS 9.2 (SAS Inst. Inc., Cary, NC). The model included the main effects of treatment, breed, day All variables quantified by day or by week were analyzed using repeated m easures. Least square means are reported with standard errors, means were separated for comparison by PDIFF. All variables with P values of 0.05 were reported as differences, all variables

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46 with P values between 0.05 and 0.10 were reported as tendencies and anything greater than 0.10 was considered non significant. All two way interactions found to be significant at P < 0.10 for a particular variable were included in the model for that variable. Results and Discussion Average Daily Gain Average daily gain (ADG) during the post castration period ( d 0 to 14 ) tended (P = 0.06) to be affected by treatment (Figure 3 1). All castrated calves gained les s (P < 0.05) than CON with BULL being i ntermediate and similar (P = 0.23 ) to other treatments. Angus and Bra ngus calves had similar (P = 0.19 ) AD G during the post castration period (Figure 3 2). Average daily gain over the entire experiment ( d 0 to 84 ) was similar (P = 0.4 0 ) for all treatment groups (Figure 3 3) indicating that castrated calves were able to compensate and recover from castration regardless of castration method Angus calves (P = 0.06) had greater ADG than Brang us calves from d 0 to 84 ( 0.94 vs. 0.84 kg/d ; Figure 3 4 ) Our results indicate that all methods of castration reduce ADG compared to contr ol steers during the first 14 days after castration but by d 84 ADG was similar regardless of castration technique. These results imply that m ethod of castration does not impact ADG long term. A study b y Lents et al. (2006) indicated that calves bande d or surgically castrated at 2 to 3 mo of age gain differently from t ime of castration to weaning (2 to 3 mo to 7 to 8 mo of age ) Calves banded at 2 to 3 mo of age had increased (P < 0.05 ) ADG pre weaning compared to ca lves surgically castrated at 2 to 3 mo of age and intact male calves gained similarly (P > 0.05) to both castration methods pre weaning (0.94, 0.90, and 0.91

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47 kg/d, respectively) Howe ver, 50 days post weaning no difference (P > 0.05) was observed between calves bande d or surgic ally castrated at 2 to 3 mo of age (0.49 and 0.48 kg/d, respectively). C alves banded at weaning gained less (P < 0.05) than both calves banded and surgic ally cas trated at 2 to 3 mo of age (0.43 vs. 0.49 and 0.48 kg/d, respectively) no control treatment was present in the post weaning period ( Lents et al., 2006). Thi s study differed from the current experiment with respect to age and weight at the time of castrati on. In the current experiment calves were weaned prior to castration. This may indicate that method is not as imp ortant as timing of castration. When bulls (300 kg) of unknown age, origin, and breed were used to evaluate the effect of castration on perform ance. Purchased steers gained faster (P < 0.05) in a 110 d post castration st udy compared to banded bulls wit h surgically castrated bulls being intermediate and similar to both groups (Brazle, 1992). In another experiment utilizing calves (115 kg) of unkno wn age, origin, and breed purchased in Southeastern sale barns, Brazle (1992) observed that in a 33 d post castration period calves purchased as steers gained faster (P < 0.05) compared to surgically castrated and banded calves. Surgical and banding castra tion treatments gained similarly over the 33 d trial. In agreement with the current study it appears that method is not as important as castration timing and BW of calves at castration. In addition with heavier cattle, banding may not be as non invasive a nd short term in pain response as initially believed Average daily gain wa s evaluated by period from d 7 to 70 (Figure 3 5). It appears that ADG from d 7 to 28 is affected by method of castration. However, ADG d 28 to 42, d 42 to 56 and d 56 to 70 was si milar regardless of castration method, indicating that at some point after d 28 and before d 42 all treatments began to gain similarly. Average

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48 daily gain was evaluated fro m d 7 to 28 (un shrunk BW ; Figure 3 6 ). ADG was affected (P = 0.001) by treat ment d 7 to 28. BAN calves gained less (P < 0.05) d 7 to 28 compared to CON, BULL, HEN, and SUR Castration method may not be as important from a growth rate standpoint in the long term; however there was a delayed suppression of gain in BAN calves during the ea rly post castration period Ratcliff et al. (2005) reported that weaned beef calves (210 14.5 kg) castrated surgically tend to gain more (P < 0.1 0 ) t han banded calves in the 50 d after castration, ho wever no controls were pres ent This indicate s that t he re was a difference in the duration of decreased performance associated with different methods of castration, however in the long term all castration and control treatments were gaining similarly at d 42 and after. Feed Intake Daily f eed i ntake from d 0 to 14 ( post castration period) was similar (P = 0.76) for treatment groups (F igure 3 7 ) An interaction (P = 0.03) between treatment and day was detected for daily fe ed intake d 0 to 14 (Figure 3 8 ). Henderson castrated calves consumed less (P < 0.05) than C ON, BULL and BAN on d 0 and tended to eat less (P = 0.1) feed than CON on d 2 ; however ate similarly to SUR on both days BAN calves tended to consume less (P = 0.1) feed than both CON and SUR calves on d 10 and BULL and CON calves on d 14. These results would indicate that there is some loss of appetite as a result of surgical castration early post castration evidenced by HEN e ating less than CON early post castration ; however this is not supported by SUR as they were intermediate a nd similar to both CO N and HEN. It appears that early post castration t here may be a difference in feed intake of calves castrated with emasculators versus Henderson castrating tool, however no clear trend was observed It is apparent that there is a delayed effect of banding on daily feed

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49 intake manifesting itself by a clear decrease in feed intake on d 10 and 14 the duration of this lag in feed intake is unknown D ec reased intake post castration may be a funct ion of i ncreased pain and inflammation. Ch ase et al. (1995) indica ted that the lag could exist until d 24 to 28 in calves banded with large latex bands compared to surgically castrated calves. Angus calves had decreased (P = 0.007 ; Figure 3 9 ) average daily feed intake compared to Brangus calves during the post castratio n period (5.1 vs 6.4 kg/d) An interaction (P = 0.03) between breed and day was detected for daily feed intake d 0 tp 14 (data not shown ) There was a trend indicating Angus calves consumed less (P < 0.05) feed than Brangus calves on d 0, 1, 4, 7, 8, 9, 1 0, 11, 12 and 14. Mader et al. (2006) suggested that hot, humid conditions with intense solar radiation coupled with low wind speed can increase animal heat load, resulting in reduced performance, decreased animal comfort, and death. Feed intake is decreas ed in hot weather, the temperature at which Bos taurus cattle begin to consume less feed and sacrifice performance is 25 C if protected from solar radiation (H ahn, 1995). In the current experiment cattle were housed in a n open a ir barn and ambient temper atures exceeded the threshold for environmental stress in Bos taurus cattle described by Hahn (1995) During the post castration period, all days were at or above 25 C (Figure 3 20), suggesting Angus steers may have been experiencing increased heat stress and a subsequent loss of appetite. Feed intake over the entire trial (d 0 to 84 ) was analyzed by week (12 wk ). Mean weekly f eed intake ( 1 to 12 ) was not impacted by treatment (P = 0.92 ; Figure 3 10 ). An interaction (P = 0.05) between treatment and week was detec ted for feed intake (Figure

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50 3 11 ) BAN calves tended to have decreased (P < 0.1 0 ) weekly fee d intake compared to CON in wk 2, HEN i n wk 4 and BULL in w k 11. CON, BULL, HEN and SUR calves had similar weekly feed intake throughout the entire trial. The se results support our gain data and suggest that BAN calves may have a delayed stress response resulting in decreas ed feed intake. Others have found that castrated calves tend to eat less (P < 0.05) than intact male calves early post castration and simila r 28 d post castration (Fisher et al., 1997). There is little data available with respect to individual calf feed intake as it relates to met hod of castration Feed intake was not impacted by breed over the entire 84 d experiment (P = 0.31). However, a bre ed x week interaction (P = 0.04) was detected for feed intake wk 1 12 (Fig ure 3 12 ) Angus calves consumed less (P < 0.05) feed than Brangus calves in wk 2 and 3 and tended to consume less (P < 0.1 0 ) f eed than Brangus calves in wk 4 and 5. Angus and Bran gus calves consumed similar (P = 0.97) amounts of feed in wk 1, 6, 7, 8, 9, 10, 11 and 12 Historical climatic data was collected and evaluated f or th e entire experiment (Figure 3 13 ). The decreas ed feed intake observed in wk 2, 3, 4, and 5 may have been d ue to the high ambient temperature When feed intake was evaluated as a % of BW d 0 to 14 (data not shown) and d 0 to 84 (Figure 3 14) t reatment had no impact (P = 0.75) B reed did not impact (P > 0.1 0 ) feed intake as a % of BW from d 0 to 14 (data not sh own) However An gus calves consumed a greater (P = 0.04) a mount of feed as a % of BW over the entire trial ( d 0 to 84 ; Figure 3 15) Earlier analyses indicated that there was a difference in absolute feed consumption between breeds with Brangus consuming the most However, t hese results indicate that Angus calves were actually consuming more feed This

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51 pheno menon is a function of the variation observed in feed consumption be tween calves of differing BW Brangus calves had increas ed (P = 0.0004) average BW d 0 to 84 compared to Angus calves (270 5 kg and 242 6 kg, respectively). On an as fed basis Brangus were reported to have consumed more feed however this is what would be expected from heavier calves regardless of breed. Feeding beh avior was not impac ted (P = 0.34 ) by treatment early post castration (Figure 3 16) There was a trend for all treatments to have decreased trips to the bunk on d 1 and 0. This is attributed to the shrink period on d 1 and the time spent out of the pen while being processed on d 0. On d 1, 0, 1, and 2 all treatments had similar number of trips to the feed bunk. These results indicate that not only was weekly feed intake n ot altered by castration method, but fe eding behavior was not impacted by the stress of castration early post castration. Water Intake Water intake was similar (P = 0.38) amon g treatment groups from d 0 to 14 (data not shown) An interaction (P = 0.005) between treatment and day wa s detected for water intake d 0 to 14 but no clear trends were evident (Figur e 3 17 ). Angus calves had a decreased (P < 0.0001) average daily water intake during the post castration period compared to Brangus calves (38.3 vs. 44.9 L/d, respectively). An interaction (P = 0.03) between breed and treatment wa s detected for mean water intake d 0 to 14 (Figure 3 18 ). Angus CON, BAN, HEN, and SUR calves consumed more (P < 0.05) water than all Brangus treatments d 0 to 14. However, Angus BULL consumed more (P < 0.05) water than Brangus BULL and HEN but consumed similar (P > 0.1 0 ) amounts o f water compared to Brangus CON, BAN, and SUR.

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52 An interaction (P < 0.0001) between breed and day was detected for water intake during the post castration period (Figure 3 19 ) Ang us calves drank more (P < 0.05 ) water than Brangus calves on d 1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14. On d 0 Angus calves consumed similar ( P > 0.1 0 ) amounts of water compared to Br angus calves. Similar to feed intake, t hese results suggest that ambient temperature potentially played an important role in driving the differe nces in water consumption between Angus and Brangus calves. The highes t average day t ime temperatures of the entire 12 wk trial were observed over the first 14 d ( mean = 26 C ; Figure 3 20 ). Over the entire experiment w ater intake was not impacted (P = 0. 72) by treatment d 0 84 (Figure 3 21 ) Angus calves consumed increased (P < 0.0001) amounts of water compared to Brangus calves d 0 to 84 (data not shown) An interaction (P < 0.0001) between breed and week was detected for water intake d 0 to 84 (Figure 3 22 ) Angus calves consumed more (P < 0.05) water than Brangus calves during wk 1 to 11, and tended to consume more (P = 0.06) water compar ed to Brangus calves during wk 12. The mean ambient day time and night time temperature s during the current trial were 22 and 10C, respectively. Lofgreen et al. (1975) suggested that there is a greater heat tolerance in Bos indicus cattle compared to Bos taurus Hansen et al. (2007) documented that in Florida, as Brahman percentage increased water consumption decreas ed linearly. Winchester and Morris (1956) suggests that the rate of water consumption for Bos Taurus and Bos indicus cattle is similar between ambient temperatures of 12 and 4 C but diverges at temperatures above this range This may indicate that the hi gh ambient temperatur es observed in the current experiment induced

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53 variation in water consump tion between the two breed types but high temperature does not appear to be the sole factor driving water consumption. It is known that increased dry feed intake i s accompanied by increased water intake in growing cattle (Meyer et al., 2006) In the current trial Angus calves consumed more feed d 0 to 84 (% of BW ) compared to Brangus calves The increased water consumption by Angus calves may be a result of the inc reased feed consumpt ion coupled with high ambient temperature. Feed Efficiency Gain to feed ratio was similar among treatments d 0 to 14 (P = 0.28 ; Figure 3 23 ) and d 0 to 84 ( P = 0.32; Figure 3 24 ). Angus calves were similar (P = 0.25 ) to Brangus calves i n G:F d 0 to 14 (Figure 3 25 ), but had increased (P = 0.002) G:F compared to their Brangus co unterparts over the 84 d trial (Figure 3 26 ). These results indicate that over the entire trial Angus calves were slightly more efficient than Brangus calves. Thi s increased efficiency observed in A ngus calves d 0 to 84 could pote ntially be due to the tendency for Angus to gain more than Brangus d 0 to 84, coupled with the decreased absolute feed intak e observed in Angus calves d 0 to 84. Our results agree w ith ano ther study that indicated calves with higher Brahman percentage were less efficient in terms of feed conv ersion ratio (Elzo et al. 2009) Residual feed intake (RFI) tended to be affected (P = 0.1 0 ) by treatme nt during the post castration period (Figure 3 2 7 ) Control steers and BULL were similar (P > 0.1 0 ) in RFI value, but lower (P < 0.05) than SUR BAN and HEN were intermediate and similar ( P > 0.1 0 ) to CON, BULL, and SUR. These results suggest that castration did induce a change in efficiency as measured by RFI early post castration. There is a clear trend showing that castration increased RFI, but the magnitude is small and short in duration.

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54 Angus and Brangus calves had similar (P = 0.98 ; data not shown ) RFI valu es during the post castration period Elz o et al. (2009) documented that calves were increasingly efficient measured by RFI as Brahman percentage increased in terms of RFI. In another study, Hansen et al. (2007) suggested that there is a linear trend indicating RFI decreases (efficiency improves) as Brahman percentage increases but the comparison of RFI between Angus and Brangus was not as clear. Over the 84 d experiment r esidual feed intake was not affected (P = 0.85) by treatment or breed (P = 0.85 and P = 0.93, respectively ; Fig ure 3.28 ) sugg esting that in the long term, castration does not negatively impact efficiency as measured by RFI long term. Our data indicates that the impact of castration observed early post castration is mitigated in the long term. There are no reports thus far of stu dies evaluating the impact of common animal husbandry practices such as ca stration on RFI, the current trial may prove that castration can be accomplished by any method without sacrificing long term feedlot performance. Acute Phase Proteins Plas ma concentr ation of ceruloplasmin te nded to be different (P = 0.10 ) among treatme nts post castration CON had decreased (P < 0.05 ) plasma ceruloplasmin concentration c ompared to BULL and HEN post castration and tended to have decreased (P < 0.10 ) plasma ceruloplasmin concentration compared to SUR. BULL, BAN, HEN, and SUR had similar (P > 0.1 0 ) plasma ceruloplasmin concentration post castration suggesting that castration does elicit an inflammatory response compared to contro l steers. However, in the current trial, no one method induced a higher level of inflammation early post castration. These results may be important fr om an animal

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55 welfare standpoint, there are minimal differences among castration methods and only slight differ ences compared to CON An interaction ( P = 0.02) was detected between treatm ent and day for plasma ceruloplasmin concentration post castration (Figure 3 29 ). All treatments had similar (P > 0.1 0 ) plasma ceruloplasmin concentration on d 0. CON had decreased (P < 0.05) plasma ceruloplasmin concen tration compared to BULL and HEN on d 2; BULL, HEN, and SUR on d 6 and 9; and tended (P < 0.1 0 ) to be lower than BULL, HEN, and SUR on d 12; and BULL, BAN, and SUR on d 15. Th e delayed increase in plasma ceruloplasmin concentration in BAN as compared to CO N suggests tha t banding induces a delayed inflammation response compared to surgical methods of castration. The increased plasma ceruloplasmin concentration levels HEN and SUR exhibit ed compared to CON indic ates that there is an acute inflammatory response early post castration in surgically castrated calves, however it is decreased over time. HEN and SUR were similar (P > 0.1 0 ) post castration indicating that su rgical castration induces a n inflammation response compared to CON but neither surgical method ( HEN and SUR) caused more inflammation than the other and by d 15 it is evident that all castration methods are similar. The effect of sex class (intact male calves vs. castrated male calves) on acute phase protein levels in calves exposed to a stressor re mains unclear. Qiu et al. (2007) reported that heifers had greater (P < 0.001) plasma ceruloplasmin concentration compared to steers post weaning and transportation, however sex was not important (P = 0.31) for other acute phase protein concentrations (fib rinogen and haptoglobin) investigated in the same study. In the same study it was hypothesized that breed of calf

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56 plays a role in acute phase prote in resp onse to stressor. I n the current experiment breed did not a ffect plasma ceruloplasmin concentration po st castration (P = 0.19; Figure 3 30 ). In the first 2 weeks post castration, t hese results indicate that inflammation is present early post castration regardless of the surgical method and a de layed inflammatory response is observed when calves are banded. Pl asma concentration of haptoglobin were similar (P = 0.16) among treatments. However, CON had the numerical lowest plasma haptoglobin concentration compared to BULL, BAN, HEN and SUR. An interaction (P = 0.0002) was detected b etween treatment and day for plasma haptoglobin concentration post castration (Figure 3 31 ) On d 2 CON had decreased (P < 0.05) plasma haptoglobin concentration compared to BULL, HEN and SUR. BULL a lso had decreased (P = 0.05) plasma haptoglobin concentration compared to HEN and SUR on d 2 indicating an inflammatory response in the two surgical castration methods Additionally, BAN had decreased (P = 0.002) plasma haptoglobin concentration compared to HEN and SUR on d 2 suggesting that the acute phase protein response in BAN was de layed CON had decreased (P < 0.05) plasma haptoglobin concentration compared to BULL on d 6 and 9. On d 6 CON had decreased (P = 0.04) plasma haptoglobin concentration compared to HEN and tended to have decreased (P = 0.06) plasma haptoglobin concentratio n compared to SUR. On d 15 BAN had increased (P < 0.05) plasma haptoglobin concentration compared to CON and BULL and tended to have increased (P < 0.1 0 ) Plasma haptoglobin concentration compared to HEN and SUR. These data suggest that plasma haptoglobin c oncentration was greater in the surgical methods early post castration but was not different from control steers by d 9. Calves that were banded responded like controls

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57 until d 15 when BA N had greater plasma haptoglobin concentration than CON and calves ca strated surgically indicating the delayed inflammatory response associated with banding calves. The driving factor behind the greater plasma haptoglobin concentration observed in intact male calves in the current study remains to be elucidated. Breed did not i mpa ct plasma haptoglobin concentration (P = 0.11; Figure 3 32 ) post castration contrary to some other research (Qiu et al., 2007) An interaction (P = 0.07) was detected between breed and day for plasma haptoglobin concentration (Figure 3 33 ) Angus c al ves had increased (P = 0.03) plasma haptoglobin concentration compared to Brangus calves on d 0 and tended to have increased (P = 0.06) plasma haptoglobin concentration compared to Brangus calves on d 6. On d 2, 9, 12 an d 15 breed did not impact plasma h aptoglobin concentration concentration (P 0.36). Our r esults indicate that overall the inflammatory response to castration was similar between breed post castration. Howeve r, it is evident by the breed* day interactio n that Angus calves had a greater inflammatory response to castration through d 6, but were similar to Brangus calves by d 9. Implications Male beef calve s are routinely castrated prior to leaving the cow calf operation or certainly before entering a stocker or feedlot environment. When managing weaned beef cal ves early post castratio n in sub tropical environments, our data would suggest that ADG is impacted for a period of less than 42 d post castration Surgical methods elicit more of an acute negative impact while ba nding resulted in a delayed suppression of gain nonetheless 42 d p ost castration all calves gain ed similarly regardless of castration method Feed intake was not different early post castration among treatment

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58 groups ; however there was some evidence suggesting that BAN calves endured delayed suppression of intake. Feed intake over the entire trial was not affected by castration method. Water intake was observed to be different among treatments on certain days early post castration although water intake overall was not impacted by castration method. Feed efficiency, meas ured as G:F or RFI wa s not impacted in the long term by castration technique. Acute phase proteins were ev aluated as a measure of inflammation. Early post castration it was evident that both types of surgical castra tion elicited a significant inflammatory response, this pain response was mediated by d 6. The acute phase protein response by d 15 was similar in all castration treatments, however banded calves were trending upwards indicating that there was a delayed response to castration by banding. Early p ost castration Angus and Brangus calves gained similarly, however over the entire trial there was a tendency for Angus calves to gain slightly mo re per day than Brangus calves There was an observable suppression in absolute feed intake for Angus calves ea rly post castration T his decrease was potentially due to the increased ambient temperature during that time period. Interestingly, Angus calves had increased feed consumption on a percentage of BW basis over the entire trial. Breed played a role in water intake during the trial T his is thought to have been a function of Angus calves drinking significantly more water due to the high ambient tempera tures. Castration should be carried out as early as possible, the method a producer chooses to utilize may no t be as important as the age and weight they choose to

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59 castrate their calves. In all measures observed in this study including stress and performance steers previously castrated prior to weaning were preferable to late castrates. If calves are castrated p re weaning the impact that the stress of castration will have on growth rate, feed intake, water intake, and feed efficiency is minimized

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60 Figure 3 1. Effect of castration technique on average daily g ain d 0 14. Treatment effect: P = 0.06. a, b M eans with different superscripts differ P < 0.05. Figure 3 2. Effect of bree d on average daily gain d 0 14. Breed effect: P = 0.2. ab b b b

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61 Figure 3 3. Effect of castration technique on average daily g ain d 0 84. Treatment effect: P = 0.40. Figure 3 4. Effect of breed on average daily g ain d 0 84. Breed effect: P = 0.06. x, y Means with different superscripts differ P < 0.1 x y

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62 Figure 3 5. Effect of castration technique on ADG d 7 70 by period. Figure 3 6. Effect of castration technique on A DG d 7 28. Treatment effect: P = 0.001. a, b Means with different superscripts differ P < 0.05.

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63 Figure 3 7 Effect of castration technique on daily feed int ake d 0 14. Treatment effect: P = 0.76. Figure 3 8 Effect of the treatment*day interacti on on daily feed int ake d 0 14. Treatment*Day: P = 0.03.

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64 Figure 3 9 Effect of breed on daily feed int ake d 0 14. Breed effect: P = 0.007. a, b Means with different superscripts differ P < 0.05. Figure 3 10 Effect of castration technique on w eekly f eed intake d 0 84. Treatment effect: P = 0.92. a b

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65 Figure 3 11 Effect of treatment*week interaction on weekly feed intake d 0 84. Treatment*Week: P = 0.05. Figure 3 12 Effec t of breed*week interaction on weekly feed intake d 0 84. B reed*Week: P = 0.04 Means differ P < 0.05, ** Means differ P < 0.1. *

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66 Figure 3 13. Average weekly ambient temperature readings for Marianna, FL d 0 84. Figure 3 14. Effect of castration technique on average daily feed intake as a percentage of BW on an as fed basis d 0 84. Treatment effect: P = 0.75.

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67 Figure 3 15. Effect of breed on average daily feed intake as a percentage of BW on an as fed basis d 0 84. Breed effect: P = 0.04. a, b Means with different superscripts differ P < 0.05. Figure 3 16. Effect of castration technique on feeding behavior early post castration. Treatment effect: P = 0.34 a b

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68 Figure 3 17 Effect of the treatment*day interaction on water int ake d 0 14. Treatment*Day: P = 0.005. Figure 3 18 Effect of the br eed*treatment interaction on daily water int ake d 0 14. Breed*Treatment: P = 0.03. a,b Means with different superscripts differ P < 0.05.

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69 Figure 3 19 Effect of the breed*day interaction on daily water int ake d 0 14. Breed*Day: P < 0.0001. Means d iffer P < 0.05. Figure 3 20. Daily ambient temperature d 0 14 in Marianna, FL.

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70 Figure 3 21. Effect of castration technique on weekly water intake d 0 84. Treatment effect: P = 0.72. Figure 3 22. Effect of the breed*week interaction on weekl y water intake d 0 84. Breed*Week: P < 0.0001. Means differ P < 0.05, ** Means differ P < 0.1.

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71 Figure 3 23. Effect of castration technique on G:F ratio d 0 14. Treatment effect: P = 0.28. Figure 3 24 Effect of castration technique on G:F rati o d 0 84. Treatment effect: P = 0.42.

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72 Figure 3 25. Effect of breed on G:F ratio d 0 14. Breed effect: P = 0.25. Figure 3 26 Effect of breed on G:F ratio d 0 84. Breed effect: P = 0. 002. a, b Means with differen t superscripts differ P < 0.05 a b

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73 Figure 3 27 Effect of castration technique on RFI d 0 14. Treatment effect: P = 0.1. a, b Means with different superscripts differ P < 0.05. Figure 3 28 Effect of castration techni que on RFI d 0 84. Treatment effect: P = 0.93.

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74 Figure 3 29 Effect of the treatment*day interact ion on plasma ceruloplasmin concentration post castration. Treatment*Day: P = 0.02. Figure 3 30 Effect of b reed on plasma ceruloplasmin concentration post castration Breed effect: P = 0.19.

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75 Figure 3 31 Effect of the treatment*day inter action on plasma haptoglobin concentration post castration. Treatment*Day: P = 0.0002. Figure 3 32 Effect of breed on plasma haptoglobin concentration post castration. Breed effect: P = 0.11.

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76 Figure 3 33 Effect of the bre ed*day inter action on plasma haptoglobin concentration post castration. Breed*Day: P = 0.07. Means differ P < 0.05, ** Means differ P < 0.1.

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77 APPENDIX DIET COMPOSITION Table A 1. Ration composition Ingredient Ration Corn 32.3 Soy bean hull and corn g luten feed mix 40.5 Molasses 2.9 Hay 22.7 Minerals 0.7 Salt 0.7 Table A 2. Nutrient composition Average Moisture 11.00 DM % 89.00 CP % 12.20 Available P % 11.60 ADICP % 0.60 ADJ CP % 12.20 ADF % 25.03 NDF % 46.57 TDN % 67.33 NEL, Mcal /lb 0.71 NEM, Mcal/lb 0.69 NEG, Mcal/lb 0.42 Ca % 0.46 P % 0.42 Mg % 0.24 K % 1.15 Na % 0.44 Fe ppm 313.00 Zn ppm 84.00 Cu ppm 24.33 Mn ppm 98.00 Mb ppm 0.43 S % 0.23

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78 LIST OF REFERENCES AccuWeather Inc. Weather data for Marianna, FL for S eptember 30, 2009 through December 23, 2010. http://www.accuweather.com Accessed April 10, 2010 Adams, T. E. and B. M. Adams. 1992. Feedlot performances of steers and bulls actively immunized against gonadotrop in releasing hormone. J. Anim. Sci. 70:1691 1698. Anderson, N. 2007. Castration of calves: Fact sheet. http://www.omafra.gov.on.ca/english/livestock/beef/facts/07 029.htm Accessed May 12, 2010. Arthur, P. F., J. A. Archer, D. J. Johnston, R. M. Herd, E. C. Richardson, and P. F. Parnell. 2001. Genetic and phenotypic variance and covariance components for feed intake, feed efficiency, and other post weaning traits in Angus cattle. J. Anim. Sci. 79:2805 2811. Archer, J. A., A. Reverter, R. M. Herd, D. J. Johnston, and P. F. Arthur. 2002. Genetic variation in feed intake and efficiency of mature beef cows and relationships with postweaning measurements. Proc. 7 th World Congr. Genet. Appl. Livest. Prod. 10. Baker, S.D., J.I. Szasz, T.A. Klein, P.S. Kuber, C.W. Hunt, J.B. Glaze, Jr., D. Falk, R. Richard, J.C. Miller, R.A. Battaglia and R.A. Hill. 2006. Residual feed intake of purebred Angus steers: Effects on meat quality and p alatability. J. Anim. Sci. 84:938 945. Bingham, G.M., T.H. Friend, P.A. Lancaster, and G.E. Carstens. 2009. Relationship between feeding behavior and residual feed intake in growing Brangus heifers. J. Anim. Sci. 87:2685 2689. Brazle, F.K. 1992. Effect of castration method on stocker health and gain. Kansas State University Report of Progress 651, Agriculture Experiment Station. Bruns, K.W. and R.H. Pritchard. 2004. Impact of castration time and method on carcass and palatability traits in steers. Sout h Dakota State University Beef Report, Department of Animal and Range Sciences. Capucille, D.J., M.H. Poore, and G.M. Rogers. 2002. Castration in c attle: Techniques and animal welfare issues. http://www.vetlearn.com A ccessed May 27, 2009. Carstens, G.E. and M.S. Kerley. 2009. Biological basis for variation in energetic efficiency of beef cattle. Page 124 in Proc. of the Beef improvement Federation 41 st Annual Research Symposium. Sacromento, California Castro Bulle, F.C.P., P.V. Paulino, A.C. Sanches, and R.D. Sainz. 2007. Growth, carcass quality, and protein and energy metabolism in beef cattle with different growth potentials and residual feed intakes. J. Anim. Sci. 85:928 936.

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79 Champagne, J.R., J.W. Carpenter, J.F. Hentges, Jr., A.Z. Palmer, and M. Koger. 1969. Feedlot Performance and carcass characteristics of young bulls and steers castrated at four ages. J. Anim. Sci. 29:887 890. Chase, C.C, Jr., R.E. Larsen, R.D. Randel, A.C. Hammond, and E.L. Adams. 1995. Pl asma cortisol and white blood cell responses in different breeds of bulls: a comparison of two methods of castration. J. Anim. Sci. 73:975 980. Church, D. C. 1988. Ruminal fermentation. Page 146 147 in The ruminant animal: digestive physiology and nutrtit ion Waveland press, Inc. Cruz, G.D., J.A. Rodriguez Sanchez, J.W. Oltjen, and R.D. Sainz. 2010. Performance, residual feed intake, digestibility, carcass traits, and profitability of Angus Hereford steers housed in individual or group pens. J. Anim. Sci. 88:324 329. Demetriou, J.A., P.A, Drewes and J.B. Gin. 1974. Ceruloplasmin. Pages 857 864 in Clinical Chemistry. D.C. Cannon, and J.W. Winkelman, ed. Harper and Row, Hagerstown, MD. Elzo, M.A., D.G. Riley, G.R. Hansen, D.D. Johnson, R.O. Meyer, S.W. Col eman, C.C. Chase, J.G. Wasdin and J.D. Driver. 2009. Effect of breed composition on phenotypic residual feed intake and growth in Angus, Brahman, and Angus x Brahman crossbred cattle J. Anim. Sci. 87:3877 3886. Erickson, H. H. 1984. Animal Pain. J. Appl. Physiol.56:1135 1136. Faulkner, D.B., T. Eurell, W. J. Tranquilli, R. S. Ott, M. W. Ohl, G. F. Cmarik, and G. Zinn. 1992. Performance and health of weanling bulls after butorphanol and xylazine administration at castration. J. Anim. Sci. 70:2970 2974. F ield, R.A. 1971. Effect of castration on meat quality and quantity. J. Anim. Sci. 32:849 858. Fisher, A.D., M.A. Crowe, M.E. Alonso de la Varga, and W.J. Enright. 1996. Effect of castration method and the provision of local anesthesia on plasma cortisol, scrotal circumference, growth, and feed intake of bull calves. J. Anim. Sci. 74:2336 2343. J. Enright. 1997. Effects of cortisol on in vitro interferon gamma p roduction, acute phase proteins, growth, and feed intake in a calf castration model. J. Anim. Sci. 75:1041 1047. Fisher, A.D., T.W. Knight, G.P. Cosgrove, A.F. Death, C.B. Anderson, D.M. Duganzich, and L.R. Matthews. 2001. Effects of surgical or banding c astration on stress responses and behaviour of bulls. Aust. Vet. J. 79:279 284.

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80 Golden, J.W., M.S. Kerley, and W.H. Kolath. 2008. The relationship of feeding behavior to residual feed intake in crossbred Angus steers fed traditional and no roughage diets. J. Anim. Sci. 86:180 186. Gwartney, B. L., C. R. Calkins, R. J. Rasby, R. A. Stock, B. A. Vieselmeyer, and J. A. Gosey. 1996. Use of expected progeny differences in beef: II. Carcass and palatability traits. J. Anim. Sci. 74:1014 1022. Hahn, G. L. 1995. Environmental influences on feed intake and performance of feedlot cattle. Pages 207 225 in Proc. Symp. Intake by Feedlot Cattle, F. N. Owens, ed. Oklahoma State Univ., Stillwater. Hansen, G.R., M.A. Elzo, D.G. Riley, S.W. Coleman and J.C. Paschal. 2007. Growth and feed efficiency: Utilization of bos indicus cattle in Florida beef enterprises. Proceedings 46 th Annual Beef Cattle Short Course. Gainesville, FL. p. 47 69. Heaton, K., D.R. ZoBell, and D. Cor nforth. 2004 Effects of delayed castration of Brit ish cross bred beef cattle on weight gain, carcass traits, and consumer acceptability. Page 130 in Proc.Wester n Sec., American Soc. Anim. Sci. Hepburn, J.J., J.D. Arthington, S.L. Hansen, J.W. Spears and M.D. Knutson. 2009. Technical note: Copper chaperon e for copper, zinc superoxide dismutase: A potential biomarker for copper status in cattle. J. Anim. Sci. 87:4161 4166. Herd, R.M. and P.F. Arthur. 2009. Physiological basis for residual feed intake. J. Anim. Sci. 87:E64 E71. Herd, R.M., J.A. Archer and P.F. Arthur. 2003. Reducing the cost of beef production through genetic improvement in residual feed intake: Opportunity and challenges to application. J. Anim. Sci. 81:E9 17. Herd, R.M. and S.C. Bishop. 2000. Genetic variation in residual feed intake and its association with other production traits in British Hereford cattle. Live. Prod. Sci. 63:111 119. Ittner, N.R., C.F. Kelly and H.R. Guilbert. 1951. Water consumption of Hereford and Brahman cattle and the effect of cooled drinking water in a hot clim ate. J. Anim. Sci. 10:742 751. Jensen, S., C. Parsons, and J. England. 2006. Cattle producer s library : Castration of bulls. http://www.csubeef.com/dmdocuments/749%20COLOR.pdf Accessed June 12, 2009. Killinger, K. M., C. R. Calkins, W. J. Umberger, D. M. Feuz, and K. M. Eskridge. 2004. Consumer sensory acceptance and value for beef steaks of similar tenderness but differing in marbling levels J. Anim. Sci. 82:3294 3301. King, J. 1965. Ceruloplasmin. Pages 108 110 in Practical Clinical Enzymology Van Nostrand, London, UK.

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81 Knight, T.W., G.P. Cosgrove, A.F. Death, and C.B. Anderson. 2000. Effect of ag e of pre and post pubertal castration of bulls on growth rates and carcass quality. New Zealand J. Agric. Res. 43:585 588. Knight, T.W., G.P. Cosgrove, A.F. Death, and C.B. Anderson. 1999. Effect of interval from castration of bulls to slaughter on carcass characteristics and meat quality. New Z ealand J. Agric. Res. 42:269 277. Koch, R.M., L.A. Swiger, D. Chambers and K.E. Gregory. 1963. Efficiency of feed use in beef cattle. J. Anim. Sci. 22:486 494. Lancaster, P.A., G.E. Carstens, F.R.B. Ribeiro, L.O. Tedeschi, and D.H. Crews, Jr. 2009. Chara cterization of fed efficiency traits and relationships with feeding behavior and ultrasound carcass traits in growing bulls. J. Anim. Sci. 87:1528 1539. Lents, C.A., F.J. White, L.N. Floyd, D.L. Gay, and R.P. Wettemann. 2006. Effects of method and timing of castration and the use of an estrogenic growth stimulant on weight gain of bull calves. Prof. Anim. Sci. 22:126 131. Lents, C.A., F.J. White, L.N. Floyd, R.P. Wettemann, and D.L. Gay. 2001. Method and timing of castration influences performance of bull calves. Oklahoma Experiment Station Report. Lofgreen, G.P., R.L. Givens, S.R. Morrison and T.E. Bond. 1975. Effect of drinking water temperature on beef cattle performance. J. Anim. Sci. 40:223 229. Mader, T. L., M. S. Davis, and T. Brown Brandl. 2006. Enviromental factors influencing heat stress in feedlot cattle. J. Anim. Sci. 84:712 719. Makimura, S. and N. Suzuki. 1982. Quantitative determination of bovine serum haptoglobin and its elevation in some inflammatory diseases. Nippon Juigaku Zasshi 44:15 21. Meyer, A.M., M.S. Kerley and R.L. Kallenbach. 2008. The effect of residual feed intake classification on forage intake by grazing beef cows. J. Anim. Sci. 86:2670 2679. Meyer, U., W. Stahl, and G. Flachowsky. 2006. Investigations on the water intake of growing bulls. Livest. Prod. Sci. 103:186 191. National Animal Health Monitoring Service (NAHMS). 1997. Health management. http://nahms.aphis.usda.gov/beefcowcalf/ Accessed October 15, 2009. Nkrumah, J. D., E. K. Okine, G. W. Mathison, K. Schmid, C. Li, J. A. Basarab, M.A. Price, Z. Wang and S. S. Moore. 2006. Relationships of feedlot feed efficiency, performance, and feeding behavior with m etabolic rate, methane production, and energy partitioning in beef cattle. J. Anim. Sci. 84:145 153.

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82 Nkrumah, J.D., D.H. Crews, Jr., J.A. Basarab, M.A. Price, E.K. Okine, Z. Wang, C. Li, and S.S. Moore. 2007a. Genetic and phenotypic relationships of feedi ng behavior and temperament with performance, feed efficiency, ultrasound, and carcass merit of beef cattle. J. Anim. Sci. 85:2382 2390. Nkrumah, J.D., J.A. Basarab, Z. Wang, C. Li, M.A. Price, E.K. Okine, D.H. Crews, Jr., and S.S. Moore. 2007b. Genetic a nd phenotypic relationships of feed intake and measures of efficiency with growth and carcass merit of beef cattle. J. Anim. Sci. 85:2711 2720. Platter, W. J., J. D. Tatum, K. E. Belk, S. R. Koontz, P. L. Chapman, and G. C. Smith. 2005. Effects of marblin steaks. J. Anim. Sci. 83:890 899. Price, E. O., T. E. Adams, C. C. Huxsoll, and R. E. Borgwardt. 2003. Aggressive behavior is reduced in bulls actively immunized against gonadotropin r eleasing hormone. J. Anim. Sci. 81:411 415. Qiu, X., J. D. Arthington, D. G. Riley, C. C. Chase, Jr., W. A. Phillips, S. W. Coleman, and T. A. Olson. 2007. Genetic effects on acute phase protein response to the stresses of weaning and transportation in be ef calves. J. Anim. Sci. 85:2367 2374 Ratcliff, M. D., E. B. Kegley, S. L. Krumpelman and J. A. Hornsby. 2005. Effect of method and timing of cas tration on n ewly arrived stocker cattle. Arkansas Animal Science Research Report. Fayetteville, AR. P 115 117 Seideman, S.C., H.R. Cross, R.R. Oltjen, and B.D. Schanba cher. 1982. Utilization of the i ntact male for red meat production: A review. J. Anim. Sci. 55:826 840. Stafford, K.J., D.J. Mellor, S.E. Todd, R.A. Bruce, and R.N. Ward. 2002. Effects of local a naesthesia or local anaesthesia plus a non steroidal anti inflammatory drug on the acute cortisol response of calves to five different methods of castration. Research in Veterinary Science 73:61 70. Thiago, L. R. L., M. Gill, and M. S. Dhanoa. 1992. Studi es of method of conserving grass herbage and frequency of feeding in catt le. Br. J. of Nutr 67:305 318. Ting, S.T.L., B. Earley, J.M.L. Hughes, and M.A. Crowe. 2003. Effect of ketoprofen, lidocaine local anesthesia, and combined xylazine and lidocaine ca udal epidural anesthesia during castration of beef cattle on stress responses, immunity, growth, and behavior. J. Anim. Sci. 81:1281 1293 Troxel, T.R. and B.L. Barham. 2007. Comparing the 2000 and 2005 factors affecting the selling price of feeder cattle sold at Arkansas livestock auctions. J. Anim. Sci. 85:3425 3433.

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83 Wales, W. J., E. S. Kolver, P. L. Thorne, and A. R. Egan. 2004. Diurnal variation in ruminal pH on the digestibility of highly digestible perennial ryegrass during continuous culture fermen tations. J. Dairy Sci. 87:1864 1871. Warwick, E.J., P.A. Putnam, R.L. Hiner, and R.E. Davis. 1970. Effects of castration on performance and carcass characters of monozygotic bovine twins. J. Anim. Sci. 31:296 301. Winchester, C.F. and M.J. Morris. 1956. Water intake rates of cattle. J. Anim. Sci. 15:722 740. Worrell, M.A., D. C. Clanton, and C. R. Calkins. 1987. Effect of weight at castration on steer performance in the feedlot. J. Anim. Sci. 64:343:347 Zweiacher E.R., R. M. Durham, B. D. Boren, and C. T. Gaskins. 1979. Effects of method and time of castration of feeder calves. J. Anim. Sci. 49:5 9

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84 BIOGRAPHICAL SKETCH Thomas Micajah Warnock III (Trey) was born in Plan t City, Florida, in 1985 to Tommy and Pam W arnock. Trey was raised in Plant City and was actively involved in church, athletics, and The National FFA Organization. Trey graduated from Plant City High School in 2003 and then attended Hillsborough Community College to earn his Associate of Arts degre e. In 2005, Trey began his academic tenure at the University of Florida where he quickly found his home in the Animal Sciences Department and Alpha Gamma Rho house. While in the Animal Sciences Department Trey worked for the IFAS Beef Teaching Unit under Mr. Jesse Savell Trey also was fortunate enough to complete two beef industry internships while in his undergraduate program, one in Okeechobee, Florida for the Lykes Bros. Ranch, and the other in Benjamin, Texas for the Williamson Cattle Ranch. Trey com pleted his Bachelor of Science degree in 2008 and quickly began his graduate program the following semester. Trey worked on a master s degree under the supervision of Dr. Todd A. Thrift in Animal Sciences and continued to work at the Beef Teaching Unit, as well as being a teaching assistant for several animal science courses including cow/calf management, beef stocker and feedlot management, meats, livestock and carcass evaluation, and large animal practicum.