<%BANNER%>

Performance of Lactating Holstein Cows Fed Catfish Oil


PAGE 1

PERFORMANCE OF LACTATING HOLSTEIN COWS FED CATFISH OIL By ALEXANDRA KARINA AMOROCHO GARCIA A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2003

PAGE 2

This thesis is dedicated to God and th e most important people during my masters program: my father, mother, sister, and Dr. Ch arles Staples. I would like to thank the Lord God for giving me the opportunities and sk ills to attain this goal; and for support throughout the trials in its attainment. I would like to thank my father, Nelson Am orocho, for his love and guidance during his life and after. I would like to thank my mother, Benilda Amorocho; and sister, Najesda Amorocho, for helping and encouraging me, for inspiring me to do my best each and every day, and for their love and support. Finally, I thank my mentor Dr. Charles Stap les for his endless patience and unconditional help; and for giving me this great opportunity.

PAGE 3

ACKNOWLEDGMENTS I would like to acknowledge the supervisor of my committee, Dr. Charles R. Staples, for accepting me into his research program, for his guidance, and for helping to make this work a real success. I also would like to thank the members of my committee: I thank Dr. Mary Beth Hall for giving me the opportunity to work hard and to reach my goals; and I thank Dr. Lokenga Badinga for his assistance during this time. The University of Florida, Department of Animal Sciences; Protein Products, Inc. (Gainesville, GA); and U. S. Sugar Corp. (Clewiston, FL) supplied the resources needed for this research, which I appreciate greatly. I am indebted to the staff of the Dairy Research Unit (Hague, FL), with special thanks to Carrie Bradley for feeding the animals during the study, and to all the employees of the farm who made this study possible. I also would like to thank these students and friends: Najesda Amorocho, Ricardo Boger, Sergio Burgos, Heidi Bissell, Colleen Larson, Lucia Holtshausen, and Jose Rossignoli, who contributed to this research with their time and excellent effort. Gratitude is extended to Jocelyn Jennings for her guidance and instruction in the dairy nutrition laboratory. This research would not have been possible without the contributions of all. iii

PAGE 4

TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iii LIST OF TABLES.............................................................................................................vi LIST OF FIGURES.........................................................................................................viii ABBREVIATIONS.............................................................................................................x ABSTRACT.......................................................................................................................xi CHAPTER 1 INTRODUCTION........................................................................................................1 Fatty Acid Metabolism.................................................................................................1 Sources and Composition of Fat in the Dairy Cow Diet..............................................4 2 REVIEW OF THE LITERATURE ON FATS IN RUMINANT DIETS.....................7 Effects of Yellow Grease in Ruminant Diets...............................................................7 Effects of YG and Tallow in Ruminant Diets............................................................11 Effects of Tallow in Ruminant Diets..........................................................................14 Effects of Tallow and Fish Oil in Ruminant Diets.....................................................37 Effects of Fish Oil in Ruminant Diets........................................................................38 3 PERFORMANCE OF LACTATING HOLSTEIN COWS FED CATFISH OIL......46 Introduction.................................................................................................................46 Materials and Methods...............................................................................................47 Cows and Diets....................................................................................................47 Collection of Samples and Analysis....................................................................48 Apparent Digestibility.........................................................................................51 Rate and Extent of Digestion...............................................................................51 Sampling and Analysis of Ruminal Fluid...........................................................52 Statistical Analysis..............................................................................................53 Results and Discussion...............................................................................................55 Diet Composition.................................................................................................55 Intake Response and Apparent Digestibility.......................................................55 In situ Dry Matter and Neutral Detergent Fiber Digestion..................................58 iv

PAGE 5

Milk Production and Composition......................................................................59 Fatty Acid Composition of Milk Fat...................................................................60 Ruminal Fermentation.........................................................................................61 Blood Metabolites...............................................................................................63 Summary.....................................................................................................................64 APPENDIX........................................................................................................................75 LITERATURE CITED......................................................................................................88 BIOGRAPHICAL SKETCH.............................................................................................94 v

PAGE 6

LIST OF TABLES Table page 1-1. Average fatty acid profile of tallow, yellow grease, and marine fish oil....................5 3-1. Fatty acid profile of catfish oil..................................................................................48 3-2. Ingredient and chemical composition of experimental diets containing catfish oil (CFO) fed to lactating Holstein cows in summer.....................................................65 3-3. Dry matter intake (DMI), apparent digestibility coeficients of DM, CP, NDF, ADF and ether extract (EE), body weight change, and rectal temperatures (RT) of lactating Holstein cows fed catfish oil (CFO) in summer........................................66 3-4. In situ lag, rate, and extent of DM and NDF digestion of corn silage by lactating Holstein cows fed catfish oil (CFO) in summer.......................................................67 3-6. Fatty acid composition of milk fat of lactating Holstein cows fed catfish oil (CFO) in summer.................................................................................................................68 3-7.Volatile fatty acid concentration, pH, microbial protein production, and protozoa numbers in ruminal fluid and pH of urine and feces of lactating Holstein cows fed catfish oil (CFO) in summer.....................................................................................69 3-8. Concentrations of plasma urea, glucose and insulin of lactating Holstein cows fed catfish oil (CFO) in summer.....................................................................................69 A-1. Average temperature (Temp), relative humidity (RH), and temperature humidity index (THI) in 6-h increments on collection days measured within the free stall barn at the Dairy Research Unit at Hague, Florida. 1 ................................................75 A-2. Average temperature (Temp),relative humidity (RH), and temperature humidity index (THI) on 6-h increments on collection days measured outside the free stall barn at the Dairy Research Unit at Hague, Florida. 1 ................................................79 A-3. Average temperature (Temp), relative humidity (RH), and temperature humidity index (THI) by period on collection days measured within the free stall barn at the Dairy Research Unit at Hague, Florida....................................................................83 vi

PAGE 7

A-4. Average temperature (Temp), relative humidity (RH), and temperature humidity index (THI) by period on collection days measured outside the free stall barn at the Dairy Research Unit at Hague, Florida....................................................................83 vii

PAGE 8

LIST OF FIGURES Figure page 3-1. Ruminal fluid pH for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO).............................................................................................70 3-2. Molar proportion of acetate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO).....................................................70 3-3. Molar proportion of butyrate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO).....................................................71 3-4. Molar proportion of isobutyrate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO)............................................71 3-5. Molar proportion of 2-methylbutyrate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO)....................................72 3-6. Molar proportion of isovalerate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO)............................................72 3-7. Protozoa numbers in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, 3.0% catfish oil (CFO)............................................................................73 3-8. Urine pH for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO).......................................................................................................73 3-9. Fecal pH for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO).......................................................................................................74 A-1. Minimum (MIN) and maximum (MAX) temperature humidity index (THI) recorded inside the free stall barn during each day of collection averaged across the three experimental periods.......................................................................................83 A-2. Minimum (MIN) and maximum (MAX) temperature humidity index (THI) recorded inside the free stall barn during each day of collection of experimental period 1.....................................................................................................................84 A-3. Minimum (MIN) and maximum (MAX) temperature humidity index (THI) recorded inside the free stall barn during each day of collection of experimental period 2.....................................................................................................................84 viii

PAGE 9

A-4. Minimum (MIN) and maximum (MAX) temperature humidity index (THI) recorded inside the free stall barn during each day of collection of experimental period 3.....................................................................................................................85 A-5. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded outside the free stall barn during each day of collection averaged across the three experimental periods................................................................................................85 A-6. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded outside the free stall barn during each day of collection of experimental period 1..86 A-7. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded outside the free stall barn during each day of collection of experimental period 2.86 A-8. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded outside the free stall barn during each day of collection of experimental period 3..87 A-9. Hourly measurements of ruminal fluid pH of cows fed diets containing 0, 1.5, or 3.0% catfish oil (CFO) after feeding........................................................................87 ix

PAGE 10

x ABBREVIATIONS ACC acetyl Co A carboxylase SCD steroyl CoA desaturase ADF acid detergent fiber SCS somatic cell score AH alfalfa hay TG triglycerides BH bermudagrass hay TMR total mixed ration BUN blood urea nitrogen UFO unprotected fish oil CFO catfi sh oil VFA volatile fatty acid CLA conjugated linoleic acid WCS whole cottonseed CP crude protein YG yellow grease CS corn silage WSB whole soybeans CWG choice white grease DHA docosahexaenoic acid DM dry matter DMI cry matter intake EE ether extr act EL early lactation EPA eicosapentaenoic acid ESC ethanol soluble carbohydrate ESB extruded soybeans FA fatty acids FAS fatty acid synthase FCM fat corrected milk FO fish oil HAS high alfalfa silage HCS high corn silagle HOC high oil corn HR DP high ruminally degradable protein HYG hydrogenated yellow grease LCFA long chain fatty acid LL late lactation LPL lipoprotein lipase LRDP low ruminally degradable protein NDF neutral detergen fiber OM organic matter PF prilled fatty acids PFO p rotected fish oil PHT partially hydrogenated tallow SCC somatic cell count

PAGE 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 PERFORMANCE OF LACTATING HOLSTEIN COWS FED CATFISH OIL By Alexandra Karina Amorocho Garcia May 2003 Chair: Charles R. Staples Major Department: Animal Sciences The objective of this study was to evaluate catfish oil as a dietary ingredient for lactating Holstein cows. Twelve multiparous Holstein cows (six fitted with a cannula in the rumen and six intact) were assigned to the experiment at an average of 195 27 days in milk. Catfish oil was suspended in liquid molasses (27% of DM), mixed with grain, and fed as a totally mixed ration at 0, 1.5, and 3% of dietary DM. The fatty acid profile of catfish oil was primarily 18.7% palmitic, 4.9% palmitoleic, 5.0% stearic, 47% oleic, 14% linoleic, 1.1% eicosapentaenoic, and 3.1% docosahexaenoic acids. Dietary treatments were arranged in a 3 x 3 Latin square design replicated four times. Each period lasted 27 days (14 days for adaptation to a new diet and 13 days for data collection). Milk production and dry matter intake were measured daily. Blood was collected on Days 26 and 27. Urine and fecal samples were collected and measured for pH on Days 22 and 23. Rumen fluid was collected hourly for 8 hours on Day 15. Apparent digestibility of nutrients was calculated by the marker ratio technique. In situ DM and NDF digestibility of corn silage were measured on Days 25, 26, and 27. Intake xi

PAGE 12

of dry matter increased linearly (P = 0.01) as intake of catfish oil increased (23.0, 24.4, and 25.4 kg/d). Production of milk was unchanged by the feeding of catfish oil (29.0, 29.0, and 29.4 kg/d). Concentrations of milk fat (3.57, 3.60, and 3.48%) and protein (3.21, 3.18, and 3.23%) were unchanged by feeding catfish oil. Concentrations of plasma glucose (57.8, 55.1, and 56.0 mg/100 mL) and urea nitrogen (11.6, 11.0, and 12.0 mg/100 mL) were not affected by dietary treatments. The pH of urine (8.05, 8.05, and 8.06) and feces (6.69, 6.71, and 6.68) were unchanged by feeding increasing amounts of catfish oil. Average ruminal fluid pH decreased linearly (P = 0.0001) (6.40, 6.20, and 6.15), as did the molar proportions of acetate (P = 0.02) (64.5, 64.2, and 63.4%). The molar proportions of propionate increased linearly (P = 0.02) (19.4, 20.0, and 20.4%) as did those of butyrate (P = 0.08) (12.0, 12.4, and 12.5%) as intake of catfish oil increased. Ruminal protozoa numbers were unchanged by treatments. Apparent digestibility coefficients of DM, CP, NDF, and ADF were improved as intake of catfish oil increased. In situ lag, rate and extent of corn silage DM digestion were similar across dietary treatments. However, in situ digestion rate of NDF was increased linearly (P = 0.04) as intake of catfish oil increased (0.023, 0.024, and 0.029 h -1 ). Mixing catfish oil with liquid molasses at up to 3% of dietary dry matter stimulated dry matter intake and digestibility of lactating Holstein cows but did not alter lactation performance. xii

PAGE 13

CHAPTER 1 INTRODUCTION In general, energy intake is a primary limitation on milk yield for high producing dairy cows and is determined by the net energy concentration of the diet and dry matter intake (Allen, 2000). During periods of heat stress, a decrease in energy intake followed by a decrease in milk production is a routine response. To minimize the loss of milk production and still meet the nutrient requirement of the animal, the energy density of the diet may be increased. Dietary fatty acids can be an ideal feed ingredient during heat stress periods because fats have a greater energy density than other feeds, are used with a high efficiency, and produce less heat during digestion compared to other major feedstuffs (NRC, 2001). Fatty Acid Metabolism Lipid metabolism in the rumen is characterized by rapid lipolysis, fatty acid hydrogenation and de novo lipid cellular synthesis by microorganisms (Bauchart et al., 1990). Microbial cleavage of the glycerol molecule from the individual fatty acids (lipolysis) occurs with dietary glycolipids, phospholipids, and triglycerides (Chilliard et al., 2000). Lipolytic bacteria rapidly carry out this process of hydrolysis in the rumen. Protozoa may not be capable of lipolytic activity (Palmquist and Jenkins, 1980). Minimal loss of fatty acids from the rumen occurs either by absorption across the ruminal epithelium or by catabolism to volatile fatty acids (VFA) or CO 2 (Jenkins, 1993). Unsaturated free fatty acids have relatively short half-lives in ruminal contents because they are rapidly hydrogenated by microbes to more saturated fatty acids (Jenkins, 1993). 1

PAGE 14

2 Polyunsaturated fatty acids are first isomerized and then hydrogenated. For example, linoleic acid (cis-9, cis-12 C18:2) is isomerized to conjugated linoleic acid (CLA) (cis-9, trans-11 C18:2); and then hydrogenated first to transvaccenic acid (trans 11 C18:1) and then to stearic acid (C18:0). Biohydrogenation of unsaturated fatty acids depends on the nature and amount of dietary lipids; the efficacy and type of technological treatment of feedstuffs; and the nature and amount of forage, concentrates, and minerals in the diets that influence either the microbial ecosystem, the transit rate of digesta, or the interaction of fatty acids with digestion (Chilliard et al., 2000). The rate of lipolysis and biohydrogenation is sensitive to pH, being reduced at lower ruminal pH. First, lipolysis is limited and thus biohydrogenation which can only occur on free fatty acids (Chilliard et al., 2000). In addition, dietary fatty acids can be incorporated into cellular lipids of ruminal bacteria and protozoa and thus pass out of the rumen in an unsaturated form. Also microbes can synthesize fatty acids de novo from carbohydrate precursors (Jenkins, 1993). Total lipid content of bacterial dry mass in the rumen ranges from 10 to 15% (Jenkins, 1993), and proportions are lower in liquid-associated bacteria than in solid-associated bacteria (Bauchart et al., 1990). Lipids reaching the duodenum consisted of fatty acids from both dietary and microbial origins. Fatty acids of less than 14 carbons are absorbed by brush border cells of the small intestine and enter the blood directly (Palmquist and Jenkins, 1980). Long chain fatty acids ( C16) are incorporated into micellar solution by bile salts and lysolecithin. Micelles are disrupted on the surface of the microvilli on the intestinal mucosa and free fatty acids are taken up by the mucosal cell. Absorbed free fatty acids are reesterified in the mucosal cell into triglycerides. Triglycerides are packaged along

PAGE 15

3 with phospholipids, cholesterol esters and apolipoproteins into chylomicrons or very low density lipoproteins that are then transported to the lymphatic circulation and blood vessels (Bauchart, 1993). Milk fat triglycerides are synthesized either from fatty acids that are taken up from the blood or by de novo synthesis by the mammary gland. The mammary gland uses plasma nonesterified fatty acids released from adipose tissue or long chain fatty acids available from the diet as a source of long chain fatty acids because of the inability of the mammary gland to convert C16:0 to C18:0 by chain elongation. Most of the fatty acids arising from de novo synthesis are saturated, short to medium chain fatty acids (C4:0 to C16:0). Long chain fatty acids (LCFA) are potent inhibitors of short chain fatty acid synthesis by the mammary gland through a direct inhibitory effect on acetyl CoA carboxylase activity, which often results in a decrease in the percentage of medium chain fatty acids (C8:0 to C14:0) in milk fat (Chilliard et al., 2000) during lipid supplementation. Addition of fat to dairy cow diets has been associated with changes in ruminal fermentation, mainly depressions in fiber digestion. Devendra and Lewis (1974) postulated that reduced digestibility could be caused by prevention of microbial attachment by physical coating of the fiber with fat. Supplemental fats may have an inhibitory effect on microbial activity (Palmquist and Jenkins, 1980) especially on cellulotic strains of bacteria where long chain fatty acids (LCFA) may interfere with nutrient uptake by the bacteria (Maczulack et al., 1981). However this is not always the case because gram positive-methanogenic bacteria were inhibited by LCFA addition thus depressing methane production, whereas cellulolytic bacteria were not affected (Devendra and Lewis, 1974). Addition of cellulose to LCFA-containing culture media,

PAGE 16

4 alleviated the cell surface interaction of bacteria with LCFA (Maczulack et al., 1981). Also the presence of cations like calcium and magnesium may form mineral soaps with fat (Devendra and Lewis 1974) allowing normal nutrient uptake by the microbes. Despite the potential negative effect of fat supplementation on ruminal fermentation, fat continues to be a mainstay in diets for dairy cows. Sources and Composition of Fat in the Dairy Cow Diet Some reasons to include fats in the diets of ruminants are that they provide a source of concentrated energy, act as carriers of fat-soluble vitamins, may increase palatability, may reduce dustiness in the feed, may reduce feed wastage, may increase feed efficiency, and may decrease frictional wear of mixing machinery (Devendra and Lewis, 1974). Diets made up of forages and grains for ruminants generally contain between 2 and 5% ether-extractable compounds (of which about one-half are fatty acids and the other half are nonnutritive waxes, cutins, chlorophyll, etc.) (Chilliard, 1993). In lactating cows, fatty acid output in the milk usually exceeds daily intake of fatty acids (Palmquist and Jenkins, 1980). Dietary fatty acids can be incorporated directly into milk fat. The remaining fatty acids in milk (mainly 14 carbons and shorter) are synthesized de novo from acetic and butyric acids produced by ruminal microorganisms. Fats in diets for the lactating dairy cow can be from vegetable (forages, oils, and seeds) and animal (tallow, lard, and fish oils) sources. Supplemental fats can have different fatty acid profiles that differ according to chain length and number of double bonds. Linoleic acid (C18:2) predominates in most seeds, whereas linolenic acid (C18:3) is usually the most common fatty acid in forages. An important exception to this generalization is the very high concentration of C18:3 (57%) in linseed oil (Palmquist and Jenkins, 1980). The most commonly used sources of pure fats are tallow and yellow grease. Average fatty acid

PAGE 17

5 composition of tallow and yellow grease are similar except that yellow grease contains less C18:0 and more C18:2 (Table 1-1). Marine fish oil contains many of the fatty acids found in tallow and yellow grease but also some that are unique to products derived from the ocean, namely eicosapenteanoic acid (EPA) and docosahexaenoic acid (DHA) (Table 1-1). Table 1-1. Average fatty acid profile of tallow, yellow grease, and marine fish oil. Fatty acid Tallow 1 Yellow grease 2 Marine fish oil 3 Myristic (C14:0), % 2.9 2.0 7.2 Palmitic (C16:0), % 25.3 21.1 15.5 Palmitoleic (C16:1), % 3.3 4.2 7.5 Stearic (C18:0), % 18.0 11.3 3.0 Oleic (C18:1), % 43.3 43.5 11.9 Linoleic (18:2), % 3.8 13.9 1.1 Linolenic (C18:3), % 0 0 1.7 Eicosapentaenoic (20:5), % 0 0 13.8 Docosapentaenoic (22:5), % 0 0 2.0 Docasahexaenoic (22:6), % 0 0 9.1 1 Average of values reported by Adams et al. (1995), Avila et al. (2000), Elliot et al. (1993), Getachew et al. (2001), Grummer et al. (1993), Jenkins et al. (1998), Lewis et al. (1999), Oldick et al. (1997), Onetti et al. (2001), Onetti et al. (2002), Pantoja et al. (1996), Ruppert et al. (2003), Shauff et al. (1992), and Wu et al. (1993). 2 Average of values reported by Avila et al. (2000), DePeters et al. (1987), Jenkins and Jenny (1989), Martinez et al. (1991), and Oldick et al. (1997). 3 Average of values reported by AbuGhazaleh et al. (2002), Chilliard and Doreau (1997), Donovan et al. (2000), Doreau and Chilliard (1997), Keady et al. (2000), and Whitlock et al. (2002). In the search for fat supplements to use in dairy cows diets, preliminary work in Florida indicated that mixing catfish oil with liquid molasses dramatically improved intake of the liquid supplement by beef cows on rangeland (F. M. Pate, personal communication). Catfish oil has not been evaluated as a feedstuff for dairy cows. Because catfish are fresh water fish, their fatty acid profile differs from that of marine fish in that omega-3 fatty acids, EPA and DHA, are in lower concentrations. This is because pond-raised fresh water fish consume less algae, the source of omega-3 fatty

PAGE 18

6 acids. Feeding marine fish oil to cows has improved milk production but can decrease dry matter intake (Chilliard and Doreau, 1997; Keady et al., 2000). If catfish oil can improve feed intake as it did with beef cows, then it may prove to be a very effective energy supplement for increasing milk production. Because catfish oil has a fatty acid profile similar to that of tallow and yellow grease, the effects of feeding tallow and yellow grease on lactating dairy cow performance are included in the literature review in the next section.

PAGE 19

CHAPTER 2 REVIEW OF THE LITERATURE ON FATS IN RUMINANT DIETS Effects of Yellow Grease in Ruminant Diets Jenkins and Jenny (1989) fed eight lactating Holstein cows yellow grease (YG) or hydrogenated YG (HYG). The fatty acid composition of YG was 2.5% C14:0, 25.5% C16:0, 14.7% C18:0, 43.4% C18:1, and 8.0% C18:2. The fatty acid composition of HYG was 1.7% C14:0, 21.6% C16:0, and 75.6% C18:0. The concentrates contained the fat sources with fats replacing a portion of the corn. Corn silage was the source of forage (55% of dietary DM). Dietary treatments were control diet (no added fat), 5% YG, 3% HYG, and 5% HYG. Feeding YG decreased DM intake compared to the control and HYG diets (22.9, 20.5, 22.5, and 23.5 kg of DM for control, 5% YG, 3% HYG, and 5% HYG, respectively). Milk yield of fat-supplemented cows were unchanged but tended (P = 0.07) to be greater for cows fed the 5% HYG diet (32.0, 31.5, 31.9, and 33.6 for control, 5% YG, 3% HYG, and 5% HYG, respectively). Milk fat percentage was decreased by YG but increased when 5% HYG was fed (3.50, 2.83, 3.34 and 3.74% for control, 5% YG, 3% HYG, and 5% HYG, respectively). Milk protein percentage was decreased by the fat supplements but was not different among the cows fed the fat-supplemented diets (3.20, 3.07, 3.17, and 3.09% for control, 5% YG, 3% HYG, and 5% HYG, respectively). Plasma glucose tended (P = 0.10) to be greater for cows fed the fat supplements. Apparent DM digestibility was greater by cows fed YG (70.0, 72.0, 69.6, and 68.7% for control, 5% YG, 3% HYG, and 5% HYG, respectively), whereas apparent digestibility of acid detergent fiber (ADF) was depressed similarly in cows fed 7

PAGE 20

8 supplemental fat (31.6, 21.6, 18.9, and 20.0 for control, 5% YG, 3% HYG, and 5% HYG, respectively). Ruminal fluid of cows fed YG contained a greater molar proportion of propionate (26.2 vs. 21.9 mol/100mol), isovalerate (2.0 vs. 1.6 mol/100 mol), and valerate (2.0 vs. 1.6 mol/100 mol), but less acetate (57.7 vs. 61.8 mol/100 mol), butyrate (10.5 vs. 12.2 mol/100 mol), and acetate to propionate ratio (2.2 vs. 2.9 mol/100 mol) than ruminal fluid of cows fed HYG. Martinez et al. (1991) fed eight lactating Holstein cows YG, whole cottonseed (WCS), and niacin. The fatty acid composition of YG was 3.4% C14:0, 24.3% C16:0, 14.1% C18:0, 42.1% C18:1, and 10.0% C18:2. The fatty acid composition of whole cottonseed was 2.3% C14:0, 23.5% C16:0, 2.5% C18:0, 17.3% C18:1, and 53.2% C18:2. Dietary treatments were the following (DM basis): 1) 2% fat, no niacin, 2) 4% fat, no niacin, 3) 2% fat with 0.055% niacin, and 4) 4% fat with 0.055% niacin. The 2% fat diets contained fatty acids from whole cottonseed, whereas the 4% fat diets contained 2% of the fatty acids from whole cottonseed and 2% of the fatty acids from YG. The forage source was chopped alfalfa hay (40% of dietary DM). Dry matter intake and milk protein percentage were not affected by either niacin or fat supplementation. Percentage of milk fat tended (P = 0.10) to increase in cows fed diets containing 2% YG (3.29 vs. 3.42%) as did milk yield (30.8 vs. 31.5 kg/d). As a result, milk fat yield was increased by feeding YG (1.01 vs. 1.07 kg/d). No differences for dependent variables were detected due to niacin. Proportions of short and medium-chain fatty acids (C6:0 to C16:0) of milk fat were decreased and the proportion of long-chain fatty acids (C18:0, C18:1, and C18:3) were increased, except C18:2 which was decreased by supplementing YG.

PAGE 21

9 DePeters et al. (1987) fed twelve lactating Holstein cows YG. Cows were subdivided into two status categories based on stage of lactation. Groups consisted of cows in early (EL) and late (LL) lactation. The fatty acid composition of YG was 2.4% C14:0, 17.9% C16:0, 12.1% C18:0, 46.8% C18:1, and 12.8% C18:2. Dietary treatments were 0, 3.5, or 7% added YG (DM basis). The forage source was chopped alfalfa hay (50% of dietary DM). Yellow grease replaced a portion of the cracked corn in the concentrate. Dry matter intake was greater for cows fed diets containing YG (140.8, 155.3, and 148.0 kg/wk for 0, 3.5, and 7% YG, respectively). Milk yield was greater for cows fed diets containing YG (200.3, 237.4, and 223.5 kg/wk for 0, 3.5, and 7% YG, respectively). Percentage of milk fat was depressed from cows fed the 7% YG diet compared with those fed the 0 and 3.5% YG diets (3.45, 3.47, and 3.04% for 0, 3.5, and 7% YG, respectively). Percentage of milk protein was depressed by including YG at 3.5 or 7% (3.33, 3.21, and 3.21% for 0, 3.5, and 7% YG, respectively). The fatty acid composition of milk was affected when cows were YG. Proportions of short-chain and medium-chain fatty acids (C6:0 to C16:0) were depressed whereas long-chain fatty acids (C18:0 and C18:1) were elevated by feeding YG. Apparent digestibilities of DM, NDF, and ADF were not affected by YG, however, apparent digestibility of ether extract was increased. Cant et al. (1991) fed four lactating primiparous cows, fitted with a rumen cannula, diets of 50% forage and 50% concentrate (DM basis). The forage source was chopped alfalfa hay. Dietary treatments were 0 or 4% YG (DM basis). Yellow grease replaced a proportion of the corn and barley. Dry matter intake was not affected but apparent DM digestibility was reduced by YG (71.3 vs. 68.1% for 0 and 4% YG, respectively). Milk

PAGE 22

10 production was improved 14% with YG (23.8 vs. 27.1 kg/d). Milk fat percentage (3.5 vs. 3.7%) and milk fat yield (0.8 vs. 1.0 kg/d) were improved with the addition of YG. Milk protein percentage was lower when YG was added (3.15 vs. 3.0%) but milk protein yield was unchanged. Dry matter and NDF digestibilities were reduced by dietary YG. Cant et al. (1993) fed YG to four lactating primiparous cows fitted with rumen cannulas. Diets were 50% chopped alfalfa hay and 50% concentrate (DM basis) with YG at 0 or 4% of dietary DM. Milk yield and fat percentage were not affected by YG. A small but statistically significant drop in plasma glucose concentration was detected with added dietary YG (0.81 vs. 0.73 mM for 0 and 4% YG diets, respectively). Milk protein percentage was depressed by YG addition (3.3 vs. 3.1%). Milk fatty acid proportions of C6:0 to C16:0 were decreased whereas those of C18:0 and C18:1 were increased by YG addition. Nianogo et al. (1991) utilized twelve multiparous Holstein cows calving in fall and twelve multiparous Holstein cows calving in summer from calving to 17 wk postpartum. The forage source was wheat silage offered in ad libitum amounts separate from concentrate. Two sources of protein used were soybean meal serving as a high ruminally degradability protein (HRDP) source and a mixture of heated soybean meal and corn gluten meal serving as a low ruminally degradability protein (LRDP) source. The forage to concentrate ratios were 23.5:76.5 in fall and 28.1:71.9 in summer (DM basis). Dietary treatments were the following (% of dietary DM): 1) 0% YG with HRDP, 2) 0% YG with LRDP, 3) 5.3% YG with HRDP, and 4) 5.3% YG with LRDP. Addition of YG to the diet had no influence on DMI, milk production, 4% FCM production, or percentages and yields of milk fat and milk protein. Cows receiving YG lost more BW than control cows

PAGE 23

11 (2.6 vs. 24.4 kg/16 wk). Digestibility of DM (68.0 vs. 70.1%) and CP ( 57.4 vs. 64.5%) were greater whereas digestibility of NDF (59.3 vs. 55.2%) was lower in cows receiving YG. Part of the depression in apparent CP digestion caused by feeding LRDP was alleviated by adding YG to diets containing LRDP (YG by RDP interaction; 61.3, 53.4, 66.6, and 62.3% for 0% YG-HRDP, 0% YG-LRDP, 5.3% YG-HRDP, and 5.3% YG-LRDP, respectively). Effects of YG and Tallow in Ruminant Diets Avila et al. (2000) fed four ruminally and duodenally cannulated midlactation Holstein cows tallow, YG or a blend of tallow and YG. The fatty acid composition of tallow was 3.7% C14:0, 27.3% C16:0, 19.3% C18:0, 41.0% C18:1, and 3.5% C18:2. The fatty acid composition of YG was 1.0% C14:0, 21.3% C16:0, 6.1% C18:0, 41.5% C18:1, and 21.4% C18:2. All diets contained 12% whole cottonseed. The control diet was 4.2% ether extract (DM basis). All diets contained 45% alfalfa hay (DM basis) and the supplemental fat replaced a portion of the corn and barley. Treatments were the following: no supplemental fat (control, 3% total fatty acids, DM basis), 2% tallow, 2% YG, or 2% blend (60% tallow: 40% YG). Dry matter intakes were maintained by cows fed the supplemental fats compared to the control cows and did not differ due to fat source. Milk yield (32.7 vs. 35.2 kg/d) and milk fat yield (1.19 vs. 1.25 kg/d) increased with fat supplementation relative to control. Milk protein and fat concentrations were unchanged across treatments. The ruminal and total tract digestibilities of the fiber fractions were unaffected by the addition and source of added fat to diets. Total VFA concentrations and ruminal pH were unaffected but proportion of butyrate was decreased by fat supplementation. Feeding the fat blend decreased ruminal pH (6.27, 6.31, and 6.14) and the acetate to propionate ratio (3.14, 3.13, and 2.97) for tallow, YG, and fat

PAGE 24

12 blend, respectively compared to cows fed the single sources of fat. Plasma glucose concentration decreased linearly with increasing proportions of YG in the fat supplement (69.6, 68.5,and 67.7 mg/dl for tallow, blend, and YG, respectively). Oldick et al. (1997) utilized four ruminally cannulated multiparous Holstein cows in a 4 x 4 Latin square designed experiment. The four treatments consisted of abomasal infusions of 1) water (control), 2) 1 kg/d of glucose, 3) 0.45 kg/d of tallow, and 4) 0.45 kg/d of YG. The fatty acid composition of tallow was 2.7% C14:0, 25.4% C16:0, 22.4% C18:0, 36.2% C18:1, and 2.1% C18:2. The fatty acid composition of YG was 0.8% C14:0, 16.6% C16:0, 9.5% C18:0, 43.8% C18:1, and 17.4% C 18:2. The cows were fed a TMR containing 25.8% corn silage, 11.2% cottonseed hulls, and 63% concentrate. Dry matter intake was not affected by infusate treatments. Mean milk production was not affected by treatments, although mean 4% FCM production tended (P < 0.12) to be greater when fats were infused than when glucose was infused (26.1, 25.5, 27.7, and 27.8 kg/d for water, glucose, tallow, and YG, respectively). Mean milk fat percentage tended (P < 0.10) to increase when fat was infused relative to glucose infusion (3.0 2.9, 3.2, and 3.1% for water, glucose, tallow, and YG, respectively). Infusing YG reduced milk protein percentage compared to tallow (3.1 vs. 2.9%). Apparent digestibilities of DM, OM, and CP in the total tract were not affected by infusates. Total tract apparent digestibility of ADF was decreased when glucose, tallow, and YG were infused abomasally relative to the water infusion (54.8, 51.6, 53.2, and 51.8% for water, glucose, tallow, and YG, respectively). Apparent NDF digestibility tended (P = 0.12) to decrease in cows with the YG infusion relative to those with the infusion of tallow (59.0 vs. 57.7%). Plasma concentration of glucose (69.8 vs.

PAGE 25

13 63.2 mg/dl) and insulin (1.33 vs. 0.78 ng/ml) were greater in cows receiving the glucose infusion than in those receiving fat infusion. Getachew et al. (2001) evaluated YG, tallow and corn oil on in vitro VFA concentration and on true digestibility. A simulated TMR was prepared using beet pulp (7.1%), soybean meal (6.9%), barley grain (18%), corn grain (18%), and alfalfa hay (50%) (% of substrate DM). The fatty acid composition of tallow was 2.2% C14:0, 21.4% C16:0, 16.1% C18:0, 29.3% C18:1, and 3.5% C18:2. The fatty acid composition of YG was 1.0% C14:0, 15.9% C16:0, 9.0% C18:0, 31.3% C18:1, and 11.0% C18:2. The fatty acid composition of corn oil was 9.2% C16:0, 1.7% C18:0, 23.9% C18:1, and 48.1% C18:2. Addition of YG, tallow, or corn oil had no effect on in vitro true digestibility of the DM or on total VFA production. However all fat sources decreased acetate and isovalerate but increased propionate productions resulting in a reduction of the acetate to propionate ratio. Production of butyrate and valerate were not affected by the inclusion of YG, tallow, or corn oil. In summary, addition of YG as supplemental fat in the lactating dairy cow diet decreased (Jenkins and Jenny, 1989), had no effect (Martinez et al., 1991; Cant et al., 1991; Nianogo et al., 1991; Avila et al., 2000; Oldick et al., 1997) or increased DMI (DePeters et al., 1987; Cant et al. 1991). Yellow grease may have depressed DMI due to inhibition of ruminal fermentation or due to an effect on palatability. Milk yield of cows supplemented with YG was unchanged (Jenkins and Jenny, 1989; Cant et al., 1993; Nianogo et al., 1991; Oldick et al., 1997) or improved (Martinez et al. 1991, DePeters et al., 1987; Cant et al., 1991; Avila et al., 2000). Milk fat percentage of cows fed diets containing YG increased (Cant et al., 1991; Avila et al., 2000), decreased (Jenkins and

PAGE 26

14 Jenny, 1989); or was unchanged (Cant et al., 1993; Nianogo et al., 1991). Proportions of short-chain (C6:0 to C16:0) fatty acids in milk fat were decreased (Martinez et al., 1991;DePeters et al., 1987; Cant et al., 1993) and the proportions of long-chain fatty acids (C18:0 and C18:1) were increased (Martinez et al., 1991; DePeters et al., 1987; Cant et al., 1993). Milk protein percentage was decreased (Jenkins and Jenny, 1989; Cant et al., 1991; Cant et al., 1993), or was unaffected (Martinez et al., 1991; DePeters et al., 1987; Nianogo et al., 1991, Avila et al., 2000) by YG addition. Concentration of plasma glucose decreased with YG consumption (Cant et al., 1993; Avola et al., 2000). Ruminal fluid of cows fed YG contained similar concentrations of total VFA (Getachew et al., 2001; Avila et al., 2000), a greater molar proportion of propionate (Jenkins and Jenny, 1989; Getachew et al., 2001), a lower molar proportion of acetate (Jenkins and Jenny, 1989; Getachew et al., 2001), and a lower acetate to propionate ratio (Jenkins and Jenny, 1989; Avila et al., 2000) compared to control cows. Apparent DM digestibility was greater (Jenkins and Jenny, 1989; Nianoge et al., 1991), not affected (DePeters et al., 1987) or reduced (Cant et al., 1991) by YG feeding whereas apparent digestibility of fiber was depressed (Jenkins and Jenny, 1989; Nianogo et al., 1991) or not affected (DePeters et al., 1987). Effects of Tallow in Ruminant Diets Ruppert et al. (2003) fed multiparous Holstein cows fitted with a ruminal cannula supplemental tallow. The fatty acid composition of tallow was 2.3% C14:0, 24.2% C16:0, 17.4% C18:0, 43.4% C18:1, and 5.3% C18:2. The forage sources were corn silage and alfalfa silage. The diets were 50% forage (DM basis). Dietary treatments were high corn silage (HCS) (40:10 corn silage to alfalfa silage) or high alfalfa silage (HAS) (10:40 corn silage to alfalfa silage) and contained 0, 2 or 4% tallow (% of dietary

PAGE 27

15 DM). Intake of DM decreased linearly with increasing tallow supplementation, regardless of forage type. Cows fed the HAS diets consumed less DM (22.6, 21.4, and 21.4 kg/d) than those fed the HCS diets (24.8, 23.6, and 22.9 kg/d for 0, 2, and 4% tallow, respectively). Milk yield was not affected when tallow was supplemented to the diet. Milk fat percentage tended (P = 0.06) to decrease linearly as dietary tallow supplementation to HCS diets increased (3.18, 2.89, and 2.70% for 0, 2, and 4% tallow diets, respectively) whereas it was unchanged when supplemented to HAS diets (3.39, 3.44, and 3.41% for 0, 2, and 4% tallow diets, respectively) (forage source by tallow interaction). Yield of 3.5% FCM and yield of CP in milk was not affected by tallow supplementation. Percentage of CP in milk tended (P = 0.13) to decrease linearly as dietary tallow increased for both forage sources (3.12, 2.99, and 3.00% for 0, 2, and 4% tallow diets, respectively). The composition of milk fat was altered as tallow was supplemented to diets. Shortand medium-chain FA in milk (C6:0 to C10:0 and C14:0 to C15:0) decreased linearly as tallow supplementation increased. Concentrations of C12:0 and C16:0 decreased quadratically as tallow supplementation increased. Stearic acid concentration in milk fat increased by addition of 2% tallow but was not increased further by 4% tallow (quadratic effect of tallow). Concentration of C18:1 increased linearly as tallow supplementation increased. The content of C18:2 in milk fat decreased linearly as tallow supplementation increased. The pH and concentration of total VFA in ruminal fluid were not affected by tallow supplementation. Molar proportions of acetate and butyrate decreased linearly and the molar proportion of propionate increased linearly with increasing tallow supplementation. The apparent digestibility coefficients for DM, CP, NDF and ADF were not affected by tallow supplementation. Digestion coefficients of

PAGE 28

16 EE increased quadratically with increasing tallow supplementation. This increase tended to be (P < 0.06) less dramatic for cows fed HCS diets (69.1, 79.6, and 85.7% for 0, 2, and 4% tallow diets, respectively) compared to cows fed HAS diets (58.3, 76.8, and 81.8% for 0, 2, and 4% tallow diets, respectively) (quadratic effect of tallow by forage interaction). This maybe attributed to the higher content of non-FA lipid in EE from alfalfa silage compared with corn silage. Concentrations of plasma glucose and plasma urea nitrogen were not affected by tallow supplementation. Shauff et al. (1992) fed four multiparous Holstein cows fitted with a ruminal cannula a TMR of 45% alfalfa haylage, 5% corn silage and 50% concentrate (DM basis). The four dietary treatments were the following: 1) control, no added fat, 2) 10% raw whole soybeans (WSB), 3) 10% WSB plus 2.5% tallow, 4) 10%WSB plus 4% tallow (DM basis). The fatty acid composition of tallow was 3.2% C14:0, 24.8% C16:0, 14.5% C18:0, 45.9% C18:1, and 5.9% C18:2. The fatty acid composition of raw WSB was 0.1% C14:0, 11.3% C16:0, 3.6% C18:0, 21.6% C18:1, and 55.4% C18:2. Intake of DM and production of milk were not affected by supplemental fat. Milk fat percentage tended (P < 0.06) to increase when fat was fed to the cows, especially when both tallow and WSB were fed (3.34, 3.41, 3.56, and 3.52% for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively). As a result of increased milk fat concentration, milk fat yield tended (P < 0.06) to increase when cows were fed fat (1.02, 1.05, 1.08, and 1.05 kg/d for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively). Yields and percentages of milk protein were not affected by treatments. Adding fat to the diets decreased the concentration of C6:0, C8:0, C10:0, C12:0, C14:0, C14:1, and C15:0 in milk fat. The milk fatty acids, C6:0, C8:0, C10:0, C12:0 and C14:0, decreased further

PAGE 29

17 when tallow was added to the diets. Concentration of C16:0 in milk fat was decreased by fat supplementation, however decreases were less when tallow was added to the diets (27.7, 23.6, 25.4, and 25.9 for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively). Concentration of C18:0 in milk fat was increased by including supplemental fat in the diet, however increases were less when tallow was added to the diets especially at 4% of the diet (8.3, 11.4, 11.0, and 10.0 g/100g for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively). The concentration of C18:1 in milk fat was increased by supplemental fat, the greatest increase occurring when both tallow and WSB were included in the diet (21.0, 25.2, 28.3, and 29.3 g/100g for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively). Supplementing fat to the diet did not affect C18:2 concentration in milk, but adding tallow with diets containing WSB decreased the C18:2 concentration in milk when compared with adding only WSB. Concentrations of total VFA in ruminal fluid were decreased by feeding fat, especially when both tallow and WSB were fed (116.4, 115.5, 108.4, and 109.1 mM for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively). Molar proportions of acetate tended to decrease (65.0, 64.1, 63.8, and 62.6 mol/100 mol for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively) and molar proportions of propionate tended to increase (18.8, 20.0, 20.4, and 21.4 mol/100 mol for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively) in ruminal fluid when fat was fed. These shifts resulted in decreased acetate to propionate ratios for cows fed fat (3.5, 3.3, 3.2, and 2.9 for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively). Ruminal fluid pH and molar proportions of butyrate, isovalerate, and valerate were not affected by treatment. Apparent total tract digestibilities of DM

PAGE 30

18 (65.9, 64.1, 63.7, and 64.1% for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively) and CP (67.3, 61.1, 61.2, and 63.1 for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively) decreased when fat was added to the diets, whereas digestibilities of ADF and NDF were not affected by fat addition. Concentrations of plasma glucose and urea nitrogen were not different among treatments. Smith et al. (1993) fed 36 Holstein cows increasing concentrations of alfalfa hay in diets containing corn silage, whole cottonseed (WCS), tallow, and yeast. Twelve dietary treatments were used in a 3 by 4 factorial design. Three corn silage to alfalfa hay ratios were fed, namely, 50:0, 37.5:12.5, and 25:25 (% of dietary DM). Four dietary concentrations of tallow and WCS were fed, namely, 0 and 0, 2.5 and 0, 0 and 12, and 2.5 and 12 (% of dietary DM). Intake of DM was not affected by tallow supplementation. Cows fed tallow produced 3.1% more milk than those not fed tallow averaged across all dietary forage ratios (23.2 vs. 22.5 kg/d). Milk fat percentage tended to be depressed when tallow was added to diets containing only corn silage (3.33 vs. 3.15%) but tended to be increased when tallow was added to diets containing both corn silage and alfalfa hay (3.27 vs. 3.58%) (tallow by corn silage vs. alfalfa hay interaction, P = 0.08). The 3.5% FCM yield (P = 0.07), milk protein yield (P = 0.09), and BW change (P = 0.06) tended to increase with tallow supplementation. The concentration of C6:0 to C15:0 fatty acids and C18:2 in milk fat were decreased when tallow was fed, whereas C16:1 and C18:1, and C18:2 were increased. Increasing alfalfa hay in the diets had no effect on milk fatty acid composition. Digestibility of DM (59.65 vs. 63.85%) and NDF (52.78 vs. 59.96%) tended to be lower with corn silage plus tallow diets than for alfalfa hay plus tallow diets. The EE digestibility was greater for tallow diets than for diets without

PAGE 31

19 tallow (88.10 vs. 79.05%). Treatments had no effect on blood urea nitrogen concentrations. Eastridge and Firkins (1991) fed five primiparous Holstein cows hydrogenated tallow fatty acids (FA) or tallow triglycerides (TG). The fatty acid composition of the hydrogenated tallow was 2.8% C14:0, 29.0% C16:0, 52.8% C18:0, and 11.2% C18:1. The fatty acid composition of the tallow triglycerides was 1.5% C14:0, 21.6% C16:0, 59.2% C18:0, and 15.6% C18:1. Fat supplements replaced a portion of the corn. Forage sources were alfalfa silage (26.3% of dietary DM) and corn silage (26.3% of dietary DM). Dietary treatments were the following: control (no supplemental fat), 2% tallow FA, 5% tallow FA, 2% tallow TG, and 5% tallow TG (% of dietary DM). Intake of DM was similar between control cows and those fed tallow. However DMI increased as tallow FA increased from 2 to 5% of the diet but decreased as tallow TG increased from 2 to 5% of the diet (fat source by fat inclusion rate interaction, P = 0.03). Milk production was greater for cows fed fat compared to controls (28.2, 30.2, 30.5, 29.3, and 30.4 kg/d for control, 2% tallow FA, 5% tallow FA, 2% tallow TG, and 5% tallow TG, respectively). Yields of 4% FCM were greater for cows fed fat compared to controls (25.7, 28.4, 30.2, 26.6, and 28.1 kg/d for control, 2% tallow FA, 5% tallow FA, 2% tallow TG, and 5% tallow TG, respectively). Percentage of milk protein was not affected by treatments. Cows fed FA produced milk of greater fat percentage than those fed TG (3.76 vs. 3.45%) and cows fed tallow at 5% tended (P = 0.10) to have greater percentages of milk fat compared to those fed tallow at 2% of dietary DM (3.69 vs. 3.52%). The apparent digestibility of DM and OM tended to be lower when diets were supplemented with fat. A greater DM digestibility depression was observed when cows

PAGE 32

20 were fed tallow in the FA form than in the TG form (62.3 vs. 66.8%). Digestibility of NDF was unchanged by treatments. Body weight was not different among treatments. Lewis et al. (1999) fed four nonlactating ruminally cannulated Holstein cows to determine the effects of dietary tallow and hay particle length. Diets contained 25% alfalfa hay 25% corn silage, and 50% concentrate (dietary DM basis). Tallow replaced a portion of the ground corn in the concentrate at 4.8% of dietary DM. Dietary treatments were the following: 1) 0% tallow, short-cut hay (1.3% > 3.3 cm), 2) 0% tallow, long-cut hay (19.6% > 3.3 cm), 3) 5% tallow, short-cut hay, or 4) 5% tallow, long-cut hay. The fatty acid composition of tallow was 3.1% C14:0, 25.2% C16:0, 15.3% C18:0, 45.1% C18:1, and 3.9% C18:2. Dry matter intake was restricted to 85% of ad libitum amounts. Total tract DM, NDF, and ADF apparent digestibilities were not affected by tallow supplementation to the diet. Total tract CP digestibility tended (P = 0.07) to increase with tallow supplementation (70.2 vs. 74.7%). No hay by tallow interactions were observed for total tract digestibilities. In situ digestibilities of TMR DM (P < 0.15), NDF (P < 0.09), and ADF (P < 0.13) at 24 h tended to be depressed by the addition of tallow. After 48 h of ruminal incubation, tallow decreased the digestibilities of DM (56.6 vs. 61.3%) and ADF (22.5 vs. 29.1%), and tended (P = 0.06) to depress NDF digestibility (27.8 vs. 32.5%). No tallow by hay length interaction after 24 or 48 h of in situ incubation were detected for DM, NDF, ADF, and CP digestibilities. Ruminal pH increased when tallow was added to the diet that contained long-cut hay, but decreased when tallow was added to the short cut hay diet (6.52, 6.59, 6.60, and 6.54 for 0% tallow, long-cut hay, 5% tallow, long-cut hay, 0% tallow, short-cut hay, and 5% tallow, short cut hay, respectively) (hay length by tallow interaction, P = 0.07). Tallow

PAGE 33

21 decreased ruminal concentrations of acetate (68.5 vs. 70.1 mol/100 mol), increased concentrations of propionate (17.3 vs. 15.4 mol/100 mol), increased concentrations of isobutyrate (1.2 vs. 1.0 mol/100 mol), increased concentrations of valerate (1.2 vs. 1.1 mol/ 100 mol), and decreased acetate to propionate ratio (4.0 vs. 4.6). Butyrate content in ruminal fluid was not affected by treatments. No hay length by tallow interactions for individual VFA were detected. Jenkins et al. (1998) fed Holstein cows from calving to 18 wk postpartum to determine the effects of tallow and hay particle size on lactation performance. Diets consisted of 25% alfalfa hay, 25% corn silage, and 50% concentrate (dietary DM basis). Tallow replace a portion of the corn. The fatty acid composition of tallow was 3.2% C14:0, 29.2% C16:0, 24.7% C18:0, 62.2% C18:1, and 2.5% C18:2. Dietary treatments were the following: 1) 0% tallow, long-cut hay (19.6% > 3.3 cm), 2) 0% tallow, short-cut hay (1.3% > 3.3 cm), 3) 5% tallow, long-cut hay, and 4) 5% tallow, short-cut hay. Intake of DM was unchanged by tallow supplementation. Milk yield was greater for cows fed tallow compared to cows not fed tallow (36.5 vs. 33.2 kg/d). Milk fat percentage tended (P = 0.12) to decrease with tallow supplementation (3.19 vs. 3.39%). Milk protein percentage was reduced by the addition of tallow (2.97 vs. 3.11%). As a result, energycorrected milk production was increased when tallow was added to diets containing short-cut hay (35.0 vs. 30.9 kg/d) but was unchanged when added to diets containing long-cut hay (33.5 vs. 33.5 kg/d) (tallow by hay length interaction). A tendency (P = 0.10) for an interaction of tallow by hay particle length was observed for fat yield in that tallow had no effect on fat yield when added to the long-cut hay (1.13 vs. 1.16 kg/d) but milk fat yield increased when tallow was added to the short-cut hay (1.18

PAGE 34

22 vs. 1.04 kg/d). Protein yield however was increased by the addition of tallow (1.09 vs. 1.01 kg/d). Samples of ruminal fluid were collected via stomach tube twice during the 18 wk study. No effect of tallow or hay particle size was detected on molar proportions of ruminal VFA. Body weight change tended (P = 0.15) to be greater for cows fed tallow than for cows fed without tallow (41.2 vs. 26.7 kg/18 wk). Adams et al. (1995) fed forty multiparous and primiparous Holstein cows 12 dietary treatments arranged in a 3 x 4 factorial design. The four forage treatments were the following: 1) 45% corn silage (CS), 2) 33.75% corn silage and 11.25% alfalfa hay (CS + AH), 3) 33.75% corn silage and 11.25% bermudagrass hay (CS + BH), and 4) 33.75% corn silage and 11.25% cottonseed hulls (CS + CSH) (dietary DM basis). The three fat treatments were the following: 1) no added fat, 2) 12.5% whole cottonseed (WCS), and 3) 2.5% tallow. The fatty acid composition of tallow was 2.7% C14:0, 23.6% C16:0, 16.5% C18:0, 43.7% C18:1, and 5.0% C18:2. Cows fed tallow produced more milk than those fed WCS but not any more than cows unsupplemented with fat (26.4, 25.4, and 26.5 kg/d for tallow, WCS, and unsupplemented cows, respectively). Addition of fat had no effect on DMI, milk yield, milk protein percentage, milk fat percentage, or BW change, however, when tallow was the source of fat, milk yield increased when compared to yields of cows fed WCS (26.4 vs. 25.4 kg/d). Milk fat % was decreased by addition of fat to CS (3.44 vs. 3.65%) or AH (3.39 vs. 3.69%) diets but milk fat was increased with fat addition to BH diets (3.53 vs. 3.37%) ((fat vs. no fat) by (BH vs. AH + CS) interaction, P = 0.036). Milk protein percentage of cows fed BH was lower when fed tallow than when fed WCS (2.98 vs. 3.19%) whereas milk protein

PAGE 35

23 percentage of cows fed CS + AH or CS alone was lower when fed WCS than when fed tallow (3.00 vs. 3.09%) ((tallow vs. WCS) by (BH vs. AH + CS interaction), P = 0.038). Drackley and Elliott (1993) fed four Holstein cows partially hydrogenated tallow (PHT) at 0, 2, 4, and 6% of dietary DM. Tallow replaced ground shelled corn. Diets contained 3.3, 5.1, 7.3, and 9.0% total fatty acids. The fatty acid composition of the PHT was 1.6% C14:0, 26.9% C16:0, 39.2% C18:0, 29.9% C18:1, and no detected C18:2. Milk production, milk fat yield, milk protein yield, and DMI were not affected by PHT. However percentage of milk protein was decreased in cows fed PHT when compared to control cows (3.02, 2.82, 2.86, and 2.85% for cows fed 0, 2, 4, and 6% PHT diets). Percentages of short and medium-chain fatty acids in milk fat decreased linearly, whereas percentages of C18:1 increased with increasing dietary PHT (18.8, 23.1 24.8 and 27.5 g/100 g of fat for cows fed 0, 2, 4, and 6% PHT diets). Ruminal pH, molar concentrations of VFA, and acetate to propionate ratio did not differ among treatments. Total tract apparent digestibilities of DM, OM, NDF, ADF, and ether extract were not affected by feeding PHT. Elliott et al. (1993) fed four ruminally fistulated lactating Holstein cows diets containing high oil corn (HOC) grain and tallow. Cows were fed diets of alfalfa haylage and concentrate (37:63, DM basis). The fatty acid composition of tallow was 3.2% C14:0, 24.8% C16:0, 14.5% C18:0, 45.9% C18:1, and 5.9% C18:2. The fatty acid composition of the high oil corn was 13.4% C16:0, 2.2% C18:0, 29.5% C18:1, and 51.4 C18:2. Treatments were the following: 1) control, no added fat, 2) high oil corn grain replacing regular corn grain, 3) high oil corn grain plus 2.5% tallow, and 4) high oil corn grain plus 5% tallow (dietary DM basis). Dry matter intake was not affected by

PAGE 36

24 supplementing fat, although DMI tended (P = 0.10) to be lower when cows were fed the diet containing HOC and 5% tallow (27.2, 27.1, 26.8, and 23.8 kg/d for control, HOC, HOC+ 2.5% tallow, and HOC + 5.0% tallow). Milk production was not different among treatments. Percentage of protein in milk was lower when cows were fed diets containing fat and tended (P = 0.13) to be lower for cows fed diets containing tallow compared with diets containing only HOC (3.04, 2.98, 2.87, and 2.80% for control, HOC, HOC+ 2.5% tallow, and HOC + 5.0% tallow). Milk fat percentage tended (P = 0.07) to be lower when cows were fed diets containing tallow (3.30, 3.33, 3.06, and 2.82% for control, HOC, HOC+ 2.5% tallow, and HOC + 5.0% tallow), although yields of milk fat were not different among treatments. Total VFA concentrations in ruminal fluid were lower when cows were fed diets containing fat and were lower when cows were fed the HOC plus 5% tallow diet compared with the HOC plus 2.5% tallow diet (133.4, 128.3, 129.2 and 122.0 mM for control, HOC, HOC+ 2.5% tallow, and HOC + 5.0% tallow). The molar proportion of acetate decreased (60.5, 61.8, 60.3,and 59.4 for control, HOC, HOC+ 2.5% tallow, and HOC + 5.0% tallow) and the molar proportion of propionate tended (P = 0.10) to increase (26.7, 25.7, 26.7,and 27.5 for control, HOC, HOC+ 2.5% tallow, and HOC + 5.0% tallow) in ruminal fluid when cows were fed diets containing tallow. Molar proportions of isovalerate were increased when cows were fed the 5% tallow diet. Ruminal pH and molar proportions of butyrate and valerate were not altered by treatment. Total tract apparent digestibilities of DM, ADF and NDF were not different among treatments. Pantoja et al. (1996) fed fifty lactating Holstein cows tallow or PHT to observe the effect of fats varying in degree of saturation. Diets contained 50% forage (50:50 alfalfa

PAGE 37

25 and corn silages, DM basis). The fatty acid composition of tallow was 2.3% C14:0, 22.7% C16:0, 17.8% C18:0, 38.8% C18:1, and 3.2% C18:2. The fatty acid composition of PHT was 1.5% C14:0, 23.0% C16:0, 52.2% C18:0, 14.5% C18:1, and no detectable C18:2. Dietary treatments were a basal diet (control) with no added fat (2.9% EE) and four diets with 5% added fat from tallow, tallow plus PHT in a 2:1 proportion, tallow plus PHT in a 1:2 proportion, and PHT. Dry matter intake tended (P = 0.07) to be lower for cows fed diets supplemented with fat than for those fed the control diet; however DMI increased linearly with increased degree of fat saturation (25.2, 23.1, 23.8, 24.8, and 24.7 kg/d for control, tallow, tallow + PHT, PHT + tallow, and PHT, respectively). Milk production increased due to fat supplementation (35.6, 40.6, 36.9, 39.3, and 38.0 kg/d for control, tallow, tallow + PHT, PHT + tallow, and PHT, respectively). Milk fat percentage was not affected by fat supplementation when compared to controls, but cows fed increasing amounts of PHT had increasing concentrations of milk fat (3.63, 3.17, 3.48, 3.56, and 3.77% for control, tallow, tallow + PHT, PHT + tallow, and PHT, respectively). Milk protein percentage was unchanged by supplemental fat when compared to the control diet, however cows fed PHT had a higher milk protein percentage than did cows fed tallow (3.05, 2.86, 3.03, 2.98, and 3.02% for control, tallow, tallow + PHT, PHT + tallow, and PHT, respectively). Cows fed the control diet lost more BW than did cows supplemented with fat, but no effect of fat source on BW change was detected. Pantoja et al. (1994) utilized six primiparous lactating Holstein cows that were cannulated in the rumen, duodenum and ileum. Forage consisted of a 60:40 mix of corn and alfalfa silages. Six dietary treatments were the following: 1) control (C) with no

PAGE 38

26 added fat, 20% soyhulls (SH), and 40% forage, 2) 5% PHT, 20% SH, and 40% forage (PHT-SH), 3) 5% tallow, 20% SH, and 40% forage (tallow-SH), 4) 5% blend of tallow and canola oil (TC), 20% SH, and 40% forage (TC-SH), 5) 5% TC, no SH, and 40% forage [(LF) low forage] (TC-LF), and 6) 5% TC, no SH, and 60% forage [(HF) high forage] (TC-HF). The fatty acid composition of PHT was 2.2% C14:0, 26.7% C16:0, 52.6% C18:0, 14.2% C18:1, and no detectable C18:2. The fatty acid composition of tallow was 2.5% C14:0, 24.8% C16:0, 1.1% C18:0, 43.8% C18:1, and 4.9% C18:2. The fatty acid composition of TC was 1.3% C14:0, 14.9% C16:0, 9.6% C18:0, 49.6% C18:1, and 14.6% C18:2. Dry matter intake was not affected by inclusion of supplemental fat in diets when compared to the control diet, but DMI decreased linearly as fat unsaturation increased (19.8, 20.8, 18.8, and 17.8 kg/d for C, PHT-SH, tallow-SH, and TC-SH, respectively). Milk fat production and percentage were similar for cows on C or fat-supplemented diets. Milk protein percentage was reduced by fat supplementation (3.06, 2.91, 2.98, and 2.82 for C, PTH-SH, tallow-SH, and TC-SH, respectively). Ruminal pH was not affected by fat supplementation. The different percentages of effective fiber in TC diets (TC-LF, TC-SH, and TC-HF) did not influence the pH of the ruminal fluid. Total VFA concentration decreased with fat supplementation when compared to the control diet. The molar percentages of acetate, propionate, butyrate, or branched-chain VFA were not affected by fat supplementation. Ruminal acetate: propionate was higher when soyhulls replaced forage NDF because of the higher digestibility of soyhulls in the rumen and total tract. Kinetics of in situ NDF digestion of alfalfa silage and SH were not influenced by fat supplementation or fat saturation. Lag time (2.1, 0.6, and 1.7 h for TC-LF, TC-SH, and TC-HF, respectively) as well as residual alfalfa silage NDF (38.5,

PAGE 39

27 37.2, 36.9% for TC-LF, TC-SH, and TC-HF, respectively) responded in a quadratic manner with percentage of effective fiber in TC diets. Cows fed TC-LF had a longer lag time and a greater residual NDF than did cows fed TC-SH or TC-HF. Wu et al. (1993) fed twenty-four Holstein cows in their midlactation a diet consisting of 39% alfalfa hay, 7.2% whole cottonseed, 5.1% cottonseed hulls and 48% concentrate (DM basis). Dietary treatments were control (C) with no supplemental fat, 2) 2.5% tallow, 3.0% Ca salts of palm fatty acids (CS), or 2.5% prilled fatty acids (PF) (dietary DM). The fatty acid composition of tallow was 3.8% C14:0, 29.1% C16:0, 15.9% C18:0, 44.4.2% C18:1, and 2.7% C18:2. The fatty acid composition of CS was 1.5% C14:0, 51.5% C16:0, 4.1% C18:0, 35.5% C18:1, and 7.4% C18:2. The fatty acid composition of PF was 3.4% C14:0, 45.7% C16:0, 42.8% C18:0, 7.1% C18:1, and no detectable C18:2. Dry matter intake did not differ among treatments. Milk yields were increased by supplemental fat (31.6, 33.9, 32.9, and 34.2 kg/d for C, tallow, CS, and PF, respectively). Milk fat percentage did not differ among treatments, but fat yields were greater for the cows receiving the fat supplements (1.02, 1.10, 1.11, and 1.15 kg/d for C, tallow, CS, and PF, respectively). Milk protein percentage was lower for cows receiving the fat supplements (3.13, 3.05, 2.97, and 3.01% for C, tallow, CS, and PF, respectively). Supplementation of dietary fat increased the percentages of C16:0 and C18:0 but decreased the percentages of C6:0 to C14:0 in milk fat. Plasma glucose concentrations were not affected by fat supplementation. Apparent digestibilities of DM, CP, ADF and NDF were not affected by overall fat supplementation. However, DM (64.4, 62.8, and 61.8%) and ADF (37.0, 32.1, and 30.9%) digestibilities were greater for diets containing tallow compared to those containing CS or PF.

PAGE 40

28 Markus et al. (1996) fed eighteen primiparous and thirty-one multiparous lactating Holstein cows tallow or whole sunflower seeds. Diets contained 12% corn silage, 14% alfalfa silage, 9% alfalfa hay, and 65% concentrate based on barley. The experimental diets were the following: 1) control at 1.8% EE, 2) 2.7% tallow, and 3) 7.1% whole sunflower seeds (dietary DM basis). Dry matter intake of cows was not influenced by tallow or whole sunflower seeds. Mean production of milk and 4% FCM were not affected by treatments (34.4, 35.5, and 34.6 kg/d and 30.0, 31.6, and 29.9 kg/d for control, tallow and sunflower, respectively). The production and concentrations of milk protein and fat were not influenced by supplemental fat. Concentrations of the C6:0 to C16:0 fatty acids in milk fat were lower compared to that coming from cows fed the control diet. Tallow supplementation resulted in greater concentrations of C18:0, C18:1, and C20:0 fatty acids in milk fat compared to those from cows fed the control diet. The concentrations of individual or total VFA in the ruminal fluid were not influenced by feeding tallow or whole sunflower seeds. Change in BW was not influenced by supplemental tallow or whole sunflower seeds. Onetti et al. (2001) fed fifteen ruminally cannulated midlactation Holstein cows tallow or choice white grease (CWG). The fatty acid composition of tallow was 2.8% C14:0, 24.8% C16:0, 19.8% C18:0, 42.7% C18:1, and 3.3% C18:2. The fatty acid composition of CWG was 1.4% C14:0, 23.8% C16:0, 10.9% C18:0, 47.6% C18:1, and 11.7% C18:2. Dietary treatments were 0% supplemental fat (control), 2% tallow, 2% CWG, 4% tallow, and 4% CWG (DM basis). The forage to concentrate ratio was 50:50 (DM basis). Corn silage was the sole forage source. Fat replaced part of the cracked corn and soybean meal in the concentrate portion the fat-supplemented diets.

PAGE 41

29 Compared with the control diet, the dietary NDF concentration was 4 and 7 percentage units lower for the 2 and 4% fat diets (34.0 for control, 29.95 for 2% fat diets and 27.25 for 4% fat diets) probably because a lower inclusion of soybean hull NDF with each increase in added fat. Fatty acid concentration was 3.0% for control, 4.3 and 4.4% for 2% tallow and CWG, and 6.9 and 5.6% for the 4% tallow and CWG treatments. Cows fed supplemental fats consumed 2 kg/d less DM than control cows (24.2 vs. 26.3 kg/d). Cows fed the 4% fat diets tended (P = 0.08) to consume less DM than those fed the 2% fat diets (23.7 vs. 24.6 kg/d). Milk production decreased with fat supplementation and was most pronounced for cows receiving 4% fat in the diet (42.3, 41.1 and 38.1 kg/d for control, 2% fat, and 4% fat, respectively). The same response was observed for 4% FCM yield (37.8, 36.5 and 31.8 kg/d for control, 2% fat, and 4% fat respectively). Cows consuming fat-supplemented diets produced milk of lower fat percentage than cows fed the control diet (2.9 vs. 3.3%) and less milk fat than cows fed the control diet (1.1 vs. 1.4 kg/d). Production of milk fat was decreased when CWG increased from 2 to 4% of diet (1.20 vs. 1.08 kg/d), but was unchanged when tallow increased from 2 to 4% of diet (1.10 vs. 1.12 kg/d) (fat source by fat concentration interaction). Milk fat percentage increased when tallow increased from 2% to 4% of diet (2.83 vs. 3.00%), but decreased when CWG increased from 2 to 4% of diet (2.93 vs. 2.85%) (fat source by fat concentration interaction). Milk protein yield decreased with the increased concentration of supplemental fat (1.33 and 1.26 kg/d for the 2 and 4% fat treatments, respectively). Milk protein percentage tended to increase (P < 0.06) with the level of fat supplementation (3.29 vs. 3.33% for the 2 and 4% fat treatments, respectively). Relative percentage of milk fatty acids having 14 or fewer carbons was decreased with

PAGE 42

30 supplemental fat (24.0, 19.5, and 18.2 g/100 g of fatty acids for control, 2% fat and 4% fat, respectively). This reduction tended (P < 0.09) to be more pronounced in milk from cows fed CWG than those fed tallow (18.2 vs.19.2 g/100 g of fatty acids). Including fat in the diets increased the milk fat concentration of C18:0 (8.4 vs. 9.1 g/100 g of fatty acids) and this increment was more marked for cows fed CWG that for those fed tallow (9.3 vs. 9.0 g /100 g of fatty acids). The C18:1 percentage in milk fat increased when fat was supplemented compared to the control group (29.1 vs. 24.9 g/100 g of fatty acids). Concentrations of C18:2 (5.10 vs. 3.75 g/100 g of fatty acids) and C18:3 (0.35 vs. 0.25 g/100 g of fatty acids) were decreased when fat was added to the diets. Tallow supplementation decreased C18:2 to a greater extent than did CWG (3.6 vs. 3.9 g/100 g of fatty acid for tallow and CWG, respectively). The proportion of cis 9, trans-11 conjugated linoleic acid (CLA) was decreased (0.47 vs. 0.40 g/100 g of fatty acids), whereas the proportion of the trans-10, cis 12 CLA isomer was not affected when supplemental fat was fed. Concentration of milk fat C18:1 isomers, both cis-9 and cis-11 isomers, were increased by fat supplementation. The trans-10 isomer increased when fat was added to the diets, and it was higher in milk fat from CWG-fed cows than from tallow-supplemented cows (1.20, 2.19 and 1.98 g/100 g of fatty, respectively). The trans-11 isomer concentration of milk fat decreased with fat supplementation and was lower for cows fed CWG than for those fed tallow (0.73, 0.42 and 0.52 g/100 g of fatty acid, respectively). Adding supplemental fat at 4% of dietary DM reduced trans-11 proportion relative to the 2% level of fat supplementation. Ruminal fluid pH and total VFA concentration were not affected by fat supplementation. The molar proportion of ruminal acetate decreased (58.0 vs. 52.0 mol/100 mol), and the molar proportion of propionate

PAGE 43

31 increased (22.9 vs. 30.4 mol/100 mol) when feeding supplemental fat. The acetate to propionate ratio (A:P) decreased due to fat supplementation (2.56 vs. 1.75 mol/100 mol). The A:P decreased at the 4% fat supplementation rate relative to that of the 2% fat treatment (1.6 vs. 1.9 mol/100 mol). Fat supplementation reduced protozoa numbers per ml of rumen fluid and the reduction was most severe at the highest level of fat supplementation (7.5, 4.3, and 2.2 x 10 5 /ml for control, 2% fat and 4%fat, respectively). Fat source did not influence protozoa numbers in this experiment. Grummer et al. (1993) fed sixteen multiparous Holstein cows diets containing increasing increments of tallow. The fatty acid composition of tallow was 2.9% C14:0, 26.8% C16:0, 17.6% C18:0, 44.1% C18:1, and 4.0% C18:2. Treatments were 0, 1, 2 or 3% of dietary DM as supplemental tallow. Total mixed rations contained 33% alfalfa silage, 12% corn silage, 14% whole roasted soybeans, and 41% concentrate based on ground corn and soybean meal (DM basis). Tallow replaced part of the ground corn in the fat-supplemented diets. Dietary concentration of C14:0 to C18:3 was 5.5% for control, 6.3 for 1%, 6.9 for 2%, and 7.6 for 3% tallow diets. The dietary CP concentration was similar among treatments. Supplementation of tallow increased fatty acid intake of C14:0 to C18:3 linearly (1.46, 1.70, 1.80 and 1.98 kg/d for 0, 1, 2, and 3% supplemental tallow). Ruminal fluid pH was depressed linearly by fat supplementation (6.2, 6.1, 6.0, and 5.9 for cows fed 0, 1, 2, and 3% supplemental tallow). In situ extent of forage DM disappearance at 48 h did not differ among treatments (forage in the insitu bag was 73% alfalfa haylage and 27% corn silage). Ruminal fluid VFA concentrations were increased by dietary tallow. Molar proportions of isobutyrate and isovalerate were reduced by tallow supplementation. Butyrate concentration responded quadratically as

PAGE 44

32 tallow supplementation increased. Dry matter intake, milk yield, milk fat percentage, 3.5% FCM yield, milk fat yield, and milk protein yields were unchanged by tallow addition. Milk protein percentage decreased linearly as tallow supplementation increased (2.89, 2.89, 2.85 and 2.86% for cows fed 0, 1, 2, and 3% supplemental tallow). Weigel et al. (1997) evaluated how effects of tallow supplementation might be affected by dietary concentration and source of CP. The sources of CP were soybean meal or a by-product protein mixture containing blood meal, meat and bone meal, and corn gluten meal. Five ruminally fistulated dairy cows were fed the following five treatments: 1) control, 2) 15% CP, soybean meal, 3) 15% CP, by-product proteins, 4) 18% CP, soybean meal, and 5) 18% CP, soybean meal and by-product proteins. Diet 1 contained no tallow and diets 2 through 5 contained 3.5% tallow. Diets consisted of 28% alfalfa haylage, 22% corn silage, and 50% concentrate on a DM basis. Tallow did not affect DMI or percentages of fat and CP in milk. Dairy cows that received supplemental tallow tended (P < 0.11) to produce more milk (31.2 vs. 28.7 kg/d) compared with the controls. The fatty acid concentration of C6:0 through C16:0, C18:3, and glycerol in milk fat decreased whereas the fatty acid concentration of C17:0, C18:0, and C18:1 increased when tallow was fed. Supplemental tallow did not affect the apparent digestibility of DM, OM, CP, ADF, NDF, or EE. The ruminal fluid pH, total VFA concentration in ruminal fluid, or molar ratios of VFA were unchanged by tallow supplementation. Yield of milk, milk fat, and the percentages of fat and CP in milk were not affected by the amount or source of dietary CP. However an increase in dietary CP from 15 to 18% increased DMI (19.8 vs. 21.5 kg/d), increased the apparent digestibility

PAGE 45

33 of DM, OM, and CP, decreased ruminal fluid pH (6.03 vs. 5.97), and increased total VFA concentration (104.2 vs. 113.0 mM). Onetti et al. (2002) fed eighteen Holstein cows diets having different alfalfa silage: corn silage ratios with (2%) and without (0%) tallow (DM basis). The fatty acid composition of tallow was 3.0% C14:0, 25.1% C16:0, 19.7% C18:0, 42.1% C18:1, and 3.0% C18:2. The three dietary forage ratios were: 1) 50% corn silage, 2) 37.5% corn silage and 12.5% alfalfa silage, and 3) 25% corn silage and 25% alfalfa silage (DM basis). Interactions of dietary forage source and tallow were not detected. Dry matter intake was 0.8 kg/d lower for cows fed supplemental tallow (23.3 vs. 24.1 kg/d). Tallow supplementation increased milk production by 1.4 kg/d (37.4 vs. 36.0 kg/d). Milk fat percentage decreased with tallow (2.9 vs. 3.2%). Milk protein production was increased with supplemental tallow (1.22 vs. 1.18 kg/d), but milk protein percentage was unchanged. The proportions of short and medium chain fatty acids (C4 to C14) in milk fat decreased with supplemental tallow. The proportion of C16:0 and C18:3 in milk fat was depressed whereas the concentration of C18:1 in milk fat was increased when tallow was added to the diet. Tallow supplementation increased the concentration of all the trans C18:1 isomers in milk fat except for trans-11 and trans-16 which were not affected by tallow addition. Concentration of trans-10, cis-12 CLA was greater in milk fat from tallow-supplemented cows when compared with milk fat from cows that did not receive tallow. No effect of supplemental tallow on ruminal fluid pH was observed. The molar proportion of acetate decreased whereas that of propionate, butyrate, and valerate were not affected when tallow was included in the diets. Molar proportions of isovalerate and isobutyrate were increased when tallow was fed. No effect of supplemental tallow on in

PAGE 46

34 situ DM and NDF disappearance was observed (data not reported). Increasing the proportion of alfalfa silage increased DMI, milk fat percentage and milk fat yield regardless of the fat content of the diet. In experiment 1, Bateman et al. (1996) fed forty-eight lactating Holstein cows a low (32.7%) or high (40.5%) NDF diet containing tallow at 0 or 0.45 kg/d during a winter and summer season. The NDF content of the diet was manipulated by substitution of corn and soybean meal with the fibrous by-product feeds of corn gluten feed, soyhulls, wheat middlings, and high moisture whole ear corn. The DMI of cows fed the low NDF diets in winter decreased when tallow was added (25.2 vs. 22.6 kg/d) but was unchanged when tallow was added to high NDF diets. Tallow did not affect DMI during the summer. Tallow did not influence milk production or milk fat percentage during summer or winter. Milk protein percentage was reduced by addition of tallow during winter for cows fed low and high NDF diets (3.30%, 3.17%, 3.22%, and 3.09% for low NDF no fat, low NDF added fat, high NDF no fat, and high NDF added fat diets, respectively). Inclusion of tallow in diets increased concentration of plasma NEFA during the winter (0.19, 0.22, 016, and 0.21 mM for low NDF no fat, low NDF added fat, high NDF no fat, and high NDF added fat diets, respectively) and summer (0.45, 0.51, 0.46, and 0.54 mM for low NDF no fat, low NDF added fat, high NDF no fat, and high NDF added fat diets, respectively). Concentration of plasma glucose increased with addition of tallow during winter (74.2, 75.3, 72.5, 78.3 mg/dl for low NDF no fat, low NDF added fat, high NDF no fat, and high NDF added fat diets, respectively) and in summer (57.5, 63.8, 57.7,and 63.4 mg/dl for low NDF no fat, low NDF added fat, high NDF no fat, and high NDF added fat diets, respectively). Palmquist and Jenkins (1980) noted in their review that

PAGE 47

35 high fat diets can result in an inability of insulin to stimulate glucose utilization by tissues, thus causing an increase in plasma glucose concentrations. In experiment 2, Bateman et al. (1996) fed four Holstein cows the same four diets described above during winter to study the effects of tallow on ruminal fermentation. Inclusion of tallow in low NDF diets decreased the proportions of acetic acid and increased proportions of propionic acid. Addition of tallow to high fiber diets increased acetic acid concentration and decreased propionic acid concentration. No differences in butyric acid were observed. The A:P ratio decreased when tallow was added to low fiber diets but increased when tallow was added to high fiber diets (tallow by NDF interaction). In summary, when tallow was used as a source of supplemental fat for lactating dairy cows, DMI decreased (Ruppert et al., 2003; Onetti et al., 2001; Onetti et al., 2002) or was unchanged (Shauff et al., 1992; Smith et al., 1993; Eastridge and Firkins, 1991; Jenkins et al., 1998; Adams et al., 1995; Elliot et al., 1993; Wu et al., 1993; Markus et al., 1996; Grummer et al., 1993; Weigel et al., 1997; Bateman et al., 1996; Jones et al., 2000). The depression observed in DMI was mainly due to the unsaturated fatty acid content in fat sources, as observed in Pantoja et al. (1994) who reported that DMI decreased with increased degree of unsaturation of the fat source. Milk production was not affected (Ruppert et al., 2003; Drackley and Elliot, 1993; Elliot et al., 1993; Markus et al., 1996; Bateman et al., 1996; Jones et al., 2000), increased (Smith et al., 1993; Eastridge and Firkins, 1991; Jenkins et al., 1998; Pantoja et al., 1996; Wu et al., 1993; Weigel et al., 1997; Onetti et al., 2002), or decreased (Onetti et al., 2001; Grummer et al., 1993) when tallow was supplemented to the diet. Milk fat concentration was increased

PAGE 48

36 (Shauff et al., 1992), depressed (Ruppert et al., 2003; Jenkins et al., 1998; Elliot et al., 1993; Onetti et al., 2001; Onetti et al., 2002), or unchanged (Pantoja et al., 1996; Pantoja et al., 1994; Wu et al., 1993; Markus et al., 1996; Weigel et al., 1997; Grummer et al., 1993; Bateman et al., 1996) by tallow addition to the diet. The composition of milk fat was altered as tallow was supplemented to diets. Proportions of shortand medium-chain FA in milk (C6:0 to C16:0) decreased (Ruppert et al., 2003; Shauff et al., 1992; Smith et al., 1993; Markus et al., 1996; Onetti et al., 2001 Onetti et al., 2002) whereas long-chain fatty acids (C16:0 to C18:2) increased (Smith et al., 1993; Markus et al., 1996; Onetti et al., 2002) by feeding tallow. Milk protein percentage increased (Onetti et al., 2001), decreased (Ruppert et al., 2003; Jenkins et al., 1998; Elliot et al., 1993; Pantoja et al., 1994; Wu et al., 1993), or was not affected (Shauff et al., 1992; Eastridge and Firkins, 1991; Adams et al., 1995; Drackley and Elliot, 1993; Pantoja et al., 1996; Markus et al., 1996; Grummer et al., 1993; Weigel et al., 1997; Onetti et al., 2002) by tallow inclusion in the diet. Plasma glucose concentration was unchanged (Ruppert et al., 2003; Shauff et al., 1992; Wu et al., 1993) or increased (Bateman et al., 1996) with addition of tallow whereas plasma urea nitrogen concentration was unaffected (Shauff et al., 1992). Ruminal fluid pH was not affected (Ruppert et al., 2003; Shauff et al., 1992; Pantoja et al., 1994; Onetti et al., 2001; Weigel et al., 1993; Onetti et al., 2002) or decreased (Grummer et al., 1993). Total VFA concentration was unchanged (Ruppert et al., 2003; Markus et al., 1996; Onetti et al., 2001; Weigel et al., 1997), decreased (Elliot et al., 1993; Pantoja et al., 1994), or increased (Grummer et al., 1993), and protozoa number per milliliter of rumen fluid decreased (Onetti et al., 2001) with supplemental tallow. Tallow decreased ruminal molar proportions of acetate and increased propionate (Ruppert et al.,

PAGE 49

37 2003; Shauff et al., 1992; Lewis et al., 1999; Elliot et al., 1993; Onetti et al., 2001). Others reported no effect (Pantoja et al., 1994; Markus et al., 1996). Molar proportions of isobutyrate and isovalerate were reduced (Grummer et al., 1993) or increased (Onetti et al., 2002) by tallow supplementation. Total tract apparent digestibilities of DM were not affected (Ruppert et al., 2003; Lewis et al., 1999; Elliot et al., 1993; Weigel et al., 1997), were decreased (Shauff et al., 1992; Eastridge and Firkins, 1991), or increased (Wu et al., 1993). That of CP was decreased (Shauff et al., 1992), unchanged (Ruppert et al., 2003; Weigel et al., 1997), or increased (Lewis et al., 1999). Total tract apparent digestibility of ADF was not affected (Shauff et al., 1992; Lewis et al., 1999; Elliot et al., 1993; Weigel et al., 1997) or were increased (Wu et al., 1993), whereas that of NDF was unchanged (Shauff et al., 1992; Eastridge and Firkins, 1991; Lewis et al., 1999; Elliot et al., 1993; Weigel et al., 1997). Total tract apparent digestibility of EE was increased (Ruppert et al., 2003; Smith et al., 1993) or unchanged (Weigel et al., 1997) by tallow supplementation. In situ DM digestibility of DM and NDF were decreased (Eastridge and Firkins, 1991) by tallow. Effects of Tallow and Fish Oil in Ruminant Diets Jones et al. (2000) fed four midlactation Holstein cows one of four diets that contained 3% added fat (DM basis). Diets consisted of 30% corn silage, 29% alfalfa silage, 7.4% alfalfa hay, 30.6% corn grain and soybean meal-based concentrate, and 3% fat (DM basis). Supplemental fat was 100% tallow, 67:33 tallow:fish oil, 50:50 tallow:fish oil, and 33:67 tallow:fish oil. The fish oil was Menhaden fish oil. Treatments did not affect DMI, milk yield, or milk fat or protein concentration. The proportion of fatty acids C18:0 and cis-C18:1 decreased and trans-C18:1, conjugated linoleic acid, C18:3, C20:4, and C20:5 increased in the milk fat with increasing fish oil in the diet.

PAGE 50

38 Jones et al. (1998) fed lactating Holstein cows diets containing 0% supplemental fat, 3.2% tallow, 2.6% fish oil, or 1.9% fish oil treated with ethylamide (DM basis). Diets consisted of 23% alfalfa silage, 20% corn silage, and 57% concentrate (DM basis). Fish oil decreased DMI (21.0, 19.3, 16.1, and 17.1 kg/d for 0% fat, 3.2% tallow, 2.6% fish oil, and 1.9% treated fish oil, respectively). Milk and milk component yields were decreased by all fat supplements. Fat supplements decreased proportions of milk fatty acids C6:0 to C14:0 in milk fat, the proportions of these were greater for cows fed fish oil than for those fed tallow. Fat supplements increased concentrations of C16:1, C17:0, C18:1t, CLA, and all long chain PUFA in milk fat. Compared with tallow, fish oil increased proportions of all unsaturated fatty acids except C18:1c, which was lower. Compared with control, fish oil decreased C18:0 and C18:1c and increased C18:1t in milk fat. Effects of Fish Oil in Ruminant Diets Donovan et al. (2000) fed twelve multiparous lactating Holstein cows Menhaden fish oil. On a DM basis, diets contained 25% corn silage, 25% alfalfa hay, and 50% of concentrate mix. Fish oil was supplemented at 0, 1, 2, and 3% of dietary DM. Dry matter intake showed a quadratic response, decreasing at the 2 and 3% level (28.7, 29.0, 23.5, and 20.4 kg/d for cows fed 0, 1, 2, 3% fish oil diets, respectively). Milk yield increased for cows fed the 1% fish oil diet, but decreased thereafter with the further addition of fish oil (31.7, 34.2, 32.3, and 27.4 kg/d for cows fed 0, 1 2, 3% fish oil diets, respectively). The concentration of fat in milk decreased with increasing intake of fish oil (3.0, 2.8, 2.4 and 2.3% for cows fed 0, 1, 2, 3% fish oil diets, respectively). The fatty acid concentrations in milk fat were altered by fish oil. The proportions of short-chain fatty acids (C4:0 to C12:0) decreased, long-chain fatty acids increased, and the milk fat

PAGE 51

39 was more unsaturated. Milk protein percentages were similar among treatments. Diets had no effect on BW change. Cant et al. (1997) fed four primiparous Holstein cows diets of 45% orchardgrass silage and 55% concentrate (DM basis). The four dietary treatments were a basal diet (control), the basal diet plus 14.5 mg/kg of monensin sodium (M), 2% red fish oil (FO), and a combination of red fish oil and monensin (FO + M). Intake of DM was reduced when cows were fed fish oil. An interaction with monensin depressed DM intakes further (17.5, 17.3, 15.7, 14.2 kg/d for control, M, FO, and FO + M, respectively). Milk yield was not affected by M or FO treatments. Milk fat concentration was reduced by feeding fish oil (3.90, 2.74, 2.53% for control, FO, and FO + M, respectively), as well as milk fat yield (0.89, 0.57,and 0.52 kg/d). Feeding fish oil increased the concentration of 20and 22-carbon fatty acids in milk fat. Whitlock et al. (2002) fed eight multiparous Holstein and four multiparous Brown Swiss cows diets containing 2% supplemental fat. The supplemental fats were menhaden fish oil (FO) or extruded soybeans (ESB). Diets consisted of a 50:50 ratio of forage to concentrate (DM basis). The forage sources were 25% corn silage and 25% alfalfa hay. The concentrate was mainly cracked corn and soybean meal. In the fat-supplemented diets, the FO replaced a portion of the cracked corn and ESB replaced a portion of the soybean meal. The four dietary treatments were 0% supplemental fat (control diet), 2% added menhaden FO, 2% ESB, and 1% added FO plus 1% added ESB (DM basis). Intake of DM (24.3, 21.6, 24.5, and 22.5 kg/d), milk production (32.1, 29.1, 34.6, and 31.1 kg/d), and milk fat concentration (3.51, 2.79, 3.27, and 3.14%) were lower for cows that consumed FO, especially the 2% fish oil diet (control, FO, ESB, and FO + ESB,

PAGE 52

40 respectively). Milk protein concentration was unchanged by dietary treatments. Concentration of transvaccenic acid and cis-9, trans 11 CLA in milk fat increased with feeding of FO, ESB, and FO + ESB. In experiment 1, Doreau and Chilliard (1997) used six multiparous lactating Holstein dairy cows fitted with permanent cannulae of the rumen and proximal duodenum. Diets consisted of 70% maize silage and 30% concentrate (DM basis). The three treatments were no oil infusion (C), continuous ruminal infusion of 300 ml (276 g) of menhaden fish oil (R), and a continuous duodenal infusion of 300 ml of fish oil (D). Ruminal oil infusion decreased DM intake compared to the control cows (16.2 vs. 19.8 kg/d). The apparent digestibilities of DM (73.5 vs. 70.2%) and OM (75.5 vs. 72.6%) and NDF (64.5 vs. 59.4%) were greater for treatment R than for C. Ruminal pH was unaffected by infusions. Ruminal oil infusion decreased the acetate proportion and the A:P ratio and increased the propionate and isovalerate proportions. The butyrate and valerate proportions were only decreased by the oil infusion at 1500 h. No effects on ruminal VFA were observed with duodenal infusions. In experiment 2, Doreau and Chilliard (1997) fed six lactating Holstein cows a diet consisting of 65% maize silage and 35% concentrate (DM basis). The three dietary treatments were 0 ml menhaden FO (C), 200 ml (185 g) of menhaden FO (L), and 400 ml (370 g) of menhaden FO (H). Intake of DM was lower for treatment H than for treatments C and L (19.2, 19.0, and 15.5 kg/d). Cows on treatment L had increased apparent DM (69.9 vs. 66.8%) and ether extract (79.8 vs. 63.2%) digestibilities when compared to the controls. Cows on treatment H had increased apparent DM (71.2 vs. 66.8%), OM (73.5 vs. 69.2%), NDF (52.7 vs. 47.0%), and ether extract (85.3 vs. 63.2%)

PAGE 53

41 digestibilities when compared to the controls. When 400 ml of FO were added to the diet, the proportions of acetate and acetate:propionate ratio decreased while the proportion of propionate increased in the ruminal fluid. Chilliard and Doreau (1997) fed eight lactating Holstein cows diets of 65% forage and 35% concentrate (DM basis).The source of forage was maize silage. The four dietary treatments were 1) no supplement (control), 2) 300 ml of menhaden FO, 3) 20 g of rumen-protected methionine, and 4) 300 ml of FO plus 20 g of rumen-protected methionine. Incorporation of FO in the diet decreased DM intake on average (19.2 vs. 17.8 kg/d for control and fish oil respectively). No differences in live weight were detected due to treatment. Addition of FO increased milk yield by 1.6 kg/d on average when compared to the controls (26.5 vs. 28.1 kg/d). Fish oil supplementation sharply decreased milk fat concentration by an average by 1.3% when compared to the control cows (3.86 vs. 2.54 %). Keady et al. (2000) fed fifty Holstein-Friesian dairy cows grass silage and either 5 or 10 kg/d of concentrate. The dietary treatments were intakes of 0, 150, 300, or 450 g/d of herring/markerel fish oil. Fish oil supplementation decreased DMI only at the 450 g/d rate (16.0, 16.6, 15.7 and, 14.3 kg/d for 0, 150, 300, and 450 g/d of FO). Supplementation of fish oil also decreased the concentration of milk protein by 0.09% for each 100 g increase in fish oil supplementation (3.27, 3.20, 3.01, and 2.89% for cows fed 0, 150, 300, and 450 g/d of FO). Milk fat concentration was decreased by 15% with 450 g/d of FO (4.23, 4.04, 3.66, and 2.73% for cows fed 0, 150, 300, and 450 g/d of FO). As FO was added to the diet, milk yield increased (22.5, 25.0, 25.2, and 25.7 kg/d for cows fed 0, 150, 300 and 450 g/d of FO). As rate of FO inclusion increased, the apparent

PAGE 54

42 digestibility coefficients of DM increased (77.4, 78.5, 79.1, and 80.4 for cows fed 0, 150, 300 and 450 g/d of FO). No effect on NDF and ADF digestibility coefficients was detected. AbuGhazaleh et al. (2002) fed four fistulated primiparous lactating cows. Diets consisted of 25% corn silage, 25% alfalfa hay and 50% concentrate (DM basis). Dietary treatments were 0% supplemental fat (control diet), 2% menhaden FO, 2% added fat from extruded soybeans (ESB), and the 1% menhaden FO and 1% added fat from ESB (FO + ESB). Dry matter intake (23.0, 21.6, 22.7, and 21.6 kg/d for cows fed control, FO, ESB, and FO + ESB, respectively) was reduced when diets containing FO were fed. Milk yields were similar across all diets. Mean milk fat percentage, mean milk protein percentage, and yield were not different among cows fed the four diets. Milk fatty acid proportions of C6:0 to C14:0 were decreased. The concentrations of CLA cis-9, trans-11 (0.40, 0.88, 0.87 and 0.80 g/100 g of fatty acids for control, FO, ESB, and FO + ESB diets, respectively) and transvaccenic acid (1.02, 2.34, 2.41, and 2.06 g/100 g of FA) were increased by both fat supplements. The proportion of C18:0 FA in milk fat was not different between control and fat-supplemented diets. Milk EPA and DHA concentration were increased with FO supplements compared with the control and ESB diets (0.05, 0.24, 0.05, and 0.16 g of EPA /100 g of fatty acids and 0.01, 0.47, 0.02, and 0.29 g of DHA /100 g of fatty acids for control, FO, ESB, and FO + ESB diets, respectively). Lacasse et al. (2002) fed thirty Holstein cows in midlactation protected or unprotected fish oil. The forage sources were grass silage and maize silage fed to the cows in a TMR along with rolled barley. Fish oil was protected by a glutaraldehyde microcapsule. The four dietary treatments were the following: 1) control (no

PAGE 55

43 supplemented fish oil), 2) 3.7% unprotected fish oil (UFO), 3) 1.5% protected fish oil (L-PFH), and 4) 3.0% protected fish oil (H-PFO). Cow fed unprotected fish oil had lower feed intakes, lost more BW, and produced less milk than cows fed protected fish oil. Concentration of milk protein and milk fat were decreased by unprotected or H-PFO. Short and medium chain fatty acids (< C16) concentrations in milk fat were decreased by fish oil supplementation. Concentrations of C18:0 (6.6, 3.2, 6.1, and 4.2%) and cis9-C18:1 (16.8, 10.6, 15.6, and 12.0%) were decreased by UFO or H-PFO for control, UFO, L-PFO, and H-PFO, respectively. Concentrations of trans-C18:1 were increased by the two forms of fish oil (2.9, 9.9, 6.1, and 9.7% for control, UFO, L-PFO, and H-PFO, respectively). Concentrations of C18:2 (2.1, 3.5, 2.5, and 2.8%), C20:5 (0.04, 0.28, 0.08, and 0.17%) and C22:6 (0.08, 0.19, 0.13, and 0.15% were increased by inclusion of UFO or H-PFO in the cow diets for control, UFO, L-PFO, and H-PFO, respectively. Ahnadi et al. (2002) utilized 16 Holstein cows in midlactation to examine effects of dietary fish oil on alterations of mammary gland fatty acid metabolism. Dietary treatments were the same as reported by Lacasse et al. 2002. Mammary gland biopsies were taken from a rear quarter at the end of each period. Milk production was lower with UFO supplementation when compared to cows fed control diets (27.5, 22.2, 33.9, and 30.3 kg/d for control, UFO, L-PFO, and H-PFO respectively). Milk fat percentage (3.60, 2.60, 2.40, and 2.04%) and milk fat yield (0.98, 0.55, 0.83, and 0.63 kg/d) were decreased by fish oil addition in cows fed control, UFO, L-PFO, and H-PFO, respectively. Milk protein percentage was lower for cows fed H-PFO (3.50, 3.26, 3.23, and 3.04% for control, UFO, L-PFO, and H-PFO, respectively) but milk protein yield was not affected

PAGE 56

44 by dietary treatments. Fish oil treatments reduced the concentrations of short and medium chain fatty acids in milk fat Concentrations of C16:1 in milk fat were increased by feeding UFO and H-PFO when compared to controls (1.65, 3.88, 1.73, and 3.80% for control, UFO, L-PFO, and H-PFO, respectively). Concentrations of C18:0 were decreased, trans C18:1 and C20:5 were increased in milk fat of cows fed UFO and H-PFO, and C18:2 was increased by UFO. Cows that were fed UFO had lower mRNA abundance of acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), steroyl-CoA desaturase (SCD), and lipoprotein lipase (LPL) enzymes and supplementation of H-PFO resulted in a lower mRNA abundance of ACC, FAS, SCD but no effect on LPL when compared to control diets. Concentration of plasma glucose was not affected by fish oil supplementation. Pate (1996) fed catfish oil in a molasses-feather meal slurry to yearling beef heifers to observe the effects of addition of fat on body weight and pregnancy rate. The three dietary supplements were the following: 1) molasses-urea, 2) molasses-feather meal (13% feather meal), and 3) molasses-feather meal-catfish oil (5% fat from catfish oil). Liquid supplements were provided in open troughs. Heifers grazed bahiagrass pastures and were offered bales of starrgrass hay. No differences in intake were detected among dietary treatment groups. Average daily gain and percent pregnancy were greater when heifers were fed molasses-feather meal supplements. Percentage of pregnancy (9.5, 31.4,and 47.6% for molasses-urea, molasses-feather meal, and molasses-feather meal-catfish oil, respectively) and average daily gain were greater when catfish oil was include in the molasses-feather meal supplements.

PAGE 57

45 In summary, fish oil supplementation resulted in a reduction in DMI (Cant et al., 1997; Whitlock et al., 2002; Doreau and Chilliard, 1997; Chilliard and Doreau, 1997; Keady et al., 2000; AbuGhazaleh et al., 2002; Lacasse et al., 2002). The reduction in DMI was dependent upon the concentration of fish oil in the diet. When fish oil was supplemented at up to 1% of dietary DM, depressions in DMI were not observed. However when concentration of fish oil increased in the diet to 1.6% of dietary DM, DMI was depressed. Milk production was increased (Donovan et al., 2000; Chilliard and Doreau, 1997; Keady et al., 2000), unchanged (Cant et al., 1997; Whitlock et al., 2002; AbuGhazaleh et al., 2002), or decreased (Ahnadi et al., 2002; Lacasse et al., 2002) by feeding fish oil. Milk fat concentration decreased (Donovan et al., 2000; Cant et al., 1997; Chilliard and Doreau, 1997; Keady et al., 2000; Lacasse et al., 2002; Ahnadi et al., 2002) or was unchanged (AbuGhazaleh et al., 2002) by fish oil addition. The fatty acid concentrations in milk fat were altered by fish oil. Feeding fish oil caused the proportions of short chain fatty acids (C4:0 to C12:0) to decrease (Donovan et al., 2000; Lacasse et al., 2002; Anhadi et al., 2002; AbuGhazaleh et al., 2002), of C16:1 in milk fat to increase (Lacasse et al., 2002), and of C18:0 to decrease (Ahnadi et al., 2002) or be unchanged (AbuGhazaleh et al., 2002). Milk protein concentration was unchanged (Donovan et al., 2000; Withlock et al., 2002; AbuGhazaleh et al., 2002; Ahnadi et al., 2002) by feeding fish oil. Fish oil infusion into the rumen decreased molar proportion of acetate (Doreau and Chilliard, 1997), increased molar proportion of propionate (Doreau and Chilliard, 1997), and increased the apparent digestibility of DM (Doreau and Chilliard, 1997; Keady et al., 2000), NDF (Doreau and Chilliard, 1997) and OM (Doreau and Chilliard, 1997).

PAGE 58

CHAPTER 3 PERFORMANCE OF LACTATING HOLSTEIN COWS FED CATFISH OIL Introduction Reductions in dry matter intake and milk production occur when dairy cows are exposed to heat stress. The addition of fats to dairy cow diets during the summer period can be an excellent choice because they are energy dense, produce less heat increment, and do not cause the same detrimental effects as does the over feeding of starch (Palmquist and Jenkins, 1980). Fats can be supplied from vegetable or animal sources. The responses of the dairy cow to fat supplementation can depend on the fatty acid profile of the fat supplement and also on the type of dietary forage (Smith et al., 1993; Ruppert et al., 2003). Several studies reported that supplemental fat increased milk production (Cant et al., 1991; Cant et al., 1993; DePeters et al., 1987; Martinez et al., 1991; Donovan et al., 2000; Keady et al., 2000; Chilliard and Doreau, 1997) but also could depress DMI. The responses were dependent partially on the fat concentration in the dietary DM. In the search for fat supplements to use in dairy cow diets, preliminary work in Florida indicated that catfish oil (CFO) mixed with liquid molasses dramatically improved intake of the liquid supplement by beef cows on rangeland (F. M. Pate, personal communication). Catfish oil has not been evaluated as a feedstuff for dairy cows. Because catfish are a fresh water fish, their fatty acid profile is different from that of marine fish in that omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are in lower concentrations. This is due to the fact that 46

PAGE 59

47 pond-raised fresh water fish consume less algae, the source of omega-3 fatty acids. Feeding marine fish oil has improved milk production (Chilliard and Doreau, 1997; Keady et al., 2000) but can decrease dry matter intake (Chilliard and Doreau, 1997; Keady et al., 2000). If catfish oil can improve feed intake as it did with beef cows, then it may prove to be a very effective energy supplement for increasing milk production. The objective was to evaluate catfish oil as a dietary ingredient for lactating Holstein cows during the summer season. Materials and Methods Cows and Diets Twelve multiparous, lactating Holstein cows (six ruminally fistulated) (mean of 195 27 DIM) were assigned to three dietary treatments arranged in a 3 X 3 Latin square design replicated four times. One square was composed of higher producing, nonfistulated cows, one square was composed of lower producing, nonfistulated cows, one square was composed of higher producing, fistulated cows, and one square was composed of lower producing, fistulated cows. The three dietary treatments were 0, 1.5 and 3.0% catfish oil (DM basis, Protein Products, Inc., Gainesville, GA). The fatty acid profile of the catfish oil was similar to that of tallow, containing mostly oleic and palmitic acids (Table 3-1). Linoleic acid concentration however, was greater at 14% than is typically reported for tallow. Catfish oil was suspended in liquid sugarcane molasses (20% as-is basis, United States Sugar Corp., Clewiston, FL) and stored in a 6000 L plastic tank on farm. A second tank contained molasses without catfish oil. The respective molasses blends were mixed with concentrate ingredients in 1-ton batches and stored on a concrete apron under cover. The concentrates were then mixed with corn silage and alfalfa hay at the time of feeding in a weighing and mixing unit (American

PAGE 60

48 Calan, Inc., Northwood, NH) and offered twice daily at 0930 and 1400 h for ad libitum consumption allowing 10% orts. Table 3-1. Fatty acid profile of catfish oil. Fatty acid % of total fatty acids C 12:0 0.10 C 14:0 1.76 C 14:1 0.13 C 16:0 18.67 C 16:1 4.93 C 18:0 5.03 C 18:1 47.04 C 18:2 14.03 C 18:3 1.16 C 20:4 0.29 C 20:5 1.13 C 22:6 3.15 Other 2.58 The experiment was conducted at the University of Florida from August to November and consisted of three 27-d periods. The first 14 d of each period was used to adapt cows to a new diet and the last 13 d used for data collection. Cows were housed in a free-stall, open-sided barn fitted with Calan gates (American Calan Inc., Northwood, NH) to allow measurement of individual feed intake. Fans and misters were operated continuously for cooling purposes. Temperature and humidity were recorded outside and inside the barn every 15 min throughout the experiment (Onset Computer Corporation, Bourne, MA). Collection of Samples and Analysis Weights of feed offered and orts were recorded daily for each cow. Representative samples of concentrate mixes, corn silage, and alfalfa hay were collected weekly and composited for each experimental period. Corn silage and alfalfa hay samples were dried at 55C in a forced-air oven and ground to pass the 1-mm screen of a Wiley mill (A.H.

PAGE 61

49 Thomas, Philadelphia, PA) prior to compositing. Feedstuff samples were analyzed for DM (105C for 8 h), OM (512C for 8 h), NDF (Goering and Van Soest, 1970) using heat-stable -amylase, ADF (AOAC, 1990), 80% ethanol soluble carbohydrate (ESC) (Hall et al., 1999), starch (Hall et al., 1999), Kjedahl N (AOAC, 1990) using a boric acid modification during distillation, and ether extract (EE) (AOAC, 1990). CP was calculated by multiplying Kjedahl N x 6.25. In addition, mineral composition was determined by Dairy One (Ithaca, NY). Cows were milked daily at 0500, 1300 and 2100 h and milk weights recorded. Milk samples were collected for two consecutive milkings on d 16, 17, 23 and 24 of each period for determination of fat, protein and SCC. Somatic cell scores were generated as described by Norman et al. (2000) for statistical analysis of SCC. Samples were analyzed by Southeast Dairy Labs (McDonough, GA) by infrared technologies (Bentley 2000, Bentley Instruments, Chaska, MN). Two consecutive milk samples were collected on d 23 of each period for fatty acid analysis. These samples were stored at -20C. Milk fat was extracted by the method of Chilliard et al. (1991). The extracted oil was placed in 15 ml Pyrex, leak-proof, Teflon-lined screw cap tubes, flushed with N, and sent to Clemson University (Clemson, SC) on dry ice for analysis by gas chromatography (Jenkins, 2000). Due to extended exposure of some samples to room temperature, only 24 out of 33 samples were analyzed for fatty acids. Body weight was monitored by weighing the cows on two consecutive days at the beginning and the end of each period before the a.m. milking. Rectal temperatures were measured twice daily at 0430 and 1630 h on d 16, 18, 20, 22, 24 and 26 of each period.

PAGE 62

50 Blood samples (~10 ml) were collected from the coccygeal vessels into Becton Dickinson vacutainers (Becton Dickinson, Franklin Lakes, NJ) containing sodium heparin on d 26 and 27 of each period. Blood was stored on ice for transport and centrifuged at 3000 rpm (1916 x g) to separate plasma. Plasma was stored at C until analyzed. A Technicon Autoanalyzer (Technicon Instruments Corp., Chauncey, NY) was used to measure plasma glucose (a modification of Gouchman and Schmitz (1972) as described in Bran and Luebbe Industrial Method # 339-19) and blood urea nitrogen (BUN) (a modification of Marsh et al. (1965) as described in Bran and Luebbe Industrial Method # 339-01). Plasma insulin was analyzed using a double antibody radioimmunoassay procedure as described by Soeldner and Sloane (1965) and modified by Malven et al. (1987). Bound radioactivity in tubes was measured using a Packard auto gamma counter (model B-5005). The results were calculated using the log-logit curve fit. Sensitivity of the assay was 0.2 ng/ml and the intra-assay coefficient of variation was 11.8%. At 1630 h on d 23 and 24 of each period spot samples of urine were collected and measured for pH (Horiba twin pH meter B-213, Spectrum Technologies, Inc, Plainfield, IL). Eighty g of feces were collected, diluted in 80 ml of distilled water immediately after collection, and measured for pH (pH meter, model 15; Fisher Scientific, Pittsburg, PA). Urine samples were frozen at -20C and kept for analysis. In order to estimate microbial protein synthesis, creatinine and allantoin analysis were performed as described by Vagnoni et al. (1997).

PAGE 63

51 Apparent Digestibility Gelatin capsules containing 10 g of Cr 2 O 3 were administered orally via a balling gun twice daily at 0430 and 1630 h on d 15 to 24 of each period. Fecal grab samples were collected before the administration of the capsules on d 20 to 24 of each period. Fecal samples from daily collections were dried at 55C in a force-air oven and ground to pass the 1-mm screen of a Wiley mill (A.H. Thomas, Philadelphia, PA). Samples of dried feces were composited across sampling times to obtained one fecal sample per cow per period. Feces were analyzed for Cr by atomic spectrophotometry (Williams et al., 1962), DM (105C for 8 h), OM (512C for 8 h), NDF (Goering and Van Soest, 1970) using heat-stable -amylase, ADF (AOAC, 1990), Kjedahl N (AOAC, 1990) using a boric acid modification during distillation, and EE was determined by Dairy One (Ithaca, NY). Apparent digestibility of DM, CP, ADF, NDF and EE were calculated by the marker ratio technique (Schneider and Flatt, 1975). Rate and Extent of Digestion Rate, extent, and lag of DM and NDF digestibility of corn silage were measured on d 25, 26, and 27 of each period by the dacron bag technique (Nocek, 1988). A single sample of corn silage was collected at the beginning of the trial, dried at 55C for 48 h, and ground to pass a 2-mm screen (Wiley mill, A.H. Thomas, Philadelphia, PA). Approximately 5.5 g (as-is) was weighed into preweighed polyester bags (10 x 20 cm) with an average pore size of 53 10 m (Bar Diamond, Inc., Parma, ID). Two single bags were inserted into a nylon bag attached to Nalgene bottles filled with sand and incubated in the rumen via canula at intervals of 0, 4, 8, 12, 18, 24, 36, 48, and 72 h starting on d 25 of each period. All bags were removed simultaneously. After removal,

PAGE 64

52 bags were placed in ice water, then washed under running tap water by hand. Finally bags were washed without soap in a washing machine on delicate/cold cycle to remove rumen fluid. Bags were oven-dried for 48 h at 55 C, then weighed to determine DM residue. The undigested residue was analyzed for NDF (Goering and Van Soest, 1970) using heat-stable -amylase. The equation for the determination of lag time and rate of DM and NDF digestion was the same as used in the study by Mertens and Ely (1982): R= D o e -K(t-L) + U when t > L and R= D o + U when 0 < t < L where R = DM or NDF residue at time t after incubation, D o = slowly digestible fraction at t L and D o = R U, K = digestion rate constant, L = discrete lag time, and U = indigestible fraction at 72 h of in situ fermentation. Digestion rate constants and discrete lag times were calculated with the nonlinear models procedure of SAS using Marqardts method (1996). Sampling and Analysis of Ruminal Fluid Ruminal fluid was collected hourly for 8 h starting at feeding on d 15 of each period using the ruminally fistulated cows. The pH was measured immediately upon collection (pH meter, model 15; Fisher Scientific, Pittsburg, PA). A subsample of about 30 ml was acidified with 50% sulfuric acid to a pH between 2 and 3 and centrifuged at 5400 x g for 20 min. The supernatant was collected and frozen immediately at -20C until further analysis for VFA on a 4% carbomax 80/120 BDA (Supelco Inc., Bellefonte, PA) column in a gas chromatograph (Autosystem XL, Perkin Elmer Inc., Norwalk CT).

PAGE 65

53 Prior to injection unto column, samples were centrifuged at 5000 x g for 30 min and filtered with a high affinity protein syringe-driven filter unit (Millex SLAA025LS, Fisher Scientific, Pittsburg, PA). The gas chromatograph was set to a flow rate of 30 ml/min of N, an injection port temperature of 200C, oven at 175C, and the flame ionizing detector at 450C. Protozoa numbers were determined as described by Dehority (1984). Ten ml of ruminal fluid that were collected every two hours for 8 h starting at feeding were mixed with 10 ml of 50% formaline and stored at room temperature until further analysis. Two drops of brilliant green dye were added to 1 mm aliquots of preserved ruminal fluid and allowed to stand overnight. After staining, 9 ml of 30% glycerol were added and 1ml of the diluted sample was pippeted into a Sedgewick-Rafter counting chamber (1-cm 3 volume). Protozoa were counted at a magnification of 100X. The goal was to have approximately 100 to 150 protozoa per 50 grids. Further dilutions were made with 30% glycerol if needed. Statistical Analysis Measurements of feed intake, milk production and composition, in situ lag, rate, and extent of digestion, apparent digestibility, pH of urine and feces, rectal temperatures, plasma glucose, plasma urea nitrogen, and microbial protein synthesis were analyzed by the general linear procedure (GLM) of SAS (1996). The model was Yijkl = + i + ij + k + l + () il +() ik + ijkl Yijkl = response variable in square i in period k in treatment l for cow j, = overall mean,

PAGE 66

54 i = effect of square i, ij = effect of cow j within square i, = effect of period k, = effect of treatment l, () il = effect of interaction of square i with treatment l, () ik = effect of interaction of square i with period k, and ijkl = residual effect of i, j, k, and l. Results are reported as least squares means. Significance was determined at P < 0.05 and a tendency toward significance at P < 0.12. The fatty acid profile of milk samples were analyzed as an incomplete Latin square design due to missing values. The model was the same as above except that square, square by treatment interaction, and square by period interaction were deleted. Repeated measures of ruminal pH, protozoa numbers, and VFA data were analyzed by the mixed procedure of SAS (1996). Covariance structures were tested to determine the best fit for each dependent variable. Single degree of freedom contrasts for linear and quadratic effects of treatment were tested. Two squares were designed as containing higher-producing cows and two squares were designed as containing lower-producing cows. The error term for square was cow within square. A reduced model was used pooling the square by period interaction with the error term if the square by period interaction was P > 0.25. Secondly, if the treatment by square interaction was P > 0.25, it was pooled with the error term, as well (Bancroft, 1968).

PAGE 67

55 Results and Discussion Diet Composition. As the proportion of CFO increased in the diet, the proportion of whole cottonseed decreased whereas that of soybean meal increased (Table 3-2). Diets contained similar concentrations of CP, starch, sugar, and minerals but concentration of dietary fiber decreased whereas that of EE increased with increasing concentration of CFO. Intake Response and Apparent Digestibility. Dry matter intake (kg/d and as a % of BW) increased linearly with increasing intake of CFO (Table 3-3). DePeters et al. (1987) also reported an increase in DMI when cows were fed diets of 3.5 and 7% yellow grease compared to those fed diets without yellow grease. Others have reported increased DMI as more saturated fats replaced unsaturated fats. As partially hydrogenated tallow replaced tallow, DMI increased from 23.1 to 24.7 kg/d (Pantoja et al., 1996). In agreement was the work of Pantoja et al. (1994) in which DMI increased as partially hydrogenated tallow replaced tallow which in turn replaced a tallow-canola oil mixture (20.8, 18.8, and 17.8 kg/d). The fatty acid profile of CFO contains less polyunsaturated fatty acids than whole cottonseeds (WCS). The fatty acid profile of WCS is 0.8% C14:0, 22.7% C16:0, 0.8% C16:1, 2.3% C18:0, 17.0% C18:1, 51.5% C18:2, and 0.2% C18:3 (Coppock and Wilks, 1991). When marine fish oils were a source of supplemental fat, DMI was depressed when the fish oil constituted 1.6% of dietary DM (Jones et al., 1998; Donovan et al., 2000; Cant et al., 1997; Whitlock et al., 2002; Doreau and Chilliard, 1997; Chilliard and Doreau, 1997; Keady et al., 2000; AbuGhazaleh et al., 2002; Lacasse et al., 2002) but was unchanged when fed at 1% of dietary DM (Donovan et al., 2000; Keady et al., 2000). Most studies have reported no effect on DMI by feeding yellow grease ((Martinez et al., 1991; Cant et

PAGE 68

56 al., 1991; Nianogo et al., 1991; Avila et al., 2000; Oldick et al., 1997) or tallow (Shauff et al., 1992; Smith et al., 1993; Eastridge and Firkins, 1991; Jenkins et al., 1998, Adams et al., 1995; Drackley and Elliot, 1993; Wu et al., 1993, Grummer et al., 1993; Markus et al., 1996; Weigel et al., 1997; Bateman et al., 1996) but others have reported a depression in DMI when tallow was fed at 2% of dietary DM (Onetti et al., 2001, 2002; Ruppert et al., 2003). The mechanisms by which supplemental fat sometimes depresses feed intake are not clear but could involve effects of fat on ruminal fermentation and gut motility, acceptability of diets containing added fat, release of gut hormones, and oxidation of fat in the liver (Allen, 2000). Accompanying the increase in DMI, apparent digestibility of DM increased linearly as intake of CFO increased (Table 3-3). Similar to this study, apparent digestibility of DM increased when cows were fed yellow grease (Jenkins and Jenny, 1989; Nianogo et al., 1991) or marine fish oil (Doreau and Chilliard, 1997; Keady et al., 2000). Part of this increase in DM digestibility in the present study was due to an increased digestibility of the EE fraction of the diet; that is, the EE in CFO was more digestible than that in whole cottonseeds and the other ingredients. The nonnutritive fraction of EE is known to be of lower digestibility than the fatty acid fraction of EE. Others have reported a greater apparent EE digestibility when cows were fed marine fish oil (Doreau and Chilliard, 1997), yellow grease (DePeters et al., 1987), or tallow (Ruppert et al., 2003; Smith et al., 1993). The apparent digestibility of CP also was increased linearly as intake of CFO increased (Table 3-3). Soybean meal increased in the diet along with increasing concentration of CFO. Therefore this increase in extent of CP digestion may have

PAGE 69

57 occurred simply because the protein in soybean meal was more digestible than that in whole cottonseed. (NRC, 2001). Alternatively replacing whole cottonseed oil with CFO may have relieved an inhibitory effect of cottonseed oil on ruminal microbes thus improving ruminal digestion of dietary CP. However others have reported an improvement in apparent CP digestibility when lactating dairy cows were fed yellow grease (Nianogo et al., 1991) or tallow (Lewis et al., 1999) and the fat sources replaced grains. Apparent digestibilities of NDF and ADF were increased linearly as intake of CFO increased (Table 3-3). Likewise Doreau and Chilliard (1997) reported an increase in NDF digestibility when marine fish oil was supplemented at 370 g/d. These findings are in contrast to other reports of supplemental fat depressing fiber digestibility (Cant et al., 1991; Nianogo et al., 1991; Oldick et al., 1997; Smith et al., 1993). It has been suggested often that the negative effect of dietary lipids on intake is mainly due to a depressive effect on ruminal digestion or to a low palatability of fat supplements. It was not the case in this study in which CFO enhanced both DMI and digestibility. The extent that fat may interfere with digestion depends on the amount fed and the source. Increasing esterification or saturation of fats generally lessens its negative effects on ruminal fermentation (Palmquist and Jenkins, 1980). Feeding CFO had a similar effect on digestibility by higherand lower-producing cows. Cows were gaining 0.9 kg/d (Table 3-3). No difference was detected in BW gain when cows were fed CFO, however cows fed CFO had numerically greater BW gain than cows fed the control diet. DePeters et al. (1987) reported greater BW gain by cows in late compared to early lactation when fed yellow grease.

PAGE 70

58 Morning rectal temperatures increased linearly as cows were fed increasing amounts of CFO whereas afternoon rectal temperatures tended to increase quadratically (Table 3-3). These increases were most likely due to increased DMI of cows fed CFO. In situ Dry Matter and Neutral Detergent Fiber Digestion. In situ lag, rate and extent of digestion of corn silage DM was unchanged by feeding CFO (Table 3-4). Greater milk producers had 3 h less lag time for DM digestion than lower producers. In situ lag time of NDF digestion was unchanged by CFO, but the rate of NDF digestion increased linearly with increasing amounts of CFO in the diet (0.023, 0.024, and 0.029 h -1 ). However the extent of NDF digestion at 72 h was similar across diets (average 63.4%). Increased rate of NDF digestion likely contributed to the increase in apparent total tract digestion of NDF observed in cows fed CFO (Table 3-3). Yang (2002) reported that NDF digestibilities were increased by 15% with addition of branched-chain VFA to the media. However the molar proportion of branched-chain VFA in the present study were not increased by feeding CFO. Unsaturated fatty acids can cause an alteration in the rumen ecosystem due to the suppression of methanogenic (and to a lesser extent cellulolytic) bacteria and protozoa (Van Soest, 1994). A decrease in methane production results in an alteration of the rumen fermentation leading to an increase in propionate production to maintain the rumen fermentation balance. The possible depression of methane producers in the rumen and no change in protozoa numbers by CFO inclusion in this study may have created a space in the microbial mass that cellulolytic bacteria occupied thus increasing fiber digestion.

PAGE 71

59 Milk Production and Composition. Milk production (Table 3-5) was unchanged by CFO in the diet. This is surprising since cows fed CFO consumed increasing amounts of digestible DM (Table 3-3). Donovan et al. (2000) reported that milk yield increased for cows fed 1% marine fish oil diets, but milk yield decreased when fish oil was fed at 3% of dietary DM. Keady et al. (2000) also reported an increase in milk yield when marine fish oil was fed at 0.9, 1.9 and 3.1% of dietary DM using diets high in grass silage. However others reported a reduction in milk production when feeding diets of 3.7% fish oil (Lacasse et al., 2002) or 2% fish oil (Whitlock et al., 2002). Milk fat concentration was unchanged by CFO, averaging 3.55% (Table 3-5). The milk fat response to ruminally available supplemental fat may differ depending on the source of forage. Smith et al. (1993) reported that milk fat percentage tended to be depressed when tallow was added to diets containing only corn silage (3.33 vs. 3.15%) but tended to be increased when tallow was added to diets containing both corn silage and alfalfa hay (3.27 vs. 3.58%) (tallow by corn silage vs. alfalfa hay interaction, P < 0.08). Ruppert et al. (2002) reported that milk fat percentage tended (P < 0.06) to decrease linearly as dietary tallow supplementation to corn silage-based diets increased (3.18, 2.89, and 2.70% for 0, 2, and 4% tallow diets, respectively) whereas it was unchanged when supplemented to alfalfa silage-based diets (3.39, 3.44, and 3.41% for 0, 2, and 4% tallow diets, respectively) (forage source by tallow interaction). This may be attributed to the higher content of non-FA lipid in EE from alfalfa silage compared with corn silage. In studies reporting milk fat depression due to fat supplementation (Onetti et al., 2002; Martinez et al., 1991), the depression was probably by inhibition on acetyl-CoA carboxylase by increased concentrations of long chain acyl CoA in the mammary gland

PAGE 72

60 (Palmquist and Jenkins, 1980). In this study, production of milk fat and 4% FCM were not affected by CFO supplementation. Milk protein percentage, milk protein yield, and somatic cell counts were unchanged by the inclusion of CFO in the diets. In agreement are others who have reported no effect of supplemental tallow or yellow grease on milk protein percentage (Avila et al., 2000; Martinez et al., 1991; Onetti et al., 2002). Fatty Acid Composition of Milk Fat. Shortand medium-chain fatty acids, C4:0 to C12:0 in milk fat, were not affected by inclusion of CFO in the diet (Table 3-6). The supply of long chain fatty acids to the mammary gland was not changed appreciably by replacing whole cottonseed with CFO. Therefore it is not unexpected that concentrations of C4 to C12 fatty acids were similar across diets. Concentration of C14:0 tended (P = 0.08) to increase linearly in milk fat of cows fed increasing amounts of CFO. The concentrations of fatty acids C14:1 and C16:1 increased linearly in milk fat of cows fed increasing amounts of CFO. Concentration of C18:0 in milk fat decreased linearly with inclusion of CFO in the diet. The concentration of C18:2 tended (P = 0.07) to decrease by increasing amounts of CFO in the milk fat, whereas increasing concentration of C20:5 due to CFO supplementation came close to significance (P = 0.11). These effects were likely due to the differences in fatty acid profiles between CFO and WCS. Whole cottonseeds oil contains greater concentrations of 18-carbon fatty acids. Fiber digestibility was not depressed in this study, thus having no effect on the availability of acetate for de novo synthesis of fatty acids in the mammary gland (Eastridge and Firkins, 1991). Concentrations of cis-9, trans 11 C18:2 and trans-10, cis-12 C18:2 increased numerically with increasing intake of CFO but large standard errors prevented these response from being significant. Others (AbuGhazaleh et

PAGE 73

61 al., 2002; Whitlock et al., 2002) have reported that the feeding of marine fish oil increased the conjugated linoleic acid concentration of milk fat. A lack of response in the current study was likely due to a lower concentration of EPA and DHA in CFO compared to that in marine fish oil (Whitlock et al., 2002). Ruminal Fermentation. Diet by hour interactions were not observed for any of the ruminal measurements. Ruminal fluid pH decreased linearly when cows were fed diets of increasing concentration of CFO (6.41, 6.20, and 6.15 for 0, 1.5, 3.0% CFO, respectively; Table 3-7). This lower pH may have resulted from greater intake and digestibility of DM of diets with increasing concentration of CFO (Table 3-3). Lower producing cows experienced a sharp drop in ruminal pH when CFO was increased in the diet but higher producing cows had the highest ruminal pH when fed the 1.5% CFO diet (Figure 3-1; quadratic effect of diet by square interaction). Grummer et al. (1993) observed a linear reduction in ruminal pH with increasing concentrations of tallow in the diet (0, 1, 2, and 3%) Authors indicated that this reduction reflected a stimulation rather than an inhibition of fermentation as DMI was unchanged by tallow supplementation. Total VFA concentrations in ruminal fluid were similar across diets. This is somewhat surprising since ruminal fluid pH decreased linearly as intake of CFO increased. The VFA are absorbed from the rumen at a faster rate with decreasing pH. Therefore increased production of VFA accompanied by increased absorption of VFA may have resulted in no net change in VFA concentration of cows fed CFO compared to controls. In high producing cows molar proportion of acetate in ruminal fluid decreased linearly with increasing concentrations of CFO in the diet (65.1, 64.0, and 63.0 molar % for cows fed 0, 1.5, and 3.0% CFO diets, respectively) whereas that of lower producing

PAGE 74

62 cows was unchanged (Figure 3-2; linear effect of diet by square interaction). Molar proportion of propionate increased linearly by adding CFO in the diet (19.4, 20.0, and 20.4 molar% for 0, 1.5, 3.0% CFO). As a result, the acetate to propionate ratio in ruminal fluid decreased linearly as more CFO was fed to cows. Doreau and Chilliard (1997) reported a decrease in molar proportion of acetate and an increase in propionate in ruminal fluid of cows fed diets supplemented with 370 g/d menhaden fish oil. Similarly results were obtained by Onetti et al. (2001), Elliot et al. (1993), Lewis et al. (1999), and Shauff et al. (1992) when tallow was the source of fat. Molar proportions of butyrate tended to increase with CFO (12.2, 12.4, 12.5 molar %, for 0, 1.5, 3.0% CFO, respectively). This response was more evident in high producing cows (Figure 3-3; linear effect of diet by square interaction). Molar proportions of isobutyrate, 2-methylbutyrate, valerate, and isovalerate decreased in ruminal fluid of cows fed 1.5% CFO but then increased when cows were fed diets of 3% CFO (quadratic effect of diet). The response pattern of the branch chained fatty acids due to feeding CFO of lower producing cows showed a greater depression at the 1.5% CFO diet that did higher producing cows (Figures 3-4, 3-5, and 3-6; diet by square interactions). As reported by Doreau and Chilliard (1996), the modification of the VFA profile suggests a change in the ruminal microbial ecosystem. The changes in the present study were not negative since an improvement in rate of NDF digestion and total tract apparent digestibility was improved. Onetti et al. (2001) reported a decrease in protozoa number per milliliter of rumen fluid as tallow or choice white grease increased in the diet from 0 to 4% of dietary DM. Their study reported no difference in protozoa numbers between sources of fat. In the current study, protozoa numbers in ruminal fluid were decreased in cows fed 1.5% CFO

PAGE 75

63 diets in lower producing cows whereas, in higher producing cows, the protozoa numbers were greater when cows were fed the 1.5% CFO diet (Figure 3-7; quadratic effect of diet by square interaction). Microbial protein yield (g/d) increased in cows fed diets of 1.5% CFO but returned to that of controls when cows were fed diets of 3.0% CFO (quadratic effect). This may have contributed to the improvement in diet digestibility (Table 3-3) and rate of NDF digestion (Table 3-4). Urine pH from higher producing cows increased linearly whereas that of lower producing cows decreased linearly with increasing dietary concentration of CFO (Figure 3-8; linear effect of diet by square interaction). Feeding CFO at 1.5% of dietary DM resulted in elevated fecal pH from lower milk producers but lower fecal pH from high milk producers (Figure 3-9; quadratic effect of diet by square interaction). Blood Metabolites. Plasma urea, glucose, or insulin were not affected by CFO supplementation (Table 3-8). Other studies have reported no change in plasma glucose concentration when fat was added to the diet (Ruppert et al., 2003; Shauff et al., 1992; Wu et al., 1993; Ahnadi et al., 2002). Bateman et al. (1996) observed an increase in plasma glucose with addition of tallow at 0.45 kg/d. Palmquist and Jenkins (1980) noted in their review that high fat diets can result in an inability of insulin to stimulate glucose utilization by tissues, thus causing an increase in plasma glucose concentration. A decrease in plasma glucose concentration with increased concentration of yellow grease in the diets was reported by Avila et al. (2000) and Cant et al. (1993). Similar to this study, Smith et al. (1993), Ruppert et al. (2003), and Shauff et al. (1992) reported no effect of fat supplementation on blood urea nitrogen concentration.

PAGE 76

64 Summary Catfish oil mixed with liquid molasses and fed to lactating Holstein cows at 1.5 and 3% of dietary dry matter stimulated dry matter intake and digestibility. Fermentation in the rumen was not affected negatively by feeding CFO based upon improved in situ digestion rate of NDF, lack of appreciable change in VFA, and improved synthesis of microbial protein. Although the production and composition of milk was unchanged by feeding CFO in this study, the improvement in feed intake and digestibility hold promise that milk production could be improved in future work.

PAGE 77

65 Table 3-2. Ingredient and chemical composition of experimental diets containing catfish oil (CFO) fed to lactating Holstein cows in summer. DIET Ingredient 0% CFO 1.5% CFO 3.0% CFO Corn silage, % of DM 29.9 29.9 29.9 Alfalfa hay, % of DM 11.5 11.5 11.5 Cottonseed hulls, % of DM 4.7 4.7 4.7 Corn meal, % of DM 17.2 17.2 17.0 Soybean meal, % of DM 11.5 13.0 14.4 Citrus pulp, % of DM 5.6 5.6 5.6 Whole cottonseed, % of DM 5.2 2.6 0 Prolak, % of DM 1 1.5 1.5 1.5 Liquid molasses, % of DM 2 8.1 4.0 0 Liquid molasses + CFO, % of DM 3 0 5.3 10.5 Mineral mix, % of DM 4 4.4 4.4 4.4 Biophos, % of DM 5 0.3 0.3 0.5 Chemical CP, % of DM 18.3 18.3 18.5 NDF, % of DM 30.3 30.9 28.5 ADF, % of DM 18.9 18.7 17.1 Ether extract, % of DM 4.75 5.33 5.59 Starch, % of DM 23.1 23.3 24.1 Sugars, % of DM 9.3 8.7 9.3 Ca, % of DM 1.31 1.35 1.34 P, % of DM 0.47 0.47 0.49 Mg, % of DM 0.38 0.40 0.44 K, % of DM 1.79 1.77 2.10 Na, % of DM 0.51 0.49 0.50 S, % of DM 0.34 0.34 0.32 Cu, ppm of DM 32 32 29 Fe, ppm of DM 244 250 260 Mn, ppm of DM 104 110 108 Zn, ppm of DM 99 122 119 1 H. J. Baker & Bro., Inc., Stanford, CT. 2 United States Sugar Corp., Clewiston, FL. 3 CFO supplied by Protein Products, Inc., Gainesville, GA to United States Sugar Corp. (Clewiston, FL) for mixing at 20.0% (as-is basis). 4 Mineral and vitamin mix contained 26.4% CP, 1.74% fat, 10.15% Ca, 0.90% P, 3.1% Mg, 8.6% Na, 5.1% K, 1.5% S, 4.1% Cl, 2231 mg/kg of Mn, 1698 mg/kg of Zn, 339 mg/kg Fe, 512 mg/kg of Cu, 31 mg/kg of Co, 26 mg/kg of I, 7.9 mg/kg of Se, 67,021 IU/kg of vitamin A, 19,845 IU/kg of vitamin D, and 357 IU/kg of vitamin E (DM basis). 5 IMC-Agrico, Bannockburn, IL.

PAGE 78

Table 3-3. Dry matter intake (DMI), apparent digestibility coeficients of DM, CP, NDF, ADF and ether extract (EE), body weight change, and rectal temperatures (RT) of lactating Holstein cows fed catfish oil (CFO) in summer. 66 Square Diet Square Diet x square interaction CFO in dietary DM Linear Quadratic HM vs. LM Linear x HM vs. LM Quadratic x HM vs. LM Measure 0% 1.5% 3.0% Higher milk producers (HM) Lower milk producers (LM) SE -------------------------------P value--------------------------------------DMI, kg/d 23.0 24.4 25.4 26.0 22.6 0.6 0.01 0.81 0.001 1 1 DMI, % of BW 3.2 3.4 3.5 3.7 3.1 0.08 0.03 0.94 0.001 0.21 0.92 Apparent digestibility, % DM 69.9 74.5 75.3 74.2 72.3 0.81 0.001 0.08 0.07 0.31 0.68 CP 72.2 75.8 76.2 75.4 74.1 0.96 0.01 0.19 0.27 0.91 0.70 NDF 51.9 59.0 58.5 57.7 55.2 1.72 0.02 0.10 0.23 0.65 0.94 ADF 41.5 50.4 49.0 50.0 43.9 2.05 0.02 0.06 0.02 0.56 0.84 EE 91.5 93.7 94.4 93.5 92.9 0.3 0.004 0.06 0.07 0.40 0.87 Body weight change, kg/27 days 25.3 35.0 31.0 31.0 30.0 6.3 0.55 0.42 0.89 0.35 0.34 RT at 0430 h, C 38.2 38.2 38.4 38.3 38.3 0.04 0.03 0.13 1.0 0.09 0.98 RT at 1630 h, C 38.7 38.8 38.7 38.8 38.7 0.04 0.99 0.08 0.09 1 1 1 P values were not generated due to use of reduced model.

PAGE 79

Table 3-4. In situ lag, rate, and extent of DM and NDF digestion of corn silage by lactating Holstein cows fed catfish oil (CFO) in summer. 67 Square Diet Square Diet x square interaction CFO in dietary DM Linear Quadratic HM vs. LM Linear x HM vs. LM Quadratic x HM vs. LM Measure 0% 1.5% 3.0% Higher milk producers (HM) Lower milk producers (LM) SE ----------------------------------P value--------------------------------------DM Lag, h 2.1 1.8 4.9 1.4 4.4 0.8 0.08 0.17 0.035 0.10 0.65 Rate, h -1 0.022 0.022 0.029 0.023 0.026 0.002 0.12 0.40 0.47 0.22 0.81 72 h extent, % 83.7 81.7 83.2 81.7 84.1 1.4 0.85 0.43 0.26 0.57 0.70 NDF Lag, h 9.7 8.8 10.8 8.4 11.0 1.5 0.82 0.73 0.49 0.96 0.54 Rate, h -1 0.023 0.024 0.029 0.024 0.026 0.001 0.04 0.24 0.28 0.11 0.86 72 h extent, % 65.5 60.4 64.3 60.4 66.3 3.2 0.83 0.38 0.23 0.55 0.68 Table 3-5. Milk production and composition of lactating Holstein cows fed catfish oil (CFO) in summer. Square Diet Square Diet x square interaction CFO in dietary DM Linear Quadratic HM vs. LM Linear x HM vs. LM Quadratic x HM vs. LM Measure 0% 1.5% 3.0% Higher milk producers (HM) Lower milk producers (LM) SE -----------------------------------P value-------------------------------------Milk, kg/d 29.0 29.0 29.5 34.5 23.8 0.5 0.52 0.72 0.001 0.81 0.61 Milk fat, % 3.57 3.60 3.48 3.48 3.62 0.14 0.70 0.71 0.40 0.84 0.46 Milk fat, kg/d 1.03 1.02 1.01 1.18 0.86 0.05 0.81 0.99 0.001 0.70 0.72 Milk protein, % 3.21 3.18 3.23 3.10 3.32 0.02 0.48 0.27 0.001 0.67 0.19 Milk protein, kg/d 0.91 0.91 0.94 1.06 0.78 0.02 0.39 0.54 0.001 0.69 0.34 4% FCM, kg/d 27.0 27.0 27.0 31.5 22.5 0.8 0.96 0.94 0.001 0.77 0.66 SCC x 1000/ml 154 95 109 176 130 0.5 0.51 0.49 0.14 0.80 0.81

PAGE 80

68 Table 3-6. Fatty acid composition of milk fat of lactating Holstein cows fed catfish oil (CFO) in summer. Diets CFO in dietary DM Linear Quadratic Measure 0% 1.5% 3.0% SE ------------P values---------% Fatty acids C4:0 3.51 3.52 3.36 0.11 0.32 0.59 C6:0 2.37 2.49 2.41 0.06 0.62 0.27 C8:0 1.28 1.38 1.36 0.05 0.28 0.45 C10:0 2.88 3.13 3.10 0.15 0.31 0.51 C11:0 0.03 0.05 0.04 0.01 0.37 0.47 C12:0 3.22 3.55 3.61 0.19 0.16 0.61 C14:0 10.32 11.21 11.38 0.39 0.08 0.51 C14:1 1.28 1.51 1.63 0.07 0.004 0.52 C15:0 0.82 0.94 0.93 0.05 0.13 0.31 C16:0 29.05 28.93 30.04 0.56 0.22 0.43 C16:1 1.43 1.59 1.84 0.08 0.004 0.68 C17:0 0.48 0.47 0.46 0.02 0.23 0.89 C18:0 10.31 9.10 7.89 0.62 0.02 0.99 C18:1 20.93 19.27 19.46 0.80 0.21 0.41 trans-C18:1 1.57 2.15 1.83 0.27 0.48 0.25 C18:2 3.32 3.05 3.07 0.09 0.07 0.27 C18:3 0.33 0.32 0.35 0.02 0.44 0.50 cis-9, trans-11 CLA 0.008 0.009 0.011 0.005 0.62 0.98 trans-9, cis11 CLA 0.05 0.05 0.05 0.004 0.71 0.81 trans-10, cis12 CLA 0.004 0.009 0.010 0.005 0.40 0.73 C20:0 0.18 0.19 0.18 0.01 0.94 0.75 C21:0 0.06 0.06 0.07 0.003 0.10 0.46 C22:0 0.19 0.19 0.18 0.01 0.20 0.51 C22:1 0.20 0.19 0.20 0.01 0.96 0.31 C20:5 0.02 0.02 0.03 0.005 0.11 0.38 C24:0 0.02 0.03 0.02 0.007 0.66 0.39 C22:6 0.02 0.04 0.03 0.03 0.84 0.70

PAGE 81

Table 3-7.Volatile fatty acid concentration, pH, microbial protein production, and protozoa numbers in ruminal fluid and pH of urine and feces of lactating Holstein cows fed catfish oil (CFO) in summer. 69 Square Diet Square Diet x square interaction CFO in dietary DM Linear Quadratic HM vs. LM Linear x HM vs. LM Quadratic x HM vs. LM Measure 0% 1.5% 3.0% Higher milk producers (HM) Lower milk producers (LM) SE -------------------------------P value------------------------------------Ruminal fluid pH 6.41 6.20 6.15 6.16 6.34 0.07 0.001 0.12 0.23 0.001 0.001 Acetate, molar % 64.5 64.2 63.4 64.0 64.0 0.77 0.02 0.58 0.99 0.02 0.51 Propionate, molar % 19.4 20.0 20.4 20.2 19.7 0.53 0.02 0.78 0.62 0.40 0.78 Butyrate, molar % 12.2 12.4 12.5 12.1 12.6 0.43 0.08 0.37 0.59 0.05 0.93 Isobutyrate, molar % 0.77 0.62 0.68 0.68 0.70 0.04 0.006 0.001 0.80 0.001 0.03 2-Methylbutyrate, molar% 1.30 1.08 1.17 1.06 1.31 0.08 0.04 0.003 0.20 0.02 0.41 Valerate, molar % 1.32 1.26 1.37 1.48 1.16 0.09 0.43 0.07 0.16 0.79 0.95 Isovalerate, molar % 0.51 0.38 0.44 0.41 0.47 0.04 0.01 0.001 0.48 0.02 0.01 Total VFA, mM 109.1 112.6 111.9 119.0 103.4 12.0 0.69 0.73 0.54 0.15 0.23 Acetate:Propionate 3.38 3.22 3.18 3.23 3.30 0.13 0.01 0.35 0.81 0.06 0.89 Microbial protein, g/d 298 342 285 303 313 11 0.42 0.016 0.47 0.55 0.77 Protozoa, x10 5 /ml 7.6 7.1 7.7 7.0 7.9 0.6 0.86 0.23 0.39 0.29 0.009 Urine pH 8.05 8.05 8.06 8.06 8.04 0.02 0.92 0.80 0.30 0.03 0.67 Fecal pH 6.69 6.71 6.68 6.66 6.72 0.02 0.83 0.38 0.02 0.69 0.03 Table 3-8. Concentrations of plasma urea, glucose and insulin of lactating Holstein cows fed catfish oil (CFO) in summer. Square Diet Square Diet x square interaction CFO in dietary DM Linear Quadratic HM vs. LM Linear x HM vs. LM Quadratic x HM vs. LM Measure 0% 1.5% 3.0% Higher milk producers (HM) Lower milk producers (LM) SE -----------------------------------P value---------------------------------------Plasma urea, mg/dl 11.6 11.0 12.0 11.5 11.5 0.4 0.61 0.20 0.89 0.86 0.25 Plasma glucose, mg/dl 57.8 55.1 56.0 55.6 57.0 1.1 0.30 0.24 0.33 0.96 0.42 Plasma insulin, ng/ml 0.55 0.53 0.57 0.51 0.58 0.04 0.74 0.56 0.17 0.55 0.14

PAGE 82

70 5.45.65.86.06.26.46.66.87.0Low ProducersHigh ProducersRuminal fluid pH 0 % CFO 1.5 % CFO 3 % CFO Figure 3-1. Ruminal fluid pH for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Quadratic effect of diet by square interaction, P = 0.001. 59.060.061.062.063.064.065.066.067.0Low ProducersHigh ProducersAcetate, molar % 0 % CFO 1.5 % CFO 3 % CFO Figure 3-2. Molar proportion of acetate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Linear effect of diet by square interaction, P = 0.02.

PAGE 83

71 10.010.511.011.512.012.513.013.5Low ProducersHigh ProducersButyrate, molar % 0 % CFO 1.5 % CFO 3 % CFO Figure 3-3. Molar proportion of butyrate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Linear effect of diet by square interaction, P = 0.05. 0.00.10.20.30.40.50.60.70.80.91.0Low ProducersHigh ProducersIsobutyrate, molar % 0 % CFO 1.5 % CFO 3 % CFO Figure 3-4. Molar proportion of isobutyrate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Quadratic effect of diet by square interaction, P = 0.03.

PAGE 84

72 0.00.20.40.60.81.01.21.41.61.8Low ProducersHigh Producers2-Methylbutyrate, molar % 0 % CFO 1.5 % CFO 3 % CFO Figure 3-5. Molar proportion of 2-methylbutyrate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Linear effect of diet by square interaction, P = 0.02. 0.00.10.20.30.40.50.60.7Low ProducersHigh ProducersIsovalerate, molar % 0 % CFO 1.5 % CFO 3 % CFO Figure 3-6. Molar proportion of isovalerate in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Quadratic effect of diet by square interaction, P = 0.01.

PAGE 85

73 024681012Low ProducersHigh ProducersProtozoa, x 10 5/ml 0 % CFO 1.5 % CFO 3 % CFO Figure 3-7. Protozoa numbers in ruminal fluid for low milk producers and high milk producers fed 0, 1.5, 3.0% catfish oil (CFO). Quadratic effect of diet by square interaction, P = 0.009. 7.857.97.9588.058.18.158.2Low ProducersHigh ProducersUrine pH 0 % CFO 1.5 % CFO 3 % CFO Figure 3-8. Urine pH for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Linear effect of diet by square interaction, P = 0.03.

PAGE 86

74 6.456.56.556.66.656.76.756.86.85Low ProducersHigh ProducersFecal pH 0 % CFO 1.5 % CFO 3 % CFO Figure 3-9. Fecal pH for low milk producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Quadratic effect of diet by square interaction, P = 0.03.

PAGE 87

APPENDIX TEMPERATURE AND RELATIVE HUMIDITY Table A-1. Average temperature (Temp), relative humidity (RH), and temperature humidity index (THI) in 6-h increments on collection days measured within the free stall barn at the Dairy Research Unit at Hague, Florida. 1 Period Date Time Frame, h Temp, C RH, % THI 2 1 9-4-01 0000 0559 23.15 92.85 73.5 1 9-4-01 0600 1159 24.58 89.00 75.6 1 9-4-01 1200 1759 30.43 65.65 81.8 1 9-4-01 1800 2359 25.43 84.46 76.5 1 9-5-01 0000 0559 23.12 92.51 73.4 1 9-5-01 0600 1159 24.30 89.03 75.1 1 9-5-01 1200 1759 31.61 59.71 82.5 1 9-5-01 1800 2359 24.55 90.39 75.7 1 9-6-01 0000 0559 23.15 95.20 73.7 1 9-6-01 0600 1159 24.42 92.68 75.7 1 9-6-01 1200 1759 28.90 74.23 80.8 1 9-6-01 1800 2359 23.97 91.52 74.8 1 9-7-01 0000 0559 22.54 94.66 72.6 1 9-7-01 0600 1159 23.86 91.66 74.6 1 9-7-01 1200 1759 30.43 61.44 81.1 1 9-7-01 1800 2359 24.93 87.54 76.0 1 9-8-01 0000 0559 22.22 95.35 72.0 1 9-8-01 0600 1159 23.44 94.33 74.1 1 9-8-01 1200 1759 29.39 68.96 80.7 1 9-8-01 1800 2359 26.43 80.34 77.7 1 9-9-01 0000 0559 23.39 93.58 74.0 1 9-9-01 0600 1159 24.32 89.97 75.2 1 9-9-01 1200 1759 29.07 70.03 80.4 1 9-9-01 1800 2359 26.02 86.67 77.8 1 9-10-01 0000 0559 23.51 93.88 74.2 1 9-10-01 0600 1159 24.35 90.66 75.3 1 9-10-01 1200 1759 28.29 76.30 80.1 1 9-10-01 1800 2359 26.12 84.85 77.7 1 9-11-01 0000 0559 23.24 94.14 73.8 1 9-11-01 0600 1159 25.10 89.04 76.5 1 9-11-01 1200 1759 28.63 73.36 80.2 1 9-11-01 1800 2359 24.38 90.27 75.4 1 9-12-01 0000 0559 22.80 93.43 72.9 75

PAGE 88

76 Table A-1. Continued Period Date Time Frame, h Temp, C RH, % THI 2 1 9-12-01 0600 1159 23.89 90.98 74.6 1 9-12-01 1200 1759 26.90 78.51 78.2 1 9-12-01 1800 2359 22.90 93.40 73.1 1 9-13-01 0000 0559 22.09 95.97 71.9 1 9-13-01 0600 1159 22.35 94.39 72.2 1 9-13-01 1200 1759 23.37 89.84 73.6 1 9-13-01 1800 2359 20.98 94.28 69.8 1 9-14-01 0000 0559 21.05 94.96 70.0 1 9-14-01 0600 1159 21.12 96.20 70.2 1 9-14-01 1200 1759 21.84 95.41 71.4 1 9-14-01 1800 2359 21.17 96.28 70.3 1 9-15-01 0000 0559 20.68 96.02 69.4 1 9-15-01 0600 1159 19.22 89.88 66.5 1 9-15-01 1200 1759 22.78 72.63 71.1 1 9-15-01 1800 2359 20.82 78.84 68.5 1 9-16-01 0000 0559 18.08 75.62 64.0 1 9-16-01 0600 1159 17.57 79.54 63.4 1 9-16-01 1200 1759 25.87 57.46 74.2 1 9-16-01 1800 2359 22.91 74.55 71.5 2 10-1-01 0000 0559 13.32 87.88 56.4 2 10-1-01 0600 1159 14.55 74.36 58.5 2 10-1-01 1200 1759 22.24 37.99 67.6 2 10-1-01 1800 2359 17.63 65.80 63.0 2 10-2-01 0000 0559 11.85 88.23 53.9 2 10-2-01 0600 1159 14.44 79.08 58.3 2 10-2-01 1200 1759 24.18 42.41 70.3 2 10-2-01 1800 2359 19.93 71.49 66.7 2 10-3-01 0000 0559 14.61 88.76 58.6 2 10-3-01 0600 1159 15.66 85.70 60.4 2 10-3-01 1200 1759 25.84 47.52 73.0 2 10-3-01 1800 2359 21.58 74.32 69.4 2 10-4-01 0000 0559 17.08 91.11 62.9 2 10-4-01 0600 1159 19.29 84.96 66.4 2 10-4-01 1200 1759 27.16 51.93 75.2 2 10-4-01 1800 2359 22.93 73.85 71.5 2 10-5-01 0000 0559 20.49 82.03 68.2 2 10-5-01 0600 1159 21.90 80.60 70.4 2 10-5-01 1200 1759 28.82 54.20 77.8 2 10-5-01 1800 2359 24.07 78.65 73.7 2 10-6-01 0000 0559 22.35 90.45 71.9 2 10-6-01 0600 1159 24.70 88.75 75.7 2 10-6-01 1200 1759 29.40 66.48 80.4 2 10-6-01 1800 2359 25.20 81.53 75.8 2 10-7-01 0000 0559 22.41 93.70 72.3

PAGE 89

77 Table A-1. Continued Period Date Time Frame,h Temp, C RH,% THI 2 2 10-7-01 0600 1159 20.60 89.85 68.9 2 10-7-01 1200 1759 21.38 78.28 69.4 2 10-7-01 1800 2359 19.01 80.72 65.7 2 10-8-01 0000 0559 16.73 83.29 62.1 2 10-8-01 0600 1159 18.41 79.95 64.7 2 10-8-01 1200 1759 24.25 67.93 72.9 2 10-8-01 1800 2359 20.44 82.25 68.1 2 10-9-01 0000 0559 18.15 92.82 64.8 2 0600 1159 19.41 85.09 66.6 2 10-9-01 1200 1759 25.08 58.38 73.1 2 10-9-01 1800 2359 21.65 73.33 69.5 2 10-10-01 0000 0559 18.07 89.95 64.5 2 10-10-01 0600 1159 19.10 86.65 66.1 2 10-10-01 1200 1759 24.56 73.04 73.9 2 10-10-01 1800 2359 22.64 79.22 71.5 2 10-11-01 0000 0559 20.21 90.75 68.2 2 10-11-01 0600 1159 21.43 86.54 70.0 2 10-11-01 1200 1759 26.91 59.06 75.8 2 10-11-01 1800 2359 22.42 78.83 71.1 2 10-12-01 0000 0559 19.73 91.78 67.5 2 10-12-01 0600 1159 21.45 86.02 70.0 2 10-12-01 1200 1759 27.03 64.48 76.6 2 10-12-01 1800 2359 23.60 82.33 73.3 2 10-13-01 0000 0559 21.33 89.96 70.1 2 10-13-01 0600 1159 22.44 87.02 71.8 2 10-13-01 1200 1759 27.83 63.49 77.7 2 10-13-01 1800 2359 24.53 80.86 74.7 3 10-28-01 0000 0559 7.11 60.39 48.0 3 10-28-01 0600 1159 7.52 63.99 48.3 3 10-28-01 1200 1759 16.50 46.82 61.0 3 10-28-01 1800 2359 12.50 69.07 55.4 3 10-29-01 0000 0559 9.28 69.78 50.5 3 10-29-01 0600 1159 10.82 68.47 52.9 3 10-29-01 1200 1759 19.95 59.64 66.1 3 10-29-01 1800 2359 15.39 76.38 59.8 3 10-30-01 0000 0559 10.53 78.98 52.1 3 10-30-01 0600 1159 11.85 75.95 54.3 3 10-30-01 1200 1759 22.85 50.81 69.4 3 10-30-01 1800 2359 18.01 74.26 63.9 3 10-31-01 0000 0559 13.48 91.35 56.7 3 10-31-01 0600 1159 15.44 91.31 60.0 3 10-31-01 1200 1759 23.79 66.45 72.1 3 10-31-01 1800 2359 21.00 79.09 68.8 3 11-1-01 0000 0559 18.83 90.66 65.9 10-9-01

PAGE 90

78 Table A-1. Continued Period Date Time Frame, h Temp, C RH, % THI 2 3 11-1-01 0600 1159 19.49 88.03 66.9 3 11-1-01 1200 1759 26.15 59.82 74.8 3 11-1-01 1800 2359 21.94 79.93 70.4 3 11-2-01 0000 0559 19.25 92.81 66.7 3 11-2-01 0600 1159 21.16 91.43 69.9 3 11-2-01 1200 1759 26.47 68.58 76.3 3 11-2-01 1800 2359 23.18 80.85 72.5 3 11-3-02 0000 0559 20.49 92.95 68.9 3 11-3-01 0600 1159 20.71 92.09 69.2 3 11-3-01 1200 1759 26.72 68.38 76.7 3 11-3-01 1800 2359 22.04 84.40 70.9 3 11-4-01 0000 0559 19.60 94.67 67.4 3 11-4-01 0600 1159 20.87 91.73 69.4 3 11-4-01 1200 1759 24.22 74.45 73.5 3 11-4-01 1800 2359 20.65 83.78 68.6 3 11-5-01 0000 0559 18.82 86.08 65.6 3 11-5-02 0600 1159 17.52 79.84 63.3 3 11-5-01 1200 1759 19.49 51.72 65.0 3 11-5-01 1800 2359 15.47 68.82 59.9 3 11-6-01 0000 0559 9.98 85.46 50.9 3 11-6-01 0600 1159 11.24 77.33 53.3 3 11-6-01 1200 1759 21.12 43.72 66.7 3 11-6-01 1800 2359 14.90 68.61 59.0 3 11-7-01 0000 0559 7.42 89.23 46.4 3 11-7-01 0600 1159 9.28 82.98 49.9 3 11-7-01 1200 1759 21.92 31.96 66.8 3 11-7-01 1800 2359 15.03 67.98 59.2 3 11-8-01 0000 0559 10.16 87.17 51.1 3 11-8-01 0600 1159 13.28 84.77 56.4 3 11-8-01 1200 1759 23.55 44.45 69.7 3 11-8-01 1800 2359 17.92 70.94 63.6 3 11-9-01 0000 0559 12.01 88.20 54.2 3 11-9-01 0600 1159 13.28 84.14 56.4 3 11-9-01 1200 1759 24.05 44.19 70.3 3 11-9-01 1800 2359 17.60 68.43 63.0 1 Measures taken every 15 minutes. 2 Temperature-Humidity Index: (0.81 x dry bulb temperature in C) + ((relative humidity/100) x (dry bulb temperature 14.4)) + 46.6.

PAGE 91

79 Table A-2. Average temperature (Temp),relative humidity (RH), and temperature humidity index (THI) on 6-h increments on collection days measured outside the free stall barn at the Dairy Research Unit at Hague, Florida. 1 Period Date Time Frame, h Temp, C RH, % THI 2 1 9-4-01 0000 0559 22.78 94.25 72.9 1 9-4-01 0600 1159 24.84 87.47 75.8 1 9-4-01 1200 1759 31.25 61.43 82.3 1 9-4-01 1800 2359 25.08 85.45 76.0 1 9-5-01 0000 0559 22.67 95.03 72.8 1 9-5-01 0600 1159 24.52 88.05 75.4 1 9-5-01 1200 1759 32.52 55.58 83.0 1 9-5-01 1800 2359 23.87 93.51 74.8 1 9-6-01 0000 0559 22.73 97.33 73.1 1 9-6-01 0600 1159 24.64 92.25 76.0 1 9-6-01 1200 1759 29.20 73.04 81.1 1 9-6-01 1800 2359 23.40 94.29 74.0 1 9-7-01 0000 0559 22.09 96.93 72.0 1 9-7-01 0600 1159 24.11 90.38 74.9 1 9-7-01 1200 1759 31.29 57.54 81.7 1 9-7-01 1800 2359 24.14 91.02 75.0 1 9-8-01 0000 0559 21.77 97.66 71.4 1 9-8-01 0600 1159 23.48 94.50 74.2 1 9-8-01 1200 1759 30.07 64.68 81.1 1 9-8-01 1800 2359 25.98 82.09 77.1 1 9-9-01 0000 0559 22.97 96.12 73.4 1 9-9-01 0600 1159 24.13 90.72 75.0 1 9-9-01 1200 1759 29.71 67.39 81.0 1 9-9-01 1800 2359 25.38 89.45 77.0 1 9-10-01 0000 0559 23.28 96.19 74.0 1 9-10-01 0600 1159 24.37 90.24 75.3 1 9-10-01 1200 1759 28.46 74.84 80.2 1 9-10-01 1800 2359 25.54 87.01 77.0 1 9-11-01 0000 0559 22.81 96.47 73.2 1 9-11-01 0600 1159 25.58 87.10 77.1 1 9-11-01 1200 1759 28.77 71.40 80.2 1 9-11-01 1800 2359 23.93 92.41 74.8 1 9-12-01 0000 0559 22.36 95.29 72.3 1 9-12-01 0600 1159 24.07 90.03 74.8 1 9-12-01 1200 1759 27.20 76.78 78.5 1 9-12-01 1800 2359 22.49 94.36 72.5 1 9-13-01 0000 0559 21.93 96.93 71.7 1 9-13-01 0600 1159 22.17 95.01 71.9 1 9-13-01 1200 1759 23.21 90.18 73.3 1 9-13-01 1800 2359 20.76 95.21 69.5 1 9-14-01 0000 0559 20.89 95.56 69.7 1 9-14-01 0600 1159 21.09 96.58 70.1

PAGE 92

80 Table A-2. Continued Period Date Time Frame, h Temp, C RH, % THI 2 1 9-14-01 1200 1759 21.90 95.22 71.5 1 9-14-01 1800 2359 21.19 96.05 70.3 1 9-15-01 0000 0559 20.63 96.29 69.3 1 9-15-01 0600 1159 19.23 89.75 66.5 1 9-15-01 1200 1759 23.34 70.04 71.8 1 9-15-01 1800 2359 20.51 80.50 68.1 1 9-16-01 0000 0559 17.62 77.28 63.4 1 9-16-01 0600 1159 17.73 79.30 63.6 1 9-16-01 1200 1759 27.67 51.91 75.9 1 9-16-01 1800 2359 22.50 76.41 71.0 2 10-1-01 0000 0559 11.49 94.30 53.2 2 10-1-01 0600 1159 14.47 74.36 58.4 2 10-1-01 1200 1759 23.15 33.74 68.3 2 10-1-01 1800 2359 16.66 67.20 61.6 2 10-2-01 0000 0559 10.06 93.44 50.7 2 10-2-01 0600 1159 14.98 77.29 59.2 2 10-2-01 1200 1759 25.84 35.65 71.6 2 10-2-01 1800 2359 19.72 71.42 66.4 2 10-3-01 0000 0559 13.52 92.19 56.7 2 10-3-01 0600 1159 16.33 84.49 61.4 2 10-3-01 1200 1759 27.32 40.51 74.0 2 10-3-01 1800 2359 21.53 74.76 69.4 2 10-4-01 0000 0559 16.55 95.47 62.1 2 10-4-01 0600 1159 19.84 83.65 67.2 2 10-4-01 1200 1759 28.37 45.53 75.9 2 10-4-01 1800 2359 23.07 72.60 71.6 2 10-5-01 0000 0559 20.24 83.80 67.9 2 10-5-01 0600 1159 21.86 80.18 70.3 2 10-5-01 1200 1759 29.52 48.08 77.8 2 10-5-01 1800 2359 23.99 78.91 73.6 2 10-6-01 0000 0559 22.09 91.87 71.6 2 10-6-01 0600 1159 24.59 89.06 75.6 2 10-6-01 1200 1759 29.50 64.94 80.3 2 10-6-01 1800 2359 24.75 82.53 75.2 2 10-7-01 0000 0559 21.96 95.88 71.6 2 10-7-01 0600 1159 20.22 91.33 68.3 2 10-7-01 1200 1759 21.36 77.36 69.3 2 10-7-01 1800 2359 18.65 82.04 65.2 2 10-8-01 0000 0559 16.21 85.88 61.3 2 10-8-01 0600 1159 18.59 79.32 65.0 2 10-8-01 1200 1759 24.77 64.85 73.4 2 10-8-01 1800 2359 19.95 84.75 67.5 2 10-9-01 0000 0559 17.55 96.45 63.9 2 10-9-01 0600 1159 19.70 83.92 67.0

PAGE 93

81 Table A-2. Continued Period Date Time Frame, h Temp, C RH, % THI 2 2 10-9-01 1200 1759 25.89 53.74 73.7 2 10-9-01 1800 2359 21.40 74.15 69.1 2 10-10-01 0000 0559 17.27 94.37 63.3 2 10-10-01 0600 1159 19.44 85.49 66.6 2 10-10-01 1200 1759 24.86 70.59 74.1 2 10-10-01 1800 2359 22.72 79.28 71.6 2 10-11-01 0000 0559 20.00 92.40 68.0 2 10-11-01 0600 1159 21.74 84.67 70.4 2 10-11-01 1200 1759 27.72 53.58 76.2 2 10-11-01 1800 2359 22.32 79.25 71.0 2 10-12-01 0000 0559 19.25 94.17 66.8 2 10-12-01 0600 1159 21.58 85.25 70.2 2 10-12-01 1200 1759 27.27 60.53 76.5 2 10-12-01 1800 2359 23.61 82.33 73.3 2 10-13-01 0000 0559 21.20 91.44 70.0 2 10-13-01 0600 1159 22.55 86.85 71.9 2 10-13-01 1200 1759 28.06 59.59 77.5 2 10-13-01 1800 2359 24.51 80.82 74.6 3 10-28-01 0000 0559 5.66 66.79 45.3 3 10-28-01 0600 1159 7.50 63.90 48.3 3 10-28-01 1200 1759 16.74 42.13 61.1 3 10-28-01 1800 2359 11.47 73.02 53.7 3 10-29-01 0000 0559 8.83 71.98 49.7 3 10-29-01 0600 1159 10.98 67.78 53.2 3 10-29-01 1200 1759 20.70 53.87 66.8 3 10-29-01 1800 2359 14.75 78.79 58.8 3 10-30-01 0000 0559 9.84 82.31 50.8 3 10-30-01 0600 1159 12.26 73.49 55.0 3 10-30-01 1200 1759 23.77 46.07 70.2 3 10-30-01 1800 2359 17.22 77.63 62.7 3 10-31-01 0000 0559 12.79 95.88 55.4 3 10-31-01 0600 1159 15.40 91.63 60.0 3 10-31-01 1200 1759 24.26 62.86 72.4 3 10-31-01 1800 2359 20.52 81.22 68.2 3 11-1-01 0000 0559 18.31 93.52 65.1 3 11-1-01 0600 1159 19.80 86.68 67.3 3 11-1-01 1200 1759 26.67 56.06 75.1 3 11-1-01 1800 2359 21.33 82.96 69.6 3 11-2-01 0000 0559 18.60 96.60 65.7 3 11-2-01 0600 1159 21.32 91.12 70.2 3 11-2-01 1200 1759 27.06 64.39 76.7 3 11-2-01 1800 2359 22.96 81.94 72.2 3 11-3-02 0000 0559 20.03 95.46 68.2 3 11-3-01 0600 1159 20.72 91.96 69.2

PAGE 94

82 Table A-2. Continued Period Date Time Frame, h Temp, C RH, % THI 2 3 11-3-01 1200 1759 27.26 64.53 77.0 3 11-3-01 1800 2359 21.57 86.59 70.3 3 11-4-01 0000 0559 18.93 98.37 66.4 3 11-4-01 0600 1159 20.95 91.48 69.6 3 11-4-01 1200 1759 24.32 73.24 73.6 3 11-4-01 1800 2359 20.27 85.81 68.0 3 11-5-01 0000 0559 18.57 87.48 65.3 3 11-5-02 0600 1159 17.20 81.23 62.8 3 11-5-01 1200 1759 19.30 50.86 64.7 3 11-5-01 1800 2359 13.61 76.83 57.0 3 11-6-01 0000 0559 7.74 93.43 46.7 3 11-6-01 0600 1159 11.13 77.93 53.1 3 11-6-01 1200 1759 21.63 39.00 66.9 3 11-6-01 1800 2359 13.52 73.43 56.9 3 11-7-01 0000 0559 6.09 95.02 43.6 3 11-7-01 0600 1159 9.53 81.23 50.4 3 11-7-01 1200 1759 23.21 25.97 67.7 3 11-7-01 1800 2359 14.08 71.20 57.8 3 11-8-01 0000 0559 8.83 91.99 48.6 3 11-8-01 0600 1159 13.54 83.40 56.9 3 11-8-01 1200 1759 25.04 38.89 71.0 3 11-8-01 1800 2359 16.92 74.81 62.2 3 11-9-01 0000 0559 10.40 93.84 51.3 3 11-9-01 0600 1159 13.38 84.40 56.6 3 11-9-01 1200 1759 25.53 37.72 71.5 3 11-9-01 1800 2359 16.64 70.76 61.7 1 Measure taken every 15 minutes. 2 Temperature-Humidity Index: (0.81 x dry bulb temperature in C) + ((relative humidity/100) x (dry bulb temperature 14.4)) + 46.6.

PAGE 95

83 Table A-3. Average temperature (Temp), relative humidity (RH), and temperature humidity index (THI) by period on collection days measured within the free stall barn at the Dairy Research Unit at Hague, Florida. Temp, C RH, % THI Period MIN MAX Mean MIN MAX Mean MIN MAX Mean 1 21.21 28.80 24.15 69.92 92.91 85.82 70.18 79.75 74.33 2 16.39 27.11 21.35 57.79 90.20 77.38 61.66 75.81 68.98 3 11.81 24.09 17.34 55.28 86.85 74.29 54.12 71.43 62.65 Table A-4. Average temperature (Temp), relative humidity (RH), and temperature humidity index (THI) by period on collection days measured outside the free stall barn at the Dairy Research Unit at Hague, Florida. Temp, C RH, % THI Period MIN MAX Mean MIN MAX Mean MIN MAX Mean 1 20.75 29.80 24.11 64.94 95.39 85.97 69.48 80.39 74.20 2 15.65 27.69 21.34 52.35 93.60 77.04 60.39 75.85 68.79 3 10.72 24.69 17.09 49.78 91.91 74.99 52.06 71.67 62.09 0.010.020.030.040.050.060.070.080.090.012345678910111213DAY OF COLLECTIONTHI MIN MAX Figure A-1. Minimum (MIN) and maximum (MAX) temperature humidity index (THI) recorded inside the free stall barn during each day of collection averaged across the three experimental periods. Average time of minimum THI was 0844 h. Average time of maximum THI was 1543 h.

PAGE 96

84 90.0 80.0 70.0 60.0 50.0 THI MIN MAX 40.0 30.0 20.0 10.0 0.0 1 2 3 12 13 4 5 6 7 8 9 10 11 DAY OF COLLECTION Figure A-2. Minimum (MIN) and maximum (MAX) temperature humidity index (THI) recorded inside the free stall barn during each day of collection of experimental period 1. Average time of minimum THI was 0814 h. Average time of maximum THI was 1552 h. 90.0 80.0 70.0 60.0 THI 50.0 MIN MAX 40.0 30.0 20.0 10.0 0.0 1 2 13 3 4 5 6 7 8 9 10 11 12 DAY OF COLLECTION Figure A-3. Minimum (MIN) and maximum (MAX) temperature humidity index (THI) recorded inside the free stall barn during each day of collection of experimental period 2. Average time of minimum THI was 0820 h. Average time of maximum THI was 1459 h.

PAGE 97

85 0.010.020.030.040.050.060.070.080.090.012345678910111213DAY OF COLLECTIONTHI MIN MAX Figure A-4. Minimum (MIN) and maximum (MAX) temperature humidity index (THI) recorded inside the free stall barn during each day of collection of experimental period 3. Average time of minimum THI was 0937 h. Average time of maximum THI was 1618 h. 0.010.020.030.040.050.060.070.080.090.012345678910111213DAY OF COLLECTIONTHI MIN MAX Figure A-5. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded outside the free stall barn during each day of collection averaged across the three experimental periods. Average time of minimum THI was 0828 h. Average time of maximum THI was 1459 h.

PAGE 98

86 0.010.020.030.040.050.060.070.080.090.012345678910111213DAY OF COLLECTIONTHI MIN MAX Figure A-6. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded outside the free stall barn during each day of collection of experimental period 1. Average time of minimum THI was 0751 h. Average time of maximum THI was 1449 h. 0.010.020.030.040.050.060.070.080.090.012345678910111213DAY OF COLLECTIONTHI MIN MAX Figure A-7. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded outside the free stall barn during each day of collection of experimental period 2. Average time of minimum THI was 0826 h. Average time of maximum THI was 1453 h.

PAGE 99

87 0.010.020.030.040.050.060.070.080.090.012345678910111213DAY OF COLLECTIONTHI MIN MAX Figure A-8. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded outside the free stall barn during each day of collection of experimental period 3. Average time of minimum THI was 0905 h. Average time of maximum THI was 1514 h. 55.566.577.5012345678 0% CFO 1.5% CFO 3.0% CFO*Hour after feedingRumen fluid pH Figure A-9. Hourly measurements of ruminal fluid pH of cows fed diets containing 0, 1.5, or 3.0% catfish oil (CFO) after feeding. Hour designated with an indicated treatment differences at P < 0.05 whereas those with a indicates treatment differences at P < 0.10

PAGE 100

LITERATURE CITED AbuGhazaleh, A. A., D. J. Schingoethe, A. R. Hippen, K. F. Kalscheur, and L. A. Whitlock. 2002. Fatty acid profiles of milk and rumen digesta from cows fed fish oil, extruded soybeans or their blend. J. Dairy Sci. 85:2266-2276. Adams, A. L., B. Harris, Jr., H. H. Van Horn, and C. J. Wilcox. 1995. Effects of varying forage types on milk production responses to whole cottonseed, tallow, and yeast. J. Dairy Sci. 78:573-581. Ahnadi, C. E., N. Beswick, L. Delbecchi, J. J. Kennelly, and P. Lacasse. 2002. Addition of fish oil to diets for dairy cows. II. Effects on milk fat and gene expression of mammary lipogenic enzymes. J. Dairy Res. 69:521-531. Allen, M. S. 2000. Effects of diet on short-term regulation of feed intake by lactating dairy cattle. J. Dairy Sci. 83:1598-1624. Association of Official Analytical Chemists, International. 1990. Official Methods of Analysis. 15th ed. AOAC, Arlington, VA. Avila, C. D., E. J. DePeters, H. Perez-Monti, S. J. Taylor, and R. A. Zinn. 2000. Influences of saturation ratio of supplemental dietary fat on digestion and milk yield in dairy cows. J. Dairy Sci. 83:1505-1519. Bancroft, T. A. 1968. Page 8 in Topics in Intermediate Statistics. Iowa State Univ. Press, Ames, IA. Bateman, H. G., J. N. Spain, and M. R. Ellersieck. 1996. Influence of by-product feeds and tallow on lactation performance of Holstein cows during two seasons. J. Dairy Sci. 79:114-120. Bauchart, D. 1993. Lipid absorption and transport in ruminants. J. Dairy Sci. 76:3864-3881. Bauchart, D., F. Legay-Carmier, M. Doreau, and B. Gaillard. 1990. Lipid metabolism of liquid-associated and solid-adherent bacteria in rumen contents of dairy cows offered lipid-supplemented diets. Brit. J. Nut. 63:563-578. Cant, J. P., E. J. DePeters, and R. L. Baldwin. 1991. Effect of dietary fat and postruminal casein administration on milk composition of lactating dairy cows. J. Dairy Sci. 74:211-219. 88

PAGE 101

89 Cant, J. P., E. J. DePeters, and R. L. Baldwin. 1993. Mammary uptake of energy metabolites in dairy cows fed fat and its relationship to milk protein depression. J. Dairy Sci. 76:2254-2265. Cant, J. P., A. H. Fredeen, T. MacIntyre, J. Gunn, and N. Crowe. 1997. Effect of fish oil and monensin on milk fat composition in dairy cows. Can. J. Anim. Sci. 77:125-131. Chilliard, Y. 1993. Dietary fat and adipose tissue metabolism in ruminants, pigs, and rodents: a review. J. Dairy Sci. 76:3897-3931. Chilliard, Y., and M. Doreau. 1997. Influence of supplementary fish oil and rumen-protected methionine on milk yield and composition in dairy cows. J. Dairy Res. 64:173-179. Chilliard, Y., A. Ferlay, R. M. Mansbridge, and M. Doreau. 2000. Ruminant milk fat plasticity: nutritional control of saturated, polyunsaturated, trans and conjugated fatty acids. Ann. Zootech. 49:181-205. Chilliard, Y., G. Gagliostro, J. Flechet, J. Lefaivre, and I. Sebastion. 1991. Duodenal rapeseed oil infusion in early and midlactation cows. 5. Milk fatty acids and adipose tissue lipogenic activities. J. Dairy Sci. 74:1844-1854. Coppock, C. E., and D. L. Wilks. 1991. Supplemental fat in high-energy rations for lactating cows: effects on intake, digestion, milk yield, and composition. J. Anim. Sci. 69:3826-3837. Dehority, B. A. 1984. Evaluation of subsampling and fixation procedures used for counting rumen protozoa. Appl. Environ. Microbiol. 48:182-185. DePeters, E. J., S. J. Taylor, C. M. Finley, and T. R. Famula. 1987. Dietary fat and nitrogen composition of milk from lactating cows. J. Dairy Sci. 70:1192-1201. Devendra, C., and D. Lewis. 1974. Fat in the ruminant diet: review. Indian J. Anim. Sci. 44 (12):917-938. Donovan, D. C., D. J. Schingoethe, R. J. Baer, J. Ryali, A. R. Hippen, and S. T. Franklin. 2000. Influence of dietary fish oil on conjugated linoleic acid and other fatty acids in milk fat from lactating dairy cows. J. Dairy Sci. 83:2620-2628. Doreau, M., and Y. Chilliard. 1997. Effects of ruminal or postruminal fish oil supplementation on intake and digestion in dairy cows. Reprod Nutr. Dev. 37:113-124. Drackley, J. K., and J. P. Elliot. 1993. Milk composition, ruminal characteristics, and nutrient utilization in dairy cows fed partially hydrogenated tallow. J. Dairy Sci. 76:183-196.

PAGE 102

90 Eastridge M. L., and J. L. Firkins. 1991. Feeding hydrogenated fatty acids and triglycerides to lactating dairy cows. J. Dairy Sci. 74:2610-2616. Elliot, J. P., J. K. Drackley, D. J. Schauff, and E. H. Jaster. 1993. Diets containing high oil corn and tallow of dairy cows during early lactation. J. Dairy Sci. 76:775-789. Getachew, G., E. J. DePeters, P. H. Robinson, and S. J. Taylor. 2001. In vitro rumen fermentation and gas production: influence of yellow grease, tallow, corn oil and their potassium soaps. Anim. Feed Sci. Technol. 93:1-15. Goering, H. K. and P. J. Van Soest. 1970. Forage Fiber Analysis (Apparatus, Reagents, Procedures, and Some Applications). Agric. Handbook No. 379. ARS-USDA, Washington, DC. Grummer, R. R., M. L. Luck, and J. A. Barmore. 1993. Rumen fermentation and lactation performance of cows fed roasted soybeans and tallow. J. Dairy Sci. 76:2674-2681. Hall, M. B. 1999, W. H. Hoover, J. P. Jennings, and T. K.Miller Webster. 1999. A method for partitioning neutral detergent-soluble carbohydrates. J. Sci. Food Agic. 79:2079-2086. Jenkins, T. C. 1993. Symposium: advances in ruminant lipid metabolism. J. Dairy Sci. 76:3851-3863. Jenkins, T. C. 2000. Feeding oleamide to lactating Jersey cows. 1. Effects on lactation performance and milk fatty acid composition. J. Dairy Sci. 83:332-337. Jenkins, T. C., J. A. Bertrand, and W. C. Bridges, Jr. 1998. Interactions of tallow and hay particle size on yield and composition of milk from lactating Holstein cows. J. Dairy Sci. 81:1396-1402. Jenkins, T. C., and B. F. Jenny. 1989. Effect of hydrogenated fat on feed intake, nutrient digestion, and lactation performance of dairy cows. J. Dairy Sci. 72:2316-2324. Jones, D. F., W. P. Weiss, and D. L. Palmquist. 2000. Short communication: influence of dietary tallow and fish oil on milk fat composition. J. Dairy Sci. 83:2024-2026. Jones, D. F., W. P. Weiss, D. L. Palmquist, and T. C. Jenkins. 1998. Dietary fish oil effects on milk fatty acid composition. J. Anim. Sci. 76 (Suppl 1):904 (Abstr.). Keady, T. W. J., C. S. Mayne, and D. A. Fitzpatrick. 2000. Effects of supplementation of dairy cattle with fish oil on silage intake, milk yield and milk composition. J. Dairy Res. 67:137-153. Lacasse, P., J. J. Kennelly, L. Delbecchi, and C. E. Ahnadi. 2002. Addition of protected and unprotected fish oil to diets for dairy cows. I. Effects on the yield, composition and taste of milk. J. Dairy Res. 69:511-520.

PAGE 103

91 Lewis, W. D., J. A. Bertrand, and T. C. Jenkins. 1999. Interaction of tallow and hay particle size on ruminal parameters. J. Dairy Sci. 82:1535-1537. Mackzulak, A. E., B. A. Dehority, and D. L. Palmquist. 1981. Effects of long-chain fatty acids on growth of rumen bacteria. Appl. Environ. Microbiol. 42:856-862. Malven, P. V., H. H. Head, R. J. Collier, and F. C. Buonomo. 1987. Periparturient changes in secretion and mammary uptake of insulin and concentrations of insulin and insulin-like growth factors in milk of dairy cows. J. Dairy Sci. 70:2254-2262. Markus, S. B., K. M. Wittenberg, J. R. Ingalls, and M. Undi. 1996. Production responses by early lactation cows to whole sunflower seed or tallow supplementation of a diet based on barley. J. Dairy Sci. 79:1817-1825. Martinez, N., E. J. DePeters, and D. L. Bath. 1991. Supplemental niacin and fat effects on milk composition of lactating Holstein cows. J. Dairy Sci. 74:202-210. Mertens, D. R., and L. O. Ely. 1982. Relationship of rate and extent of digestion to forage utilization-a dynamic model evaluation. J. Anim. Sci. 54:895-905. National Research Council. 2001. Nutrient Requirements of Dairy Cattle., 7 th rev. ed. Natl. Acad. Sci., Washington, DC. Nianogo, A. J., H. E. Amos, M. A. Frosestchel, and C. M. Keery. 1991. Dietary fat, protein degradability, and calving season: effects on nutrient use and performance of early lactation cows. J. Dairy Sci. 74:2243-2255. Nocek, J. E. 1988. In situ and other methods to estimate ruminal protein and energy digestibility: review. J. Dairy Sci. 71:2051-2069. Norman, H. D., R. H. Miller, J. R. Wright, and G. R. Wiggans. 2000. Herd and state means for somatic cell count from dairy herd improvement. J. Dairy Sci. 83:2782-2788. Oldick, B. S., C. R. Staples, W. W. Thatcher, and P. Gyawu. 1997. Abomasal infusion of glucose and fat-effect on digestion, production, and ovarian and uterine functions of cows. J. Dairy Sci. 80:1315-1328. Onetti, S. G., R. D. Shaver, M. A, McGuire, and R. R. Grummer. 2001. Effect of type and level of dietary fat on rumen fermentation and performance of dairy cows fed corn silage-based diets. J. Dairy Sci. 84:2751-2759. Onetti, S. G., R. D. Shaver, M. A, McGuire, D. L. Palmquist, and R. R. Grummer. 2002. Effect of supplemental tallow on performance of dairy cows fed diets with different corn silage:alfalfa silage ratios. J. Dairy Sci. 85:632-641. Palmquist D. L., and T. C. Jenkins. 1980. Fat in lactation rations: review. J. Dairy Sci. 63:1-14.

PAGE 104

92 Pantoja, J., J. L. Firkins, and M. L. Eastridge. 1996. Fatty acid digestibility and lactation performance by dairy cows fed fats varying in degree of saturation. J. Dairy Sci. 79:429-437. Pantoja, J., J. L. Firkins, M. L. Eastridge, and B. L. Hull. 1994. Effects of fat saturation and source of fiber on site of nutrient digestion and milk production by lactating dairy cows. J. Dairy Sci. 77:2341-2356. Pate, F. M. 1996. Value of fat in liquid feed. Page 42-48 in Proc. Seventh Annual Florida Ruminant Nutr. Symp., University of FL, Gainesville, FL. Ruppert, L. D., J. K. Drackley, D. R. Bremmer, and J. H. Clark. 2003. Effects of tallow in diets based on corn silage or alfalfa silage on digestion and nutrient use by lactating cows. J. Dairy Sci. 86:593-609. SAS. 1996. The SAS system for Windows, Release 6.12. SAS Institute, Inc. Cary, NC. Schneider, B. H., and W. P. Flatt. 1975. The indicator method. Page 168 in The Evaluation of Feeds Through Digestibility Experiments. Univ. Georgia Press, Athens. Shauff, D. J., J. P. Elliot, J. H. Clark, and J. K. Drackley. 1992. Effects of feeding lactating dairy cows diets containing whole soybeans and tallow. J. Dairy Sci. 75:1923-1935. Smith, W. A., B. Harris, Jr., H. H. Van Horn, and C. J. Wilcox. 1993. Effects of forage type on production of dairy cows supplemented with whole cottonseed, tallow, and yeast. J. Dairy Sci. 72:205-215. Soeldner, J. S., and D. Slone. 1965. Critical variables in radioimmunoassay of serum insulin using double antibody technich. Diabetes 14:771-777. Vagnoni, D. B., G. A. Broderick, M. K. Clayton, and R. D. Hatfield. 1997. Excretion of purine derivatives by Holstein cows abomasally infused with incremental amounts of purines. J. Dairy Sci. 80:1695-1702. Van Soest, P. J. 1994. Pages 260-261, 328-329 in Nutritional Ecology of the Ruminant. 2 nd edition. Cornell Univ. Press, Ithaca, NY. Weigel, D. J., J. P. Elliot, and J. H. Clark. 1997. Effects of amount and ruminal degradabiliy of protein on nutrient digestibility and production by cows fed tallow. J. Dairy Sci. 80:1150-1159. Whitlock, L. A., D. J. Schingoethe, A. R. Hippen, K. F. Kalscheur, R. J. Baer, N. Ramaswamy, and K. M. Kaesperson. 2002. Fish oil and extruded soybeans fed in combination increase conjugated linoleic acids in milk of dairy cows more than when fed separately. J. Dairy Sci. 85:234-243.

PAGE 105

93 Williams, C. H., D. J. David, and O. Iismaa. 1962. The determination of chromic oxide in feces samples by atomic absorption spectrophotometry. J. Agric. Sci. 59:381-385. Wu, Z., J. T. Huber, F. T. Sleiman, J. M. Simas, K. H. Chen, S. C. Chan, and C. Fontes. 1993. Effect of three supplemental fat sources on lactation and digestion in dairy cows. J. Dairy Sci. 76:3562-3570. Yang, C. M. J. 2002. Response of forage fiber degradation by ruminal microorganisms to branched-chain volatile fatty acids, amino acids, and dipeptides. J. Dairy Sci. 85:1183-1190.

PAGE 106

BIOGRAPHICAL SKETCH Alexandra Karina Amorocho Garcia was born in Rio de Janeiro, Brazil on January 22, 1977. At the age of 2 years she moved to Colombia, where she lived for 14 years. After finishing high school at age 16, she earned a full merit scholarship to study in the Escuela Agricola Panamericana (ZAMORANO) in Honduras, C.A. where she earned her Agronomy degree in 1996. From 1998 to 2000, she worked at the Dairy Research Unit of the University of Florida, Gainesville, FL; and worked on a Bachelor of Science degree in animal sciences. After completing her B.S. degree (dairy option) in December 2000, she started her graduate program under the supervision of Dr. Charles Staples in Dairy Cattle Nutrition. After graduation she plans to work hard to enhance the dairy industry in South America. 94


Permanent Link: http://ufdc.ufl.edu/UFE0000629/00001

Material Information

Title: Performance of Lactating Holstein Cows Fed Catfish Oil
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0000629:00001

Permanent Link: http://ufdc.ufl.edu/UFE0000629/00001

Material Information

Title: Performance of Lactating Holstein Cows Fed Catfish Oil
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0000629:00001


This item has the following downloads:


Full Text












PERFORMANCE OF LACTATING HOLSTEIN COWS FED CATFISH OIL


By

ALEXANDRA KARINA AMOROCHO GARCIA

















A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF
FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF MASTER OF SCIENCE

UNIVERSITY OF FLORIDA


2003























This thesis is dedicated to God and the most important people during my masters
program: my father, mother, sister, and Dr. Charles Staples. I would like to thank the
Lord God for giving me the opportunities and skills to attain this goal; and for support
throughout the trials in its attainment.

I would like to thank my father, Nelson Amorocho, for his love and guidance during his
life and after. I would like to thank my mother, Benilda Amorocho; and sister, Najesda
Amorocho, for helping and encouraging me, for inspiring me to do my best each and
every day, and for their love and support.

Finally, I thank my mentor Dr. Charles Staples for his endless patience and unconditional
help; and for giving me this great opportunity.















ACKNOWLEDGMENTS

I would like to acknowledge the supervisor of my committee, Dr. Charles R.

Staples, for accepting me into his research program, for his guidance, and for helping to

make this work a real success. I also would like to thank the members of my committee:

I thank Dr. Mary Beth Hall for giving me the opportunity to work hard and to reach my

goals; and I thank Dr. Lokenga Badinga for his assistance during this time. The

University of Florida, Department of Animal Sciences; Protein Products, Inc.

(Gainesville, GA); and U. S. Sugar Corp. (Clewiston, FL) supplied the resources needed

for this research, which I appreciate greatly. I am indebted to the staff of the Dairy

Research Unit (Hague, FL), with special thanks to Carrie Bradley for feeding the animals

during the study, and to all the employees of the farm who made this study possible. I

also would like to thank these students and friends: Najesda Amorocho, Ricardo Boger,

Sergio Burgos, Heidi Bissell, Colleen Larson, Lucia Holtshausen, and Jose Rossignoli,

who contributed to this research with their time and excellent effort. Gratitude is

extended to Jocelyn Jennings for her guidance and instruction in the dairy nutrition

laboratory. This research would not have been possible without the contributions of all.















TABLE OF CONTENTS

page

A C K N O W L E D G M E N T S ......... .................................................................................... iii

LIST OF TABLES .............................. ......... .... ..... .. .... ....... ....... vi

LIST OF FIGURES ............. .. ..... ...... ........ ....... .......................... viii

ABBREVIA TION S ............................................... .. .. .... .............. ....

ABSTRACT .............. .......................................... xi

CHAPTER

1 IN TR OD U CTION ............................................... .. ......................... ..

F atty A cid M etabolism ............. ......... ........ .......................... .....................
Sources and Composition of Fat in the Dairy Cow Diet ...........................................4

2 REVIEW OF THE LITERATURE ON FATS IN RUMINANT DIETS...................7

Effects of Yellow Grease in Ruminant Diets ........................... ....................7
Effects of YG and Tallow in Ruminant Diets .......................................................11
Effects of Tallow in Ruminant Diets ............................ .................................. 14
Effects of Tallow and Fish Oil in Ruminant Diets ............................................. 37
Effects of Fish Oil in Rum inant D iets .................................... .......... .................. 38

3 PERFORMANCE OF LACTATING HOLSTEIN COWS FED CATFISH OIL......46

Introdu action ...................................... ................................................. 4 6
M materials and M methods ....................................................................... ..................47
C ow s and D iets ................................................................................. 47
Collection of Sam ples and Analysis......................................... ............... 48
A parent D igestibility .......................................... .. .. .. ...... .......... 51
Rate and Extent of D igestion ...................................................... ..... .......... 51
Sampling and Analysis of Ruminal Fluid ........... ........ ....... ...........52
Statistical A analysis .......................... ............ ...........................53
R results and D iscu ssion .............................. ........................ .. ...... .... ...... ...... 55
D iet C om position............. .............. ........................................ .... .. ........ 55
Intake Response and Apparent Digestibility. ........................... ............... 55
In situ Dry Matter and Neutral Detergent Fiber Digestion ..............................58










Milk Production and Composition. ............................................ ............... 59
Fatty Acid Composition of Milk Fat. ...............................................................60
R um inal F erm entation. ........................................ ..........................................6 1
Blood Metabolites. ................................................... .. ...........................63
S u m m ary .................................64.............................

A P P E N D IX ...................................................................................................7 5

L IT E R A T U R E C IT E D ............................................................................. ....................88

BIOGRAPHICAL SKETCH ...................................................................... ..................94













































v















LIST OF TABLES


Table p

1-1. Average fatty acid profile of tallow, yellow grease, and marine fish oil. ...............5

3-1. Fatty acid profile of catfish oil. ........................................................................... 48

3-2. Ingredient and chemical composition of experimental diets containing catfish oil
(CFO) fed to lactating Holstein cows in summer ................................................65

3-3. Dry matter intake (DMI), apparent digestibility coeficients of DM, CP, NDF, ADF
and ether extract (EE), body weight change, and rectal temperatures (RT) of
lactating Holstein cows fed catfish oil (CFO) in summer ......................................66

3-4. In situ lag, rate, and extent of DM and NDF digestion of corn silage by lactating
Holstein cows fed catfish oil (CFO) in summer.....................................................67

3-6. Fatty acid composition of milk fat of lactating Holstein cows fed catfish oil (CFO)
in sum m er. ............................................................................68

3-7.Volatile fatty acid concentration, pH, microbial protein production, and protozoa
numbers in ruminal fluid and pH of urine and feces of lactating Holstein cows fed
catfish oil (CFO ) in sum m er ........................................................ ............... 69

3-8. Concentrations of plasma urea, glucose and insulin of lactating Holstein cows fed
catfish oil (CFO ) in sum m er ........................................................ ............... 69

A-1. Average temperature (Temp), relative humidity (RH), and temperature humidity
index (THI) in 6-h increments on collection days measured within the free stall
barn at the Dairy Research Unit at Hague, Florida. ............................................. 75

A-2. Average temperature (Temp),relative humidity (RH), and temperature humidity
index (THI) on 6-h increments on collection days measured outside the free stall
barn at the Dairy Research Unit at Hague, Florida. ............................................. 79

A-3. Average temperature (Temp), relative humidity (RH), and temperature humidity
index (THI) by period on collection days measured within the free stall barn at the
Dairy Research Unit at Hague, Florida. ...................................... ............... 83









A-4. Average temperature (Temp), relative humidity (RH), and temperature humidity
index (THI) by period on collection days measured outside the free stall barn at the
Dairy Research Unit at Hague, Florida. ...................................... ............... 83















LIST OF FIGURES


Figure page

3-1. Ruminal fluid pH for low milk producers and high milk producers fed 0, 1.5, and
3.0% catfish oil (C F O ).. ........................ .... .............. ........................... 70

3-2. Molar proportion of acetate in ruminal fluid for low milk producers and high milk
producers fed 0, 1.5, and 3.0% catfish oil (CFO)................... ........... ............... 70

3-3. Molar proportion of butyrate in ruminal fluid for low milk producers and high milk
producers fed 0, 1.5, and 3.0% catfish oil (CFO)................... ........... ............... 71

3-4. Molar proportion of isobutyrate in ruminal fluid for low milk producers and high
milk producers fed 0, 1.5, and 3.0% catfish oil (CFO).. .......................................71

3-5. Molar proportion of 2-methylbutyrate in ruminal fluid for low milk producers and
high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). ...............................72

3-6. Molar proportion of isovalerate in ruminal fluid for low milk producers and high
milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). ........................................72

3-7. Protozoa numbers in ruminal fluid for low milk producers and high milk producers
fed 0, 1.5, 3.0% catfish oil (CFO).............. ...... .............. ............................ 73

3-8. Urine pH for low milk producers and high milk producers fed 0, 1.5, and 3.0%
catfish oil (C F O )............. .... .......................................................... ......... ....... 73

3-9. Fecal pH for low milk producers and high milk producers fed 0, 1.5, and 3.0%
catfish oil (C F O )............. .... .......................................................... ......... ....... 74

A-1. Minimum (MIN) and maximum (MAX) temperature humidity index (THI)
recorded inside the free stall barn during each day of collection averaged across the
three experim ental periods. ........................................................... .....................83

A-2. Minimum (MIN) and maximum (MAX) temperature humidity index (THI)
recorded inside the free stall barn during each day of collection of experimental
p e rio d 1 .......................................................................... 8 4

A-3. Minimum (MIN) and maximum (MAX) temperature humidity index (THI)
recorded inside the free stall barn during each day of collection of experimental
p e rio d 2 .......................................................................... 8 4









A-4. Minimum (MIN) and maximum (MAX) temperature humidity index (THI)
recorded inside the free stall barn during each day of collection of experimental
p e rio d 3 .......................................................................... 8 5

A-5. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded
outside the free stall barn during each day of collection averaged across the three
experim mental periods. ................................................................... 85

A-6. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded
outside the free stall barn during each day of collection of experimental period 1..86

A-7. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded
outside the free stall barn during each day of collection of experimental period 2. 86

A-8. Minimum (MIN) and maximun (MAX) temperature humidity index (THI) recorded
outside the free stall barn during each day of collection of experimental period 3..87

A-9. Hourly measurements of ruminal fluid pH of cows fed diets containing 0, 1.5, or
3.0% catfish oil (CFO) after feeding. ............................... .. ........................ 87
















ABBREVIATIONS


ACC
ADF
AH
BH
BUN
CFO
CLA
CP
CS
CWG
DHA
DM
DMI
EE
EL
EPA
ESC
ESB
FA
FAS
FCM
FO
HAS
HCS
HOC
HRDP
HYG
LCFA
LL
LPL
LRDP
NDF
OM
PF
PFO
PHT
SCC


SCD
SCS
TG
TMR
UFO
VFA
WCS
YG
WSB


steroyl-CoA desaturase
somatic cell score
triglycerides
total mixed ration
unprotected fish oil
volatile fatty acid
whole cottonseed
yellow grease
whole soybeans


acetyl-Co A carboxylase
acid detergent fiber
alfalfa hay
bermudagrass hay
blood urea nitrogen
catfish oil
conjugated linoleic acid
crude protein
corn silage
choice white grease
docosahexaenoic acid
dry matter
cry matter intake
ether extract
early lactation
eicosapentaenoic acid
ethanol soluble carbohydrate
extruded soybeans
fatty acids
fatty acid synthase
fat corrected milk
fish oil
high alfalfa silage
high corn silagle
high oil corn
high ruminally degradable protein
hydrogenated yellow grease
long chain fatty acid
late lactation
lipoprotein lipase
low ruminally degradable protein
neutral detergen fiber
organic matter
prilled fatty acids
protected fish oil
partially hydrogenated tallow
somatic cell count














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

PERFORMANCE OF LACTATING HOLSTEIN COWS FED CATFISH OIL
By

Alexandra Karina Amorocho Garcia

May 2003

Chair: Charles R. Staples
Major Department: Animal Sciences

The objective of this study was to evaluate catfish oil as a dietary ingredient for

lactating Holstein cows. Twelve multiparous Holstein cows (six fitted with a cannula in

the rumen and six intact) were assigned to the experiment at an average of 195 + 27 days

in milk. Catfish oil was suspended in liquid molasses (27% of DM), mixed with grain,

and fed as a totally mixed ration at 0, 1.5, and 3% of dietary DM. The fatty acid profile

of catfish oil was primarily 18.7% palmitic, 4.9% palmitoleic, 5.0% stearic, 47% oleic,

14% linoleic, 1.1% eicosapentaenoic, and 3.1% docosahexaenoic acids. Dietary

treatments were arranged in a 3 x 3 Latin square design replicated four times. Each

period lasted 27 days (14 days for adaptation to a new diet and 13 days for data

collection). Milk production and dry matter intake were measured daily. Blood was

collected on Days 26 and 27. Urine and fecal samples were collected and measured for

pH on Days 22 and 23. Rumen fluid was collected hourly for 8 hours on Day 15.

Apparent digestibility of nutrients was calculated by the marker ratio technique. In situ

DM and NDF digestibility of corn silage were measured on Days 25, 26, and 27. Intake









of dry matter increased linearly (P = 0.01) as intake of catfish oil increased (23.0, 24.4,

and 25.4 kg/d). Production of milk was unchanged by the feeding of catfish oil (29.0,

29.0, and 29.4 kg/d). Concentrations of milk fat (3.57, 3.60, and 3.48%) and protein

(3.21, 3.18, and 3.23%) were unchanged by feeding catfish oil. Concentrations of plasma

glucose (57.8, 55.1, and 56.0 mg/100 mL) and urea nitrogen (11.6, 11.0, and 12.0 mg/100

mL) were not affected by dietary treatments. The pH of urine (8.05, 8.05, and 8.06) and

feces (6.69, 6.71, and 6.68) were unchanged by feeding increasing amounts of catfish oil.

Average ruminal fluid pH decreased linearly (P = 0.0001) (6.40, 6.20, and 6.15), as did

the molar proportions of acetate (P = 0.02) (64.5, 64.2, and 63.4%). The molar

proportions of propionate increased linearly (P = 0.02) (19.4, 20.0, and 20.4%) as did

those of butyrate (P = 0.08) (12.0, 12.4, and 12.5%) as intake of catfish oil increased.

Ruminal protozoa numbers were unchanged by treatments. Apparent digestibility

coefficients of DM, CP, NDF, and ADF were improved as intake of catfish oil increased.

In situ lag, rate and extent of corn silage DM digestion were similar across dietary

treatments. However, in situ digestion rate of NDF was increased linearly (P = 0.04) as

intake of catfish oil increased (0.023, 0.024, and 0.029 h-1). Mixing catfish oil with liquid

molasses at up to 3% of dietary dry matter stimulated dry matter intake and digestibility

of lactating Holstein cows but did not alter lactation performance.














CHAPTER 1
INTRODUCTION

In general, energy intake is a primary limitation on milk yield for high producing

dairy cows and is determined by the net energy concentration of the diet and dry matter

intake (Allen, 2000). During periods of heat stress, a decrease in energy intake followed

by a decrease in milk production is a routine response. To minimize the loss of milk

production and still meet the nutrient requirement of the animal, the energy density of the

diet may be increased. Dietary fatty acids can be an ideal feed ingredient during heat

stress periods because fats have a greater energy density than other feeds, are used with a

high efficiency, and produce less heat during digestion compared to other major

feedstuffs (NRC, 2001).

Fatty Acid Metabolism

Lipid metabolism in the rumen is characterized by rapid lipolysis, fatty acid

hydrogenation and de novo lipid cellular synthesis by microorganisms (Bauchart et al.,

1990). Microbial cleavage of the glycerol molecule from the individual fatty acids

(lipolysis) occurs with dietary glycolipids, phospholipids, and triglycerides (Chilliard et

al., 2000). Lipolytic bacteria rapidly carry out this process of hydrolysis in the rumen.

Protozoa may not be capable of lipolytic activity (Palmquist and Jenkins, 1980).

Minimal loss of fatty acids from the rumen occurs either by absorption across the ruminal

epithelium or by catabolism to volatile fatty acids (VFA) or CO2 (Jenkins, 1993).

Unsaturated free fatty acids have relatively short half-lives in ruminal contents because

they are rapidly hydrogenated by microbes to more saturated fatty acids (Jenkins, 1993).









Polyunsaturated fatty acids are first isomerized and then hydrogenated. For example,

linoleic acid (cis-9, cis-12 C18:2) is isomerized to conjugated linoleic acid (CLA) (cis-9,

trans- 11 C18:2); and then hydrogenated first to transvaccenic acid (trans 11 C18:1) and

then to stearic acid (C18:0). Biohydrogenation of unsaturated fatty acids depends on the

nature and amount of dietary lipids; the efficacy and type of technological treatment of

feedstuffs; and the nature and amount of forage, concentrates, and minerals in the diets

that influence either the microbial ecosystem, the transit rate of digesta, or the interaction

of fatty acids with digestion (Chilliard et al., 2000). The rate oflipolysis and

biohydrogenation is sensitive to pH, being reduced at lower ruminal pH. First, lipolysis

is limited and thus biohydrogenation which can only occur on free fatty acids (Chilliard

et al., 2000). In addition, dietary fatty acids can be incorporated into cellular lipids of

ruminal bacteria and protozoa and thus pass out of the rumen in an unsaturated form.

Also microbes can synthesize fatty acids de novo from carbohydrate precursors (Jenkins,

1993). Total lipid content of bacterial dry mass in the rumen ranges from 10 to 15%

(Jenkins, 1993), and proportions are lower in liquid-associated bacteria than in

solid-associated bacteria (Bauchart et al., 1990).

Lipids reaching the duodenum consisted of fatty acids from both dietary and

microbial origins. Fatty acids of less than 14 carbons are absorbed by brush border cells

of the small intestine and enter the blood directly (Palmquist and Jenkins, 1980). Long

chain fatty acids (> C16) are incorporated into micellar solution by bile salts and

lysolecithin. Micelles are disrupted on the surface of the microvilli on the intestinal

mucosa and free fatty acids are taken up by the mucosal cell. Absorbed free fatty acids

are reesterified in the mucosal cell into triglycerides. Triglycerides are packaged along









with phospholipids, cholesterol esters and apolipoproteins into chylomicrons or very low

density lipoproteins that are then transported to the lymphatic circulation and blood

vessels (Bauchart, 1993). Milk fat triglycerides are synthesized either from fatty acids

that are taken up from the blood or by de novo synthesis by the mammary gland. The

mammary gland uses plasma nonesterified fatty acids released from adipose tissue or

long chain fatty acids available from the diet as a source of long chain fatty acids because

of the inability of the mammary gland to convert C16:0 to C18:0 by chain elongation.

Most of the fatty acids arising from de novo synthesis are saturated, short to

medium chain fatty acids (C4:0 to C16:0). Long chain fatty acids (LCFA) are potent

inhibitors of short chain fatty acid synthesis by the mammary gland through a direct

inhibitory effect on acetyl CoA carboxylase activity, which often results in a decrease in

the percentage of medium chain fatty acids (C8:0 to C14:0) in milk fat (Chilliard et al.,

2000) during lipid supplementation.

Addition of fat to dairy cow diets has been associated with changes in ruminal

fermentation, mainly depressions in fiber digestion. Devendra and Lewis (1974)

postulated that reduced digestibility could be caused by prevention of microbial

attachment by physical coating of the fiber with fat. Supplemental fats may have an

inhibitory effect on microbial activity (Palmquist and Jenkins, 1980) especially on

cellulotic strains of bacteria where long chain fatty acids (LCFA) may interfere with

nutrient uptake by the bacteria (Maczulack et al., 1981). However this is not always the

case because gram positive-methanogenic bacteria were inhibited by LCFA addition thus

depressing methane production, whereas cellulolytic bacteria were not affected

(Devendra and Lewis, 1974). Addition of cellulose to LCFA-containing culture media,









alleviated the cell surface interaction of bacteria with LCFA (Maczulack et al., 1981).

Also the presence of cations like calcium and magnesium may form mineral soaps with

fat (Devendra and Lewis 1974) allowing normal nutrient uptake by the microbes.

Despite the potential negative effect of fat supplementation on ruminal fermentation, fat

continues to be a mainstay in diets for dairy cows.

Sources and Composition of Fat in the Dairy Cow Diet

Some reasons to include fats in the diets of ruminants are that they provide a source

of concentrated energy, act as carriers of fat-soluble vitamins, may increase palatability,

may reduce dustiness in the feed, may reduce feed wastage, may increase feed efficiency,

and may decrease frictional wear of mixing machinery (Devendra and Lewis, 1974).

Diets made up of forages and grains for ruminants generally contain between 2 and

5% ether-extractable compounds (of which about one-half are fatty acids and the other

half are nonnutritive waxes, cutins, chlorophyll, etc.) (Chilliard, 1993). In lactating cows,

fatty acid output in the milk usually exceeds daily intake of fatty acids (Palmquist and

Jenkins, 1980). Dietary fatty acids can be incorporated directly into milk fat. The

remaining fatty acids in milk (mainly 14 carbons and shorter) are synthesized de novo

from acetic and butyric acids produced by ruminal microorganisms. Fats in diets for the

lactating dairy cow can be from vegetable (forages, oils, and seeds) and animal (tallow,

lard, and fish oils) sources. Supplemental fats can have different fatty acid profiles that

differ according to chain length and number of double bonds. Linoleic acid (C18:2)

predominates in most seeds, whereas linolenic acid (C18:3) is usually the most common

fatty acid in forages. An important exception to this generalization is the very high

concentration of C18:3 (57%) in linseed oil (Palmquist and Jenkins, 1980). The most

commonly used sources of pure fats are tallow and yellow grease. Average fatty acid









composition of tallow and yellow grease are similar except that yellow grease contains

less C18:0 and more C18:2 (Table 1-1). Marine fish oil contains many of the fatty acids

found in tallow and yellow grease but also some that are unique to products derived from

the ocean, namely eicosapenteanoic acid (EPA) and docosahexaenoic acid (DHA) (Table

1-1).

Table 1-1. Average fatty acid profile of tallow, yellow grease, and marine fish oil.
Fatty acid Tallow' Yellow grease2 Marine fish oil3
Myristic (C14:0), % 2.9 2.0 7.2
Palmitic (C16:0), % 25.3 21.1 15.5
Palmitoleic (C16:1), % 3.3 4.2 7.5
Stearic (C18:0), % 18.0 11.3 3.0
Oleic (C18:1), % 43.3 43.5 11.9
Linoleic (18:2), % 3.8 13.9 1.1
Linolenic (C18:3), % 0 0 1.7
Eicosapentaenoic (20:5), % 0 0 13.8
Docosapentaenoic (22:5), % 0 0 2.0
Docasahexaenoic (22:6), % 0 0 9.1
Average of values reported by Adams et al. (1995), Avila et al. (2000), Elliot et al.
(1993), Getachew et al. (2001), Grummer et al. (1993), Jenkins et al. (1998), Lewis et al.
(1999), Oldick et al. (1997), Onetti et al. (2001), Onetti et al. (2002), Pantoja et al.
(1996), Ruppert et al. (2003), Shauff et al. (1992), and Wu et al. (1993).
2 Average of values reported by Avila et al. (2000), DePeters et al. (1987), Jenkins and
Jenny (1989), Martinez et al. (1991), and Oldick et al. (1997).
3 Average of values reported by AbuGhazaleh et al. (2002), Chilliard and Doreau (1997),
Donovan et al. (2000), Doreau and Chilliard (1997), Keady et al. (2000), and Whitlock et
al. (2002).

In the search for fat supplements to use in dairy cows diets, preliminary work in

Florida indicated that mixing catfish oil with liquid molasses dramatically improved

intake of the liquid supplement by beef cows on rangeland (F. M. Pate, personal

communication). Catfish oil has not been evaluated as a feedstuff for dairy cows.

Because catfish are fresh water fish, their fatty acid profile differs from that of marine

fish in that omega-3 fatty acids, EPA and DHA, are in lower concentrations. This is

because pond-raised fresh water fish consume less algae, the source of omega-3 fatty






6


acids. Feeding marine fish oil to cows has improved milk production but can decrease

dry matter intake (Chilliard and Doreau, 1997; Keady et al., 2000). If catfish oil can

improve feed intake as it did with beef cows, then it may prove to be a very effective

energy supplement for increasing milk production. Because catfish oil has a fatty acid

profile similar to that of tallow and yellow grease, the effects of feeding tallow and

yellow grease on lactating dairy cow performance are included in the literature review in

the next section.














CHAPTER 2
REVIEW OF THE LITERATURE ON FATS IN RUMINANT DIETS

Effects of Yellow Grease in Ruminant Diets

Jenkins and Jenny (1989) fed eight lactating Holstein cows yellow grease (YG) or

hydrogenated YG (HYG). The fatty acid composition of YG was 2.5% C14:0, 25.5%

C16:0, 14.7% C18:0, 43.4% C18:1, and 8.0% C18:2. The fatty acid composition of HYG

was 1.7% C14:0, 21.6% C16:0, and 75.6% C18:0. The concentrates contained the fat

sources with fats replacing a portion of the corn. Corn silage was the source of forage

(55% of dietary DM). Dietary treatments were control diet (no added fat), 5% YG, 3%

HYG, and 5% HYG. Feeding YG decreased DM intake compared to the control and

HYG diets (22.9, 20.5, 22.5, and 23.5 kg of DM for control, 5% YG, 3% HYG, and 5%

HYG, respectively). Milk yield of fat-supplemented cows were unchanged but tended (P

= 0.07) to be greater for cows fed the 5% HYG diet (32.0, 31.5, 31.9, and 33.6 for

control, 5% YG, 3% HYG, and 5% HYG, respectively). Milk fat percentage was

decreased by YG but increased when 5% HYG was fed (3.50, 2.83, 3.34 and 3.74% for

control, 5% YG, 3% HYG, and 5% HYG, respectively). Milk protein percentage was

decreased by the fat supplements but was not different among the cows fed the fat-

supplemented diets (3.20, 3.07, 3.17, and 3.09% for control, 5% YG, 3% HYG, and 5%

HYG, respectively). Plasma glucose tended (P 0.10) to be greater for cows fed the fat

supplements. Apparent DM digestibility was greater by cows fed YG (70.0, 72.0, 69.6,

and 68.7% for control, 5% YG, 3% HYG, and 5% HYG, respectively), whereas apparent

digestibility of acid detergent fiber (ADF) was depressed similarly in cows fed









supplemental fat (31.6, 21.6, 18.9, and 20.0 for control, 5% YG, 3% HYG, and 5% HYG,

respectively). Ruminal fluid of cows fed YG contained a greater molar proportion of

propionate (26.2 vs. 21.9 mol/100mol), isovalerate (2.0 vs. 1.6 mol/100 mol), and

valerate (2.0 vs. 1.6 mol/100 mol), but less acetate (57.7 vs. 61.8 mol/100 mol), butyrate

(10.5 vs. 12.2 mol/100 mol), and acetate to propionate ratio (2.2 vs. 2.9 mol/100 mol)

than ruminal fluid of cows fed HYG.

Martinez et al. (1991) fed eight lactating Holstein cows YG, whole cottonseed

(WCS), and niacin. The fatty acid composition of YG was 3.4% C14:0, 24.3% C16:0,

14.1% C18:0, 42.1% C18:1, and 10.0% C18:2. The fatty acid composition of whole

cottonseed was 2.3% C14:0, 23.5% C16:0, 2.5% C18:0, 17.3% C18:1, and 53.2% C18:2.

Dietary treatments were the following (DM basis): 1) 2% fat, no niacin, 2) 4% fat, no

niacin, 3) 2% fat with 0.055% niacin, and 4) 4% fat with 0.055% niacin. The 2% fat

diets contained fatty acids from whole cottonseed, whereas the 4% fat diets contained 2%

of the fatty acids from whole cottonseed and 2% of the fatty acids from YG. The forage

source was chopped alfalfa hay (40% of dietary DM). Dry matter intake and milk protein

percentage were not affected by either niacin or fat supplementation. Percentage of milk

fat tended (P = 0.10) to increase in cows fed diets containing 2% YG (3.29 vs. 3.42%) as

did milk yield (30.8 vs. 31.5 kg/d). As a result, milk fat yield was increased by feeding

YG (1.01 vs. 1.07 kg/d). No differences for dependent variables were detected due to

niacin. Proportions of short and medium-chain fatty acids (C6:0 to C16:0) of milk fat

were decreased and the proportion of long-chain fatty acids (C18:0, C18:1, and C18:3)

were increased, except C18:2 which was decreased by supplementing YG.









DePeters et al. (1987) fed twelve lactating Holstein cows YG. Cows were

subdivided into two status categories based on stage of lactation. Groups consisted of

cows in early (EL) and late (LL) lactation. The fatty acid composition of YG was

2.4% C14:0, 17.9% C16:0, 12.1% C18:0, 46.8% C18:1, and 12.8% C18:2. Dietary

treatments were 0, 3.5, or 7% added YG (DM basis). The forage source was chopped

alfalfa hay (50% of dietary DM). Yellow grease replaced a portion of the cracked corn in

the concentrate. Dry matter intake was greater for cows fed diets containing YG (140.8,

155.3, and 148.0 kg/wk for 0, 3.5, and 7% YG, respectively). Milk yield was greater for

cows fed diets containing YG (200.3, 237.4, and 223.5 kg/wk for 0, 3.5, and 7% YG,

respectively). Percentage of milk fat was depressed from cows fed the 7% YG diet

compared with those fed the 0 and 3.5% YG diets (3.45, 3.47, and 3.04% for 0, 3.5, and

7% YG, respectively). Percentage of milk protein was depressed by including YG at 3.5

or 7% (3.33, 3.21, and 3.21% for 0, 3.5, and 7% YG, respectively). The fatty acid

composition of milk was affected when cows were YG. Proportions of short-chain and

medium-chain fatty acids (C6:0 to C16:0) were depressed whereas long-chain fatty acids

(C18:0 and C18:1) were elevated by feeding YG. Apparent digestibilities of DM, NDF,

and ADF were not affected by YG, however, apparent digestibility of ether extract was

increased.

Cant et al. (1991) fed four lactating primiparous cows, fitted with a rumen cannula,

diets of 50% forage and 50% concentrate (DM basis). The forage source was chopped

alfalfa hay. Dietary treatments were 0 or 4% YG (DM basis). Yellow grease replaced a

proportion of the corn and barley. Dry matter intake was not affected but apparent DM

digestibility was reduced by YG (71.3 vs. 68.1% for 0 and 4% YG, respectively). Milk









production was improved 14% with YG (23.8 vs. 27.1 kg/d). Milk fat percentage (3.5 vs.

3.7%) and milk fat yield (0.8 vs. 1.0 kg/d) were improved with the addition of YG. Milk

protein percentage was lower when YG was added (3.15 vs. 3.0%) but milk protein yield

was unchanged. Dry matter and NDF digestibilities were reduced by dietary YG.

Cant et al. (1993) fed YG to four lactating primiparous cows fitted with rumen

cannulas. Diets were 50% chopped alfalfa hay and 50% concentrate (DM basis) with YG

at 0 or 4% of dietary DM. Milk yield and fat percentage were not affected by YG. A

small but statistically significant drop in plasma glucose concentration was detected with

added dietary YG (0.81 vs. 0.73 mM for 0 and 4% YG diets, respectively). Milk protein

percentage was depressed by YG addition (3.3 vs. 3.1%). Milk fatty acid proportions of

C6:0 to C16:0 were decreased whereas those of C 18:0 and C18:1 were increased by YG

addition.

Nianogo et al. (1991) utilized twelve multiparous Holstein cows calving in fall and

twelve multiparous Holstein cows calving in summer from calving to 17 wk postpartum.

The forage source was wheat silage offered in ad libitum amounts separate from

concentrate. Two sources of protein used were soybean meal serving as a high ruminally

degradability protein (HRDP) source and a mixture of heated soybean meal and corn

gluten meal serving as a low ruminally degradability protein (LRDP) source. The forage

to concentrate ratios were 23.5:76.5 in fall and 28.1:71.9 in summer (DM basis). Dietary

treatments were the following (% of dietary DM): 1) 0% YG with HRDP, 2) 0% YG with

LRDP, 3) 5.3% YG with HRDP, and 4) 5.3% YG with LRDP. Addition of YG to the

diet had no influence on DMI, milk production, 4% FCM production, or percentages and

yields of milk fat and milk protein. Cows receiving YG lost more BW than control cows









(2.6 vs. 24.4 kg/16 wk). Digestibility of DM (68.0 vs. 70.1%) and CP ( 57.4 vs. 64.5%)

were greater whereas digestibility of NDF (59.3 vs. 55.2%) was lower in cows receiving

YG. Part of the depression in apparent CP digestion caused by feeding LRDP was

alleviated by adding YG to diets containing LRDP (YG by RDP interaction; 61.3, 53.4,

66.6, and 62.3% for 0% YG-HRDP, 0% YG-LRDP, 5.3% YG-HRDP, and 5.3% YG-

LRDP, respectively).

Effects of YG and Tallow in Ruminant Diets

Avila et al. (2000) fed four ruminally and duodenally cannulated midlactation

Holstein cows tallow, YG or a blend of tallow and YG. The fatty acid composition of

tallow was 3.7% C14:0, 27.3% C16:0, 19.3% C18:0, 41.0% C18:1, and 3.5% C18:2. The

fatty acid composition of YG was 1.0% C14:0, 21.3% C16:0, 6.1% C18:0, 41.5% C18:1,

and 21.4% C18:2. All diets contained 12% whole cottonseed. The control diet was

4.2% ether extract (DM basis). All diets contained 45% alfalfa hay (DM basis) and the

supplemental fat replaced a portion of the corn and barley. Treatments were the

following: no supplemental fat (control, 3% total fatty acids, DM basis), 2% tallow,

2% YG, or 2% blend (60% tallow: 40% YG). Dry matter intakes were maintained by

cows fed the supplemental fats compared to the control cows and did not differ due to fat

source. Milk yield (32.7 vs. 35.2 kg/d) and milk fat yield (1.19 vs. 1.25 kg/d) increased

with fat supplementation relative to control. Milk protein and fat concentrations were

unchanged across treatments. The ruminal and total tract digestibilities of the fiber

fractions were unaffected by the addition and source of added fat to diets. Total VFA

concentrations and ruminal pH were unaffected but proportion of butyrate was decreased

by fat supplementation. Feeding the fat blend decreased ruminal pH (6.27, 6.31, and

6.14) and the acetate to propionate ratio (3.14, 3.13, and 2.97) for tallow, YG, and fat









blend, respectively compared to cows fed the single sources of fat. Plasma glucose

concentration decreased linearly with increasing proportions of YG in the fat supplement

(69.6, 68.5,and 67.7 mg/dl for tallow, blend, and YG, respectively).

Oldick et al. (1997) utilized four ruminally cannulated multiparous Holstein cows

in a 4 x 4 Latin square designed experiment. The four treatments consisted of abomasal

infusions of 1) water (control), 2) 1 kg/d of glucose, 3) 0.45 kg/d of tallow, and 4)

0.45 kg/d of YG. The fatty acid composition of tallow was 2.7% C14:0, 25.4% C16:0,

22.4% C18:0, 36.2% C18:1, and 2.1% C18:2. The fatty acid composition of YG was

0.8% C14:0, 16.6% C16:0, 9.5% C18:0, 43.8% C18:1, and 17.4% C 18:2. The cows

were fed a TMR containing 25.8% corn silage, 11.2% cottonseed hulls, and

63% concentrate. Dry matter intake was not affected by infusate treatments. Mean milk

production was not affected by treatments, although mean 4% FCM production tended

(P < 0.12) to be greater when fats were infused than when glucose was infused (26.1,

25.5, 27.7, and 27.8 kg/d for water, glucose, tallow, and YG, respectively). Mean milk

fat percentage tended (P < 0.10) to increase when fat was infused relative to glucose

infusion (3.0 2.9, 3.2, and 3.1% for water, glucose, tallow, and YG, respectively).

Infusing YG reduced milk protein percentage compared to tallow (3.1 vs. 2.9%).

Apparent digestibilities of DM, OM, and CP in the total tract were not affected by

infusates. Total tract apparent digestibility of ADF was decreased when glucose, tallow,

and YG were infused abomasally relative to the water infusion (54.8, 51.6, 53.2, and

51.8% for water, glucose, tallow, and YG, respectively). Apparent NDF digestibility

tended (P = 0.12) to decrease in cows with the YG infusion relative to those with the

infusion of tallow (59.0 vs. 57.7%). Plasma concentration of glucose (69.8 vs.









63.2 mg/dl) and insulin (1.33 vs. 0.78 ng/ml) were greater in cows receiving the glucose

infusion than in those receiving fat infusion.

Getachew et al. (2001) evaluated YG, tallow and corn oil on in vitro VFA

concentration and on true digestibility. A simulated TMR was prepared using beet pulp

(7.1%), soybean meal (6.9%), barley grain (18%), corn grain (18%), and alfalfa hay

(50%) (% of substrate DM). The fatty acid composition of tallow was 2.2% C14:0,

21.4% C16:0, 16.1% C18:0, 29.3% C18:1, and 3.5% C18:2. The fatty acid composition

of YGwas 1.0% C14:0, 15.9% C16:0, 9.0% C18:0, 31.3% C18:1, and 11.0% C18:2. The

fatty acid composition of corn oil was 9.2% C16:0, 1.7% C18:0, 23.9% C18:1, and

48.1% C18:2. Addition of YG, tallow, or corn oil had no effect on in vitro true

digestibility of the DM or on total VFA production. However all fat sources decreased

acetate and isovalerate but increased propionate productions resulting in a reduction of

the acetate to propionate ratio. Production of butyrate and valerate were not affected by

the inclusion of YG, tallow, or corn oil.

In summary, addition of YG as supplemental fat in the lactating dairy cow diet

decreased (Jenkins and Jenny, 1989), had no effect (Martinez et al., 1991; Cant et al.,

1991; Nianogo et al., 1991; Avila et al., 2000; Oldick et al., 1997) or increased DMI

(DePeters et al., 1987; Cant et al. 1991). Yellow grease may have depressed DMI due to

inhibition of ruminal fermentation or due to an effect on palatability. Milk yield of cows

supplemented with YG was unchanged (Jenkins and Jenny, 1989; Cant et al., 1993;

Nianogo et al., 1991; Oldick et al., 1997) or improved (Martinez et al. 1991, DePeters et

al., 1987; Cant et al., 1991; Avila et al., 2000). Milk fat percentage of cows fed diets

containing YG increased (Cant et al., 1991; Avila et al., 2000), decreased (Jenkins and









Jenny, 1989); or was unchanged (Cant et al., 1993; Nianogo et al., 1991). Proportions of

short-chain (C6:0 to C16:0) fatty acids in milk fat were decreased (Martinez et al.,

1991;DePeters et al., 1987; Cant et al., 1993) and the proportions of long-chain fatty

acids (C18:0 and C18:1) were increased (Martinez et al., 1991; DePeters et al., 1987;

Cant et al., 1993). Milk protein percentage was decreased (Jenkins and Jenny, 1989;

Cant et al., 1991; Cant et al., 1993), or was unaffected (Martinez et al., 1991; DePeters et

al., 1987; Nianogo et al., 1991, Avila et al., 2000) by YG addition. Concentration of

plasma glucose decreased with YG consumption (Cant et al., 1993; Avola et al., 2000).

Ruminal fluid of cows fed YG contained similar concentrations of total VFA (Getachew

et al., 2001; Avila et al., 2000), a greater molar proportion of propionate (Jenkins and

Jenny, 1989; Getachew et al., 2001), a lower molar proportion of acetate (Jenkins and

Jenny, 1989; Getachew et al., 2001), and a lower acetate to propionate ratio (Jenkins and

Jenny, 1989; Avila et al., 2000) compared to control cows. Apparent DM digestibility

was greater (Jenkins and Jenny, 1989; Nianoge et al., 1991), not affected (DePeters et al.,

1987) or reduced (Cant et al., 1991) by YG feeding whereas apparent digestibility of fiber

was depressed (Jenkins and Jenny, 1989; Nianogo et al., 1991) or not affected (DePeters

et al., 1987).

Effects of Tallow in Ruminant Diets

Ruppert et al. (2003) fed multiparous Holstein cows fitted with a ruminal cannula

supplemental tallow. The fatty acid composition of tallow was 2.3% C14:0,

24.2% C16:0, 17.4% C18:0, 43.4% C18:1, and 5.3% C18:2. The forage sources were

corn silage and alfalfa silage. The diets were 50% forage (DM basis). Dietary treatments

were high corn silage (HCS) (40:10 corn silage to alfalfa silage) or high alfalfa silage

(HAS) (10:40 corn silage to alfalfa silage) and contained 0, 2 or 4% tallow (% of dietary









DM). Intake of DM decreased linearly with increasing tallow supplementation,

regardless of forage type. Cows fed the HAS diets consumed less DM (22.6, 21.4, and

21.4 kg/d) than those fed the HCS diets (24.8, 23.6, and 22.9 kg/d for 0, 2, and

4% tallow, respectively). Milk yield was not affected when tallow was supplemented to

the diet. Milk fat percentage tended (P = 0.06) to decrease linearly as dietary tallow

supplementation to HCS diets increased (3.18, 2.89, and 2.70% for 0, 2, and 4% tallow

diets, respectively) whereas it was unchanged when supplemented to HAS diets (3.39,

3.44, and 3.41% for 0, 2, and 4% tallow diets, respectively) (forage source by tallow

interaction). Yield of 3.5% FCM and yield of CP in milk was not affected by tallow

supplementation. Percentage of CP in milk tended (P = 0.13) to decrease linearly as

dietary tallow increased for both forage sources (3.12, 2.99, and 3.00% for 0, 2, and

4% tallow diets, respectively). The composition of milk fat was altered as tallow was

supplemented to diets. Short- and medium-chain FA in milk (C6:0 to C10:0 and C14:0 to

C15:0) decreased linearly as tallow supplementation increased. Concentrations of C12:0

and C16:0 decreased quadratically as tallow supplementation increased. Stearic acid

concentration in milk fat increased by addition of 2% tallow but was not increased further

by 4% tallow (quadratic effect of tallow). Concentration of C18:1 increased linearly as

tallow supplementation increased. The content of C18:2 in milk fat decreased linearly as

tallow supplementation increased. The pH and concentration of total VFA in ruminal

fluid were not affected by tallow supplementation. Molar proportions of acetate and

butyrate decreased linearly and the molar proportion of propionate increased linearly with

increasing tallow supplementation. The apparent digestibility coefficients for DM, CP,

NDF and ADF were not affected by tallow supplementation. Digestion coefficients of









EE increased quadratically with increasing tallow supplementation. This increase tended

to be (P < 0.06) less dramatic for cows fed HCS diets (69.1, 79.6, and 85.7% for 0, 2, and

4% tallow diets, respectively) compared to cows fed HAS diets (58.3, 76.8, and 81.8%

for 0, 2, and 4% tallow diets, respectively) (quadratic effect of tallow by forage

interaction). This maybe attributed to the higher content of non-FA lipid in EE from

alfalfa silage compared with corn silage. Concentrations of plasma glucose and plasma

urea nitrogen were not affected by tallow supplementation.

Shauff et al. (1992) fed four multiparous Holstein cows fitted with a ruminal

cannula a TMR of 45% alfalfa haylage, 5% corn silage and 50% concentrate (DM basis).

The four dietary treatments were the following: 1) control, no added fat, 2) 10% raw

whole soybeans (WSB), 3) 10% WSB plus 2.5% tallow, 4) 10%WSB plus 4% tallow

(DM basis). The fatty acid composition of tallow was 3.2% C14:0, 24.8% C16:0,

14.5% C18:0, 45.9% C18:1, and 5.9% C18:2. The fatty acid composition of raw WSB

was 0.1% C14:0, 11.3% C16:0, 3.6% C18:0, 21.6% C18:1, and 55.4% C18:2. Intake of

DM and production of milk were not affected by supplemental fat. Milk fat percentage

tended (P < 0.06) to increase when fat was fed to the cows, especially when both tallow

and WSB were fed (3.34, 3.41, 3.56, and 3.52% for control, WSB, WSB + 2.5% tallow,

and WSB + 4% tallow, respectively). As a result of increased milk fat concentration,

milk fat yield tended (P < 0.06) to increase when cows were fed fat (1.02, 1.05, 1.08, and

1.05 kg/d for control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively).

Yields and percentages of milk protein were not affected by treatments. Adding fat to the

diets decreased the concentration of C6:0, C8:0, C10:0, C12:0, C14:0, C14:1, and C15:0

in milk fat. The milk fatty acids, C6:0, C8:0, C10:0, C12:0 and C14:0, decreased further









when tallow was added to the diets. Concentration of C16:0 in milk fat was decreased by

fat supplementation, however decreases were less when tallow was added to the diets

(27.7, 23.6, 25.4, and 25.9 for control, WSB, WSB + 2.5% tallow, and WSB + 4%

tallow, respectively). Concentration of C18:0 in milk fat was increased by including

supplemental fat in the diet, however increases were less when tallow was added to the

diets especially at 4% of the diet (8.3, 11.4, 11.0, and 10.0 g/100g for control, WSB,

WSB + 2.5% tallow, and WSB + 4% tallow, respectively). The concentration of C18:1

in milk fat was increased by supplemental fat, the greatest increase occurring when both

tallow and WSB were included in the diet (21.0, 25.2, 28.3, and 29.3 g/100g for control,

WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively). Supplementing fat to

the diet did not affect C18:2 concentration in milk, but adding tallow with diets

containing WSB decreased the C18:2 concentration in milk when compared with adding

only WSB. Concentrations of total VFA in ruminal fluid were decreased by feeding fat,

especially when both tallow and WSB were fed (116.4, 115.5, 108.4, and 109.1 mM for

control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively). Molar

proportions of acetate tended to decrease (65.0, 64.1, 63.8, and 62.6 mol/100 mol for

control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively) and molar

proportions of propionate tended to increase (18.8, 20.0, 20.4, and 21.4 mol/100 mol for

control, WSB, WSB + 2.5% tallow, and WSB + 4% tallow, respectively) in ruminal fluid

when fat was fed. These shifts resulted in decreased acetate to propionate ratios for cows

fed fat (3.5, 3.3, 3.2, and 2.9 for control, WSB, WSB + 2.5% tallow, and WSB + 4%

tallow, respectively). Ruminal fluid pH and molar proportions of butyrate, isovalerate,

and valerate were not affected by treatment. Apparent total tract digestibilities of DM









(65.9, 64.1, 63.7, and 64.1% for control, WSB, WSB + 2.5% tallow, and WSB + 4%

tallow, respectively) and CP (67.3, 61.1, 61.2, and 63.1 for control, WSB, WSB + 2.5%

tallow, and WSB + 4% tallow, respectively) decreased when fat was added to the diets,

whereas digestibilities of ADF and NDF were not affected by fat addition.

Concentrations of plasma glucose and urea nitrogen were not different among treatments.

Smith et al. (1993) fed 36 Holstein cows increasing concentrations of alfalfa hay in

diets containing corn silage, whole cottonseed (WCS), tallow, and yeast. Twelve dietary

treatments were used in a 3 by 4 factorial design. Three corn silage to alfalfa hay ratios

were fed, namely, 50:0, 37.5:12.5, and 25:25 (% of dietary DM). Four dietary

concentrations of tallow and WCS were fed, namely, 0 and 0, 2.5 and 0, 0 and 12, and 2.5

and 12 (% of dietary DM). Intake of DM was not affected by tallow supplementation.

Cows fed tallow produced 3.1% more milk than those not fed tallow averaged across all

dietary forage ratios (23.2 vs. 22.5 kg/d). Milk fat percentage tended to be depressed

when tallow was added to diets containing only corn silage (3.33 vs. 3.15%) but tended to

be increased when tallow was added to diets containing both corn silage and alfalfa hay

(3.27 vs. 3.58%) (tallow by corn silage vs. alfalfa hay interaction, P = 0.08). The

3.5% FCM yield (P = 0.07), milk protein yield (P = 0.09), and BW change (P = 0.06)

tended to increase with tallow supplementation. The concentration of C6:0 to C15:0 fatty

acids and C18:2 in milk fat were decreased when tallow was fed, whereas C16:1 and

C18:1, and C18:2 were increased. Increasing alfalfa hay in the diets had no effect on

milk fatty acid composition. Digestibility of DM (59.65 vs. 63.85%) and NDF (52.78 vs.

59.96%) tended to be lower with corn silage plus tallow diets than for alfalfa hay plus

tallow diets. The EE digestibility was greater for tallow diets than for diets without









tallow (88.10 vs. 79.05%). Treatments had no effect on blood urea nitrogen

concentrations.

Eastridge and Firkins (1991) fed five primiparous Holstein cows hydrogenated

tallow fatty acids (FA) or tallow triglycerides (TG). The fatty acid composition of the

hydrogenated tallow was 2.8% C14:0, 29.0% C16:0, 52.8% C18:0, and 11.2% C18:1.

The fatty acid composition of the tallow triglycerides was 1.5% C14:0, 21.6% C16:0,

59.2% C18:0, and 15.6% C18:1. Fat supplements replaced a portion of the corn. Forage

sources were alfalfa silage (26.3% of dietary DM) and corn silage (26.3% of dietary

DM). Dietary treatments were the following: control (no supplemental fat), 2% tallow

FA, 5% tallow FA, 2% tallow TG, and 5% tallow TG (% of dietary DM). Intake of DM

was similar between control cows and those fed tallow. However DMI increased as

tallow FA increased from 2 to 5% of the diet but decreased as tallow TG increased from

2 to 5% of the diet (fat source by fat inclusion rate interaction, P = 0.03). Milk

production was greater for cows fed fat compared to controls (28.2, 30.2, 30.5, 29.3, and

30.4 kg/d for control, 2% tallow FA, 5% tallow FA, 2% tallow TG, and 5% tallow TG,

respectively). Yields of 4% FCM were greater for cows fed fat compared to controls

(25.7, 28.4, 30.2, 26.6, and 28.1 kg/d for control, 2% tallow FA, 5% tallow FA,

2% tallow TG, and 5% tallow TG, respectively). Percentage of milk protein was not

affected by treatments. Cows fed FA produced milk of greater fat percentage than those

fed TG (3.76 vs. 3.45%) and cows fed tallow at 5% tended (P = 0.10) to have greater

percentages of milk fat compared to those fed tallow at 2% of dietary DM (3.69 vs.

3.52%). The apparent digestibility of DM and OM tended to be lower when diets were

supplemented with fat. A greater DM digestibility depression was observed when cows









were fed tallow in the FA form than in the TG form (62.3 vs. 66.8%). Digestibility of

NDF was unchanged by treatments. Body weight was not different among treatments.

Lewis et al. (1999) fed four nonlactating ruminally cannulated Holstein cows to

determine the effects of dietary tallow and hay particle length. Diets contained 25%

alfalfa hay, 25% corn silage, and 50% concentrate (dietary DM basis). Tallow replaced

a portion of the ground corn in the concentrate at 4.8% of dietary DM. Dietary

treatments were the following: 1) 0% tallow, short-cut hay (1.3% > 3.3 cm), 2) 0%

tallow, long-cut hay (19.6% > 3.3 cm), 3) 5% tallow, short-cut hay, or 4) 5% tallow,

long-cut hay. The fatty acid composition of tallow was 3.1% C14:0, 25.2% C16:0,

15.3% C18:0, 45.1% C18:1, and 3.9% C18:2. Dry matter intake was restricted to 85% of

ad libitum amounts. Total tract DM, NDF, and ADF apparent digestibilities were not

affected by tallow supplementation to the diet. Total tract CP digestibility tended

(P = 0.07) to increase with tallow supplementation (70.2 vs. 74.7%). No hay by tallow

interactions were observed for total tract digestibilities. In situ digestibilities of TMR

DM (P < 0.15), NDF (P < 0.09), and ADF (P < 0.13) at 24 h tended to be depressed by

the addition of tallow. After 48 h of ruminal incubation, tallow decreased the

digestibilities of DM (56.6 vs. 61.3%) and ADF (22.5 vs. 29.1%), and tended (P = 0.06)

to depress NDF digestibility (27.8 vs. 32.5%). No tallow by hay length interaction after

24 or 48 h of in situ incubation were detected for DM, NDF, ADF, and CP digestibilities.

Ruminal pH increased when tallow was added to the diet that contained long-cut hay, but

decreased when tallow was added to the short cut hay diet (6.52, 6.59, 6.60, and 6.54 for

0% tallow, long-cut hay, 5% tallow, long-cut hay, 0% tallow, short-cut hay,, and 5%

tallow, short cut hay, respectively) (hay length by tallow interaction, P = 0.07). Tallow









decreased ruminal concentrations of acetate (68.5 vs. 70.1 mol/100 mol), increased

concentrations of propionate (17.3 vs. 15.4 mol/100 mol), increased concentrations of

isobutyrate (1.2 vs. 1.0 mol/100 mol), increased concentrations of valerate (1.2 vs.

1.1 mol/ 100 mol), and decreased acetate to propionate ratio (4.0 vs. 4.6). Butyrate

content in ruminal fluid was not affected by treatments. No hay length by tallow

interactions for individual VFA were detected.

Jenkins et al. (1998) fed Holstein cows from calving to 18 wk postpartum to

determine the effects of tallow and hay particle size on lactation performance. Diets

consisted of 25% alfalfa hay, 25% corn silage, and 50% concentrate (dietary DM basis).

Tallow replace a portion of the corn. The fatty acid composition of tallow was

3.2% C14:0, 29.2% C16:0, 24.7% C18:0, 62.2% C18:1, and 2.5% C18:2. Dietary

treatments were the following: 1) 0% tallow, long-cut hay (19.6% > 3.3 cm), 2) 0%

tallow, short-cut hay (1.3% > 3.3 cm), 3) 5% tallow, long-cut hay, and 4) 5% tallow,

short-cut hay. Intake of DM was unchanged by tallow supplementation. Milk yield was

greater for cows fed tallow compared to cows not fed tallow (36.5 vs. 33.2 kg/d). Milk

fat percentage tended (P = 0.12) to decrease with tallow supplementation (3.19 vs.

3.39%). Milk protein percentage was reduced by the addition of tallow (2.97 vs. 3.11%).

As a result, energy- corrected milk production was increased when tallow was added to

diets containing short-cut hay (35.0 vs. 30.9 kg/d) but was unchanged when added to

diets containing long-cut hay (33.5 vs. 33.5 kg/d) (tallow by hay length interaction). A

tendency (P 0.10) for an interaction of tallow by hay particle length was observed for

fat yield in that tallow had no effect on fat yield when added to the long-cut hay (1.13 vs.

1.16 kg/d) but milk fat yield increased when tallow was added to the short-cut hay (1.18









vs. 1.04 kg/d). Protein yield however was increased by the addition of tallow (1.09 vs.

1.01 kg/d). Samples of ruminal fluid were collected via stomach tube twice during the

18 wk study. No effect of tallow or hay particle size was detected on molar proportions

of ruminal VFA. Body weight change tended (P 0.15) to be greater for cows fed

tallow than for cows fed without tallow (41.2 vs. 26.7 kg/18 wk).

Adams et al. (1995) fed forty multiparous and primiparous Holstein cows 12

dietary treatments arranged in a 3 x 4 factorial design. The four forage treatments were

the following: 1) 45% corn silage (CS), 2) 33.75% corn silage and 11.25% alfalfa hay

(CS + AH), 3) 33.75% corn silage and 11.25% bermudagrass hay (CS + BH), and 4)

33.75% corn silage and 11.25% cottonseed hulls (CS + CSH) (dietary DM basis). The

three fat treatments were the following: 1) no added fat, 2) 12.5% whole cottonseed

(WCS), and 3) 2.5% tallow. The fatty acid composition of tallow was 2.7% C14:0,

23.6% C16:0, 16.5% C18:0, 43.7% C18:1, and 5.0% C18:2. Cows fed tallow produced

more milk than those fed WCS but not any more than cows unsupplemented with fat

(26.4, 25.4, and 26.5 kg/d for tallow, WCS, and unsupplemented cows, respectively).

Addition of fat had no effect on DMI, milk yield, milk protein percentage, milk fat

percentage, or BW change, however, when tallow was the source of fat, milk yield

increased when compared to yields of cows fed WCS (26.4 vs. 25.4 kg/d). Milk fat %

was decreased by addition of fat to CS (3.44 vs. 3.65%) or AH (3.39 vs. 3.69%) diets but

milk fat was increased with fat addition to BH diets (3.53 vs. 3.37%) ((fat vs. no fat) by

(BH vs. AH + CS) interaction, P = 0.036). Milk protein percentage of cows fed BH was

lower when fed tallow than when fed WCS (2.98 vs. 3.19%) whereas milk protein









percentage of cows fed CS + AH or CS alone was lower when fed WCS than when fed

tallow (3.00 vs. 3.09%) ((tallow vs. WCS) by (BH vs. AH + CS interaction), P = 0.038).

Drackley and Elliott (1993) fed four Holstein cows partially hydrogenated tallow

(PHT) at 0, 2, 4, and 6% of dietary DM. Tallow replaced ground shelled corn. Diets

contained 3.3, 5.1, 7.3, and 9.0% total fatty acids. The fatty acid composition of the PHT

was 1.6% C14:0, 26.9% C16:0, 39.2% C18:0, 29.9% C18:1, and no detected C18:2.

Milk production, milk fat yield, milk protein yield, and DMI were not affected by PHT.

However percentage of milk protein was decreased in cows fed PHT when compared to

control cows (3.02, 2.82, 2.86, and 2.85% for cows fed 0, 2, 4, and 6% PHT diets).

Percentages of short and medium-chain fatty acids in milk fat decreased linearly, whereas

percentages of C18:1 increased with increasing dietary PHT (18.8, 23.1 24.8 and

27.5 g/100 g of fat for cows fed 0, 2, 4, and 6% PHT diets). Ruminal pH, molar

concentrations of VFA, and acetate to propionate ratio did not differ among treatments.

Total tract apparent digestibilities of DM, OM, NDF, ADF, and ether extract were not

affected by feeding PHT.

Elliott et al. (1993) fed four ruminally fistulated lactating Holstein cows diets

containing high oil corn (HOC) grain and tallow. Cows were fed diets of alfalfa haylage

and concentrate (37:63, DM basis). The fatty acid composition of tallow was

3.2% C14:0, 24.8% C16:0, 14.5% C18:0, 45.9% C18:1, and 5.9% C18:2. The fatty acid

composition of the high oil corn was 13.4% C16:0, 2.2% C18:0, 29.5% C18:1, and

51.4 C18:2. Treatments were the following: 1) control, no added fat, 2) high oil corn

grain replacing regular corn grain, 3) high oil corn grain plus 2.5% tallow, and 4) high oil

corn grain plus 5% tallow (dietary DM basis). Dry matter intake was not affected by









supplementing fat, although DMI tended (P = 0.10) to be lower when cows were fed the

diet containing HOC and 5% tallow (27.2, 27.1, 26.8, and 23.8 kg/d for control, HOC,

HOC+ 2.5% tallow, and HOC + 5.0% tallow). Milk production was not different among

treatments. Percentage of protein in milk was lower when cows were fed diets containing

fat and tended (P = 0.13) to be lower for cows fed diets containing tallow compared with

diets containing only HOC (3.04, 2.98, 2.87, and 2.80% for control, HOC, HOC+ 2.5%

tallow, and HOC + 5.0% tallow). Milk fat percentage tended (P = 0.07) to be lower

when cows were fed diets containing tallow (3.30, 3.33, 3.06, and 2.82% for control,

HOC, HOC+ 2.5% tallow, and HOC + 5.0% tallow), although yields of milk fat were not

different among treatments. Total VFA concentrations in ruminal fluid were lower when

cows were fed diets containing fat and were lower when cows were fed the HOC plus 5%

tallow diet compared with the HOC plus 2.5% tallow diet (133.4, 128.3, 129.2 and

122.0 mM for control, HOC, HOC+ 2.5% tallow, and HOC + 5.0% tallow). The molar

proportion of acetate decreased (60.5, 61.8, 60.3,and 59.4 for control, HOC, HOC+ 2.5%

tallow, and HOC + 5.0% tallow) and the molar proportion of propionate tended (P =

0.10) to increase (26.7, 25.7, 26.7,and 27.5 for control, HOC, HOC+ 2.5% tallow, and

HOC + 5.0% tallow) in ruminal fluid when cows were fed diets containing tallow. Molar

proportions of isovalerate were increased when cows were fed the 5% tallow diet.

Ruminal pH and molar proportions of butyrate and valerate were not altered by treatment.

Total tract apparent digestibilities of DM, ADF and NDF were not different among

treatments.

Pantoja et al. (1996) fed fifty lactating Holstein cows tallow or PHT to observe the

effect of fats varying in degree of saturation. Diets contained 50% forage (50:50 alfalfa









and corn silages, DM basis). The fatty acid composition of tallow was 2.3% C14:0,

22.7% C16:0, 17.8% C18:0, 38.8% C18:1, and 3.2% C18:2. The fatty acid composition

ofPHT was 1.5% C14:0, 23.0% C16:0, 52.2% C18:0, 14.5% C18:1, and no detectable

C18:2. Dietary treatments were a basal diet (control) with no added fat (2.9% EE) and

four diets with 5% added fat from tallow, tallow plus PHT in a 2:1 proportion, tallow plus

PHT in a 1:2 proportion, and PHT. Dry matter intake tended (P = 0.07) to be lower for

cows fed diets supplemented with fat than for those fed the control diet; however DMI

increased linearly with increased degree of fat saturation (25.2, 23.1, 23.8, 24.8, and

24.7 kg/d for control, tallow, tallow + PHT, PHT + tallow, and PHT, respectively). Milk

production increased due to fat supplementation (35.6, 40.6, 36.9, 39.3, and 38.0 kg/d for

control, tallow, tallow + PHT, PHT + tallow, and PHT, respectively). Milk fat

percentage was not affected by fat supplementation when compared to controls, but cows

fed increasing amounts of PHT had increasing concentrations of milk fat (3.63, 3.17,

3.48, 3.56, and 3.77% for control, tallow, tallow + PHT, PHT + tallow, and PHT,

respectively). Milk protein percentage was unchanged by supplemental fat when

compared to the control diet, however cows fed PHT had a higher milk protein

percentage than did cows fed tallow (3.05, 2.86, 3.03, 2.98, and 3.02% for control,

tallow, tallow + PHT, PHT + tallow, and PHT, respectively). Cows fed the control diet

lost more BW than did cows supplemented with fat, but no effect of fat source on BW

change was detected.

Pantoja et al. (1994) utilized six primiparous lactating Holstein cows that were

cannulated in the rumen, duodenum and ileum. Forage consisted of a 60:40 mix of corn

and alfalfa silages. Six dietary treatments were the following: 1) control (C) with no









added fat, 20% soyhulls (SH), and 40% forage, 2) 5% PHT, 20% SH, and 40% forage

(PHT-SH), 3) 5% tallow, 20% SH, and 40% forage (tallow-SH), 4) 5% blend of tallow

and canola oil (TC), 20% SH, and 40% forage (TC-SH), 5) 5% TC, no SH, and 40%

forage [(LF) low forage] (TC-LF), and 6) 5% TC, no SH, and 60% forage [(HF) high

forage] (TC-HF). The fatty acid composition of PHT was 2.2% C14:0, 26.7% C16:0,

52.6% C18:0, 14.2% C18:1, and no detectable C18:2. The fatty acid composition of

tallow was 2.5% C14:0, 24.8% C16:0, 1.1% C18:0, 43.8% C18:1, and 4.9% C18:2. The

fatty acid composition of TC was 1.3% C14:0, 14.9% C16:0, 9.6% C18:0, 49.6% C18:1,

and 14.6% C18:2. Dry matter intake was not affected by inclusion of supplemental fat in

diets when compared to the control diet, but DMI decreased linearly as fat unsaturation

increased (19.8, 20.8, 18.8, and 17.8 kg/d for C, PHT-SH, tallow-SH, and TC-SH,

respectively). Milk fat production and percentage were similar for cows on C or fat-

supplemented diets. Milk protein percentage was reduced by fat supplementation (3.06,

2.91, 2.98, and 2.82 for C, PTH-SH, tallow-SH, and TC-SH, respectively). Ruminal pH

was not affected by fat supplementation. The different percentages of effective fiber in

TC diets (TC-LF, TC-SH, and TC-HF) did not influence the pH of the ruminal fluid.

Total VFA concentration decreased with fat supplementation when compared to the

control diet. The molar percentages of acetate, propionate, butyrate, or branched-chain

VFA were not affected by fat supplementation. Ruminal acetate: propionate was higher

when soyhulls replaced forage NDF because of the higher digestibility of soyhulls in the

rumen and total tract. Kinetics of in situ NDF digestion of alfalfa silage and SH were not

influenced by fat supplementation or fat saturation. Lag time (2.1, 0.6, and 1.7 h for

TC-LF, TC-SH, and TC-HF, respectively) as well as residual alfalfa silage NDF (38.5,









37.2, 36.9% for TC-LF, TC-SH, and TC-HF, respectively) responded in a quadratic

manner with percentage of effective fiber in TC diets. Cows fed TC-LF had a longer lag

time and a greater residual NDF than did cows fed TC-SH or TC-HF.

Wu et al. (1993) fed twenty-four Holstein cows in their midlactation a diet

consisting of 39% alfalfa hay, 7.2% whole cottonseed, 5.1% cottonseed hulls and 48%

concentrate (DM basis). Dietary treatments were control (C) with no supplemental fat,

2) 2.5% tallow, 3.0% Ca salts of palm fatty acids (CS), or 2.5% prilled fatty acids (PF)

(dietary DM). The fatty acid composition of tallow was 3.8% C14:0, 29.1% C16:0,

15.9% C18:0, 44.4.2% C18:1, and 2.7% C18:2. The fatty acid composition of CS was

1.5% C14:0, 51.5% C16:0, 4.1% C18:0, 35.5% C18:1, and 7.4% C18:2. The fatty acid

composition ofPF was 3.4% C14:0, 45.7% C16:0, 42.8% C18:0, 7.1% C18:1, and no

detectable C18:2. Dry matter intake did not differ among treatments. Milk yields were

increased by supplemental fat (31.6, 33.9, 32.9, and 34.2 kg/d for C, tallow, CS, and PF,

respectively). Milk fat percentage did not differ among treatments, but fat yields were

greater for the cows receiving the fat supplements (1.02, 1.10, 1.11, and 1.15 kg/d for C,

tallow, CS, and PF, respectively). Milk protein percentage was lower for cows receiving

the fat supplements (3.13, 3.05, 2.97, and 3.01% for C, tallow, CS, and PF, respectively).

Supplementation of dietary fat increased the percentages of C16:0 and C18:0 but

decreased the percentages of C6:0 to C14:0 in milk fat. Plasma glucose concentrations

were not affected by fat supplementation. Apparent digestibilities of DM, CP, ADF and

NDF were not affected by overall fat supplementation. However, DM (64.4, 62.8, and

61.8%) and ADF (37.0, 32.1, and 30.9%) digestibilities were greater for diets containing

tallow compared to those containing CS or PF.









Markus et al. (1996) fed eighteen primiparous and thirty-one multiparous lactating

Holstein cows tallow or whole sunflower seeds. Diets contained 12% corn silage,

14% alfalfa silage, 9% alfalfa hay, and 65% concentrate based on barley. The

experimental diets were the following: 1) control at 1.8% EE, 2) 2.7% tallow, and

3) 7.1% whole sunflower seeds (dietary DM basis). Dry matter intake of cows was not

influenced by tallow or whole sunflower seeds. Mean production of milk and 4% FCM

were not affected by treatments (34.4, 35.5, and 34.6 kg/d and 30.0, 31.6, and 29.9 kg/d

for control, tallow and sunflower, respectively). The production and concentrations of

milk protein and fat were not influenced by supplemental fat. Concentrations of the C6:0

to C16:0 fatty acids in milk fat were lower compared to that coming from cows fed the

control diet. Tallow supplementation resulted in greater concentrations of C18:0, C18:1,

and C20:0 fatty acids in milk fat compared to those from cows fed the control diet. The

concentrations of individual or total VFA in the ruminal fluid were not influenced by

feeding tallow or whole sunflower seeds. Change in BW was not influenced by

supplemental tallow or whole sunflower seeds.

Onetti et al. (2001) fed fifteen ruminally cannulated midlactation Holstein cows

tallow or choice white grease (CWG). The fatty acid composition of tallow was

2.8% C14:0, 24.8% C16:0, 19.8% C18:0, 42.7% C18:1, and 3.3% C18:2. The fatty acid

composition of CWG was 1.4% C14:0, 23.8% C16:0, 10.9% C18:0, 47.6% C18:1, and

11.7% C18:2. Dietary treatments were 0% supplemental fat (control), 2% tallow,

2% CWG, 4% tallow, and 4% CWG (DM basis). The forage to concentrate ratio was

50:50 (DM basis). Corn silage was the sole forage source. Fat replaced part of the

cracked corn and soybean meal in the concentrate portion the fat-supplemented diets.









Compared with the control diet, the dietary NDF concentration was 4 and 7 percentage

units lower for the 2 and 4% fat diets (34.0 for control, 29.95 for 2% fat diets and 27.25

for 4% fat diets) probably because a lower inclusion of soybean hull NDF with each

increase in added fat. Fatty acid concentration was 3.0% for control, 4.3 and 4.4% for

2% tallow and CWG, and 6.9 and 5.6% for the 4% tallow and CWG treatments. Cows

fed supplemental fats consumed 2 kg/d less DM than control cows (24.2 vs. 26.3 kg/d).

Cows fed the 4% fat diets tended (P = 0.08) to consume less DM than those fed the 2%

fat diets (23.7 vs. 24.6 kg/d). Milk production decreased with fat supplementation and

was most pronounced for cows receiving 4% fat in the diet (42.3, 41.1 and 38.1 kg/d for

control, 2% fat, and 4% fat, respectively). The same response was observed for 4% FCM

yield (37.8, 36.5 and 31.8 kg/d for control, 2% fat, and 4% fat respectively). Cows

consuming fat-supplemented diets produced milk of lower fat percentage than cows fed

the control diet (2.9 vs. 3.3%) and less milk fat than cows fed the control diet (1.1 vs.

1.4 kg/d). Production of milk fat was decreased when CWG increased from 2 to 4% of

diet (1.20 vs. 1.08 kg/d), but was unchanged when tallow increased from 2 to 4% of diet

(1.10 vs. 1.12 kg/d) (fat source by fat concentration interaction). Milk fat percentage

increased when tallow increased from 2% to 4% of diet (2.83 vs. 3.00%), but decreased

when CWG increased from 2 to 4% of diet (2.93 vs. 2.85%) (fat source by fat

concentration interaction). Milk protein yield decreased with the increased concentration

of supplemental fat (1.33 and 1.26 kg/d for the 2 and 4% fat treatments, respectively).

Milk protein percentage tended to increase (P < 0.06) with the level of fat

supplementation (3.29 vs. 3.33% for the 2 and 4% fat treatments, respectively). Relative

percentage of milk fatty acids having 14 or fewer carbons was decreased with









supplemental fat (24.0, 19.5, and 18.2 g/100 g of fatty acids for control, 2% fat and 4%

fat, respectively). This reduction tended (P < 0.09) to be more pronounced in milk from

cows fed CWG than those fed tallow (18.2 vs. 19.2 g/100 g of fatty acids). Including fat

in the diets increased the milk fat concentration of C18:0 (8.4 vs. 9.1 g/100 g of fatty

acids) and this increment was more marked for cows fed CWG that for those fed tallow

(9.3 vs. 9.0 g /100 g of fatty acids). The C18:1 percentage in milk fat increased when fat

was supplemented compared to the control group (29.1 vs. 24.9 g/100 g of fatty acids).

Concentrations ofC18:2 (5.10 vs. 3.75 g/100 g of fatty acids) and C18:3 (0.35 vs.

0.25 g/100 g of fatty acids) were decreased when fat was added to the diets. Tallow

supplementation decreased C18:2 to a greater extent than did CWG (3.6 vs. 3.9 g/100 g

of fatty acid for tallow and CWG, respectively). The proportion of cis 9, trans-11

conjugated linoleic acid (CLA) was decreased (0.47 vs. 0.40 g/100 g of fatty acids),

whereas the proportion of the trans-10, cis 12 CLA isomer was not affected when

supplemental fat was fed. Concentration of milk fat C18:1 isomers, both cis-9 and cis-11

isomers, were increased by fat supplementation. The trans-10 isomer increased when fat

was added to the diets, and it was higher in milk fat from CWG-fed cows than from

tallow-supplemented cows (1.20, 2.19 and 1.98 g/100 g of fatty, respectively). The trans-

11 isomer concentration of milk fat decreased with fat supplementation and was lower for

cows fed CWG than for those fed tallow (0.73, 0.42 and 0.52 g/100 g of fatty acid,

respectively). Adding supplemental fat at 4% of dietary DM reduced trans-11 proportion

relative to the 2% level of fat supplementation. Ruminal fluid pH and total VFA

concentration were not affected by fat supplementation. The molar proportion of ruminal

acetate decreased (58.0 vs. 52.0 mol/100 mol), and the molar proportion of propionate









increased (22.9 vs. 30.4 mol/100 mol) when feeding supplemental fat. The acetate to

propionate ratio (A:P) decreased due to fat supplementation (2.56 vs. 1.75 mol/100 mol).

The A:P decreased at the 4% fat supplementation rate relative to that of the 2% fat

treatment (1.6 vs. 1.9 mol/100 mol). Fat supplementation reduced protozoa numbers per

ml of rumen fluid and the reduction was most severe at the highest level of fat

supplementation (7.5, 4.3, and 2.2 x 105/ml for control, 2% fat and 4%fat, respectively).

Fat source did not influence protozoa numbers in this experiment.

Grummer et al. (1993) fed sixteen multiparous Holstein cows diets containing

increasing increments of tallow. The fatty acid composition of tallow was 2.9% C14:0,

26.8% C16:0, 17.6% C18:0, 44.1% C18:1, and 4.0% C18:2. Treatments were 0, 1, 2 or

3% of dietary DM as supplemental tallow. Total mixed rations contained 33% alfalfa

silage, 12% corn silage, 14% whole roasted soybeans, and 41% concentrate based on

ground corn and soybean meal (DM basis). Tallow replaced part of the ground corn in

the fat-supplemented diets. Dietary concentration of C14:0 to C18:3 was 5.5% for

control, 6.3 for 1%, 6.9 for 2%, and 7.6 for 3% tallow diets. The dietary CP

concentration was similar among treatments. Supplementation of tallow increased fatty

acid intake of C14:0 to C18:3 linearly (1.46, 1.70, 1.80 and 1.98 kg/d for 0, 1, 2, and 3%

supplemental tallow). Ruminal fluid pH was depressed linearly by fat supplementation

(6.2, 6.1, 6.0, and 5.9 for cows fed 0, 1, 2, and 3% supplemental tallow). In situ extent of

forage DM disappearance at 48 h did not differ among treatments (forage in the insitu

bag was 73% alfalfa haylage and 27% corn silage). Ruminal fluid VFA concentrations

were increased by dietary tallow. Molar proportions of isobutyrate and isovalerate were

reduced by tallow supplementation. Butyrate concentration responded quadratically as









tallow supplementation increased. Dry matter intake, milk yield, milk fat percentage,

3.5% FCM yield, milk fat yield, and milk protein yields were unchanged by tallow

addition. Milk protein percentage decreased linearly as tallow supplementation increased

(2.89, 2.89, 2.85 and 2.86% for cows fed 0, 1, 2, and 3% supplemental tallow).

Weigel et al. (1997) evaluated how effects of tallow supplementation might be

affected by dietary concentration and source of CP. The sources of CP were soybean

meal or a by-product protein mixture containing blood meal, meat and bone meal, and

corn gluten meal. Five ruminally fistulated dairy cows were fed the following five

treatments: 1) control, 2) 15% CP, soybean meal, 3) 15% CP, by-product proteins,

4) 18% CP, soybean meal, and 5) 18% CP, soybean meal and by-product proteins. Diet 1

contained no tallow and diets 2 through 5 contained 3.5% tallow. Diets consisted of 28%

alfalfa haylage, 22% corn silage, and 50% concentrate on a DM basis. Tallow did not

affect DMI or percentages of fat and CP in milk. Dairy cows that received supplemental

tallow tended (P < 0.11) to produce more milk (31.2 vs. 28.7 kg/d) compared with the

controls. The fatty acid concentration of C6:0 through C16:0, C18:3, and glycerol in

milk fat decreased whereas the fatty acid concentration of C 17:0, C18:0, and C18:1

increased when tallow was fed. Supplemental tallow did not affect the apparent

digestibility of DM, OM, CP, ADF, NDF, or EE. The ruminal fluid pH, total VFA

concentration in ruminal fluid, or molar ratios of VFA were unchanged by tallow

supplementation. Yield of milk, milk fat, and the percentages of fat and CP in milk were

not affected by the amount or source of dietary CP. However an increase in dietary CP

from 15 to 18% increased DMI (19.8 vs. 21.5 kg/d), increased the apparent digestibility









of DM, OM, and CP, decreased ruminal fluid pH (6.03 vs. 5.97), and increased total VFA

concentration (104.2 vs. 113.0 mM).

Onetti et al. (2002) fed eighteen Holstein cows diets having different alfalfa silage:

corn silage ratios with (2%) and without (0%) tallow (DM basis). The fatty acid

composition of tallow was 3.0% C14:0, 25.1% C16:0, 19.7% C18:0, 42.1% C18:1, and

3.0% C18:2. The three dietary forage ratios were: 1) 50% corn silage, 2) 37.5% corn

silage and 12.5% alfalfa silage, and 3) 25% corn silage and 25% alfalfa silage (DM

basis). Interactions of dietary forage source and tallow were not detected. Dry matter

intake was 0.8 kg/d lower for cows fed supplemental tallow (23.3 vs. 24.1 kg/d). Tallow

supplementation increased milk production by 1.4 kg/d (37.4 vs. 36.0 kg/d). Milk fat

percentage decreased with tallow (2.9 vs. 3.2%). Milk protein production was increased

with supplemental tallow (1.22 vs. 1.18 kg/d), but milk protein percentage was

unchanged. The proportions of short and medium chain fatty acids (C4 to C14) in milk

fat decreased with supplemental tallow. The proportion of C16:0 and C18:3 in milk fat

was depressed whereas the concentration of C18:1 in milk fat was increased when tallow

was added to the diet. Tallow supplementation increased the concentration of all the

trans C18:1 isomers in milk fat except for trans-11 and trans-16 which were not affected

by tallow addition. Concentration oftrans-10, cis-12 CLA was greater in milk fat from

tallow-supplemented cows when compared with milk fat from cows that did not receive

tallow. No effect of supplemental tallow on ruminal fluid pH was observed. The molar

proportion of acetate decreased whereas that of propionate, butyrate, and valerate were

not affected when tallow was included in the diets. Molar proportions of isovalerate and

isobutyrate were increased when tallow was fed. No effect of supplemental tallow on in









situ DM and NDF disappearance was observed (data not reported). Increasing the

proportion of alfalfa silage increased DMI, milk fat percentage and milk fat yield

regardless of the fat content of the diet.

In experiment 1, Bateman et al. (1996) fed forty-eight lactating Holstein cows a

low (32.7%) or high (40.5%) NDF diet containing tallow at 0 or 0.45 kg/d during a

winter and summer season. The NDF content of the diet was manipulated by substitution

of corn and soybean meal with the fibrous by-product feeds of corn gluten feed, soyhulls,

wheat middlings, and high moisture whole ear corn. The DMI of cows fed the low NDF

diets in winter decreased when tallow was added (25.2 vs. 22.6 kg/d) but was unchanged

when tallow was added to high NDF diets. Tallow did not affect DMI during the

summer. Tallow did not influence milk production or milk fat percentage during summer

or winter. Milk protein percentage was reduced by addition of tallow during winter for

cows fed low and high NDF diets (3.30%, 3.17%, 3.22%, and 3.09% for low NDF no fat,

low NDF added fat, high NDF no fat, and high NDF added fat diets, respectively).

Inclusion of tallow in diets increased concentration of plasma NEFA during the winter

(0.19, 0.22, 016, and 0.21 mM for low NDF no fat, low NDF added fat, high NDF no fat,

and high NDF added fat diets, respectively) and summer (0.45, 0.51, 0.46, and 0.54 mM

for low NDF no fat, low NDF added fat, high NDF no fat, and high NDF added fat diets,

respectively). Concentration of plasma glucose increased with addition of tallow during

winter (74.2, 75.3, 72.5, 78.3 mg/dl for low NDF no fat, low NDF added fat, high NDF

no fat, and high NDF added fat diets, respectively) and in summer (57.5, 63.8, 57.7,and

63.4 mg/dl for low NDF no fat, low NDF added fat, high NDF no fat, and high NDF

added fat diets, respectively). Palmquist and Jenkins (1980) noted in their review that









high fat diets can result in an inability of insulin to stimulate glucose utilization by

tissues, thus causing an increase in plasma glucose concentrations.

In experiment 2, Bateman et al. (1996) fed four Holstein cows the same four diets

described above during winter to study the effects of tallow on ruminal fermentation.

Inclusion of tallow in low NDF diets decreased the proportions of acetic acid and

increased proportions of propionic acid. Addition of tallow to high fiber diets increased

acetic acid concentration and decreased propionic acid concentration. No differences in

butyric acid were observed. The A:P ratio decreased when tallow was added to low fiber

diets but increased when tallow was added to high fiber diets (tallow by NDF

interaction).

In summary, when tallow was used as a source of supplemental fat for lactating

dairy cows, DMI decreased (Ruppert et al., 2003; Onetti et al., 2001; Onetti et al., 2002)

or was unchanged (Shauff et al., 1992; Smith et al., 1993; Eastridge and Firkins, 1991;

Jenkins et al., 1998; Adams et al., 1995; Elliot et al., 1993; Wu et al., 1993; Markus et al.,

1996; Grummer et al., 1993; Weigel et al., 1997; Bateman et al., 1996; Jones et al.,

2000). The depression observed in DMI was mainly due to the unsaturated fatty acid

content in fat sources, as observed in Pantoja et al. (1994) who reported that DMI

decreased with increased degree of unsaturation of the fat source. Milk production was

not affected (Ruppert et al., 2003; Drackley and Elliot, 1993; Elliot et al., 1993; Markus

et al., 1996; Bateman et al., 1996; Jones et al., 2000), increased (Smith et al., 1993;

Eastridge and Firkins, 1991; Jenkins et al., 1998; Pantoja et al., 1996; Wu et al., 1993;

Weigel et al., 1997; Onetti et al., 2002), or decreased (Onetti et al., 2001; Grummer et al.,

1993) when tallow was supplemented to the diet. Milk fat concentration was increased









(Shauff et al., 1992), depressed (Ruppert et al., 2003; Jenkins et al., 1998; Elliot et al.,

1993; Onetti et al., 2001; Onetti et al., 2002), or unchanged (Pantoja et al., 1996; Pantoja

et al., 1994; Wu et al., 1993; Markus et al., 1996; Weigel et al., 1997; Grummer et al.,

1993; Bateman et al., 1996) by tallow addition to the diet. The composition of milk fat

was altered as tallow was supplemented to diets. Proportions of short- and medium-chain

FA in milk (C6:0 to C16:0) decreased (Ruppert et al., 2003; Shauff et al., 1992; Smith et

al., 1993; Markus et al., 1996; Onetti et al., 2001 Onetti et al., 2002) whereas long-chain

fatty acids (C16:0 to C18:2) increased (Smith et al., 1993; Markus et al., 1996; Onetti et

al., 2002) by feeding tallow. Milk protein percentage increased (Onetti et al., 2001),

decreased (Ruppert et al., 2003; Jenkins et al., 1998; Elliot et al., 1993; Pantoja et al.,

1994; Wu et al., 1993), or was not affected (Shauff et al., 1992; Eastridge and Firkins,

1991; Adams et al., 1995; Drackley and Elliot, 1993; Pantoja et al., 1996; Markus et al.,

1996; Grummer et al., 1993; Weigel et al., 1997; Onetti et al., 2002) by tallow inclusion

in the diet. Plasma glucose concentration was unchanged (Ruppert et al., 2003; Shauff et

al., 1992; Wu et al., 1993) or increased (Bateman et al., 1996) with addition of tallow

whereas plasma urea nitrogen concentration was unaffected (Shauff et al., 1992).

Ruminal fluid pH was not affected (Ruppert et al., 2003; Shauff et al., 1992; Pantoja et

al., 1994; Onetti et al., 2001; Weigel et al., 1993; Onetti et al., 2002) or decreased

(Grummer et al., 1993). Total VFA concentration was unchanged (Ruppert et al., 2003;

Markus et al., 1996; Onetti et al., 2001; Weigel et al., 1997), decreased (Elliot et al.,

1993; Pantoja et al., 1994), or increased (Grummer et al., 1993), and protozoa number per

milliliter of rumen fluid decreased (Onetti et al., 2001) with supplemental tallow. Tallow

decreased ruminal molar proportions of acetate and increased propionate (Ruppert et al.,









2003; Shauff et al., 1992; Lewis et al., 1999; Elliot et al., 1993; Onetti et al., 2001).

Others reported no effect (Pantoja et al., 1994; Markus et al., 1996). Molar proportions

of isobutyrate and isovalerate were reduced (Grummer et al., 1993) or increased (Onetti

et al., 2002) by tallow supplementation. Total tract apparent digestibilities of DM were

not affected (Ruppert et al., 2003; Lewis et al., 1999; Elliot et al., 1993; Weigel et al.,

1997), were decreased (Shauff et al., 1992; Eastridge and Firkins, 1991), or increased

(Wu et al., 1993). That of CP was decreased (Shauff et al., 1992), unchanged (Ruppert et

al., 2003; Weigel et al., 1997), or increased (Lewis et al., 1999). Total tract apparent

digestibility of ADF was not affected (Shauff et al., 1992; Lewis et al., 1999; Elliot et al.,

1993; Weigel et al., 1997) or were increased (Wu et al., 1993), whereas that of NDF was

unchanged (Shauff et al., 1992; Eastridge and Firkins, 1991; Lewis et al., 1999; Elliot et

al., 1993; Weigel et al., 1997). Total tract apparent digestibility of EE was increased

(Ruppert et al., 2003; Smith et al., 1993) or unchanged (Weigel et al., 1997) by tallow

supplementation. In situ DM digestibility of DM and NDF were decreased (Eastridge

and Firkins, 1991) by tallow.

Effects of Tallow and Fish Oil in Ruminant Diets

Jones et al. (2000) fed four midlactation Holstein cows one of four diets that

contained 3% added fat (DM basis). Diets consisted of 30% corn silage, 29% alfalfa

silage, 7.4% alfalfa hay, 30.6% corn grain and soybean meal-based concentrate, and 3%

fat (DM basis). Supplemental fat was 100% tallow, 67:33 tallow:fish oil, 50:50

tallow:fish oil, and 33:67 tallow:fish oil. The fish oil was Menhaden fish oil. Treatments

did not affect DMI, milk yield, or milk fat or protein concentration. The proportion of

fatty acids C18:0 and cis-C18:1 decreased and trans-C18:1, conjugated linoleic acid,

C18:3, C20:4, and C20:5 increased in the milk fat with increasing fish oil in the diet.









Jones et al. (1998) fed lactating Holstein cows diets containing 0% supplemental

fat, 3.2% tallow, 2.6% fish oil, or 1.9% fish oil treated with ethylamide (DM basis).

Diets consisted of 23% alfalfa silage, 20% corn silage, and 57% concentrate (DM basis).

Fish oil decreased DMI (21.0, 19.3, 16.1, and 17.1 kg/d for 0% fat, 3.2% tallow,

2.6% fish oil, and 1.9% treated fish oil, respectively). Milk and milk component yields

were decreased by all fat supplements. Fat supplements decreased proportions of milk

fatty acids C6:0 to C14:0 in milk fat, the proportions of these were greater for cows fed

fish oil than for those fed tallow. Fat supplements increased concentrations of C 16:1,

C17:0, C18:lt, CLA, and all long chain PUFA in milk fat. Compared with tallow, fish

oil increased proportions of all unsaturated fatty acids except C18:1c, which was lower.

Compared with control, fish oil decreased C18:0 and C18:lc and increased C18:lt in

milk fat.

Effects of Fish Oil in Ruminant Diets

Donovan et al. (2000) fed twelve multiparous lactating Holstein cows Menhaden

fish oil. On a DM basis, diets contained 25% corn silage, 25% alfalfa hay, and 50% of

concentrate mix. Fish oil was supplemented at 0, 1, 2, and 3% of dietary DM. Dry

matter intake showed a quadratic response, decreasing at the 2 and 3% level (28.7, 29.0,

23.5, and 20.4 kg/d for cows fed 0, 1, 2, 3% fish oil diets, respectively). Milk yield

increased for cows fed the 1% fish oil diet, but decreased thereafter with the further

addition of fish oil (31.7, 34.2, 32.3, and 27.4 kg/d for cows fed 0, 1 2, 3% fish oil diets,

respectively). The concentration of fat in milk decreased with increasing intake of fish

oil (3.0, 2.8, 2.4 and 2.3% for cows fed 0, 1, 2, 3% fish oil diets, respectively). The fatty

acid concentrations in milk fat were altered by fish oil. The proportions of short-chain

fatty acids (C4:0 to C12:0) decreased, long-chain fatty acids increased, and the milk fat









was more unsaturated. Milk protein percentages were similar among treatments. Diets

had no effect on BW change.

Cant et al. (1997) fed four primiparous Holstein cows diets of 45% orchardgrass

silage and 55% concentrate (DM basis). The four dietary treatments were a basal diet

(control), the basal diet plus 14.5 mg/kg of monensin sodium (M), 2% red fish oil (FO),

and a combination of red fish oil and monensin (FO + M). Intake of DM was reduced

when cows were fed fish oil. An interaction with monensin depressed DM intakes

further (17.5, 17.3, 15.7, 14.2 kg/d for control, M, FO, and FO + M, respectively). Milk

yield was not affected by M or FO treatments. Milk fat concentration was reduced by

feeding fish oil (3.90, 2.74, 2.53% for control, FO, and FO + M, respectively), as well as

milk fat yield (0.89, 0.57,and 0.52 kg/d). Feeding fish oil increased the concentration of

20- and 22-carbon fatty acids in milk fat.

Whitlock et al. (2002) fed eight multiparous Holstein and four multiparous Brown

Swiss cows diets containing 2% supplemental fat. The supplemental fats were menhaden

fish oil (FO) or extruded soybeans (ESB). Diets consisted of a 50:50 ratio of forage to

concentrate (DM basis). The forage sources were 25% corn silage and 25% alfalfa hay.

The concentrate was mainly cracked corn and soybean meal. In the fat-supplemented

diets, the FO replaced a portion of the cracked corn and ESB replaced a portion of the

soybean meal. The four dietary treatments were 0% supplemental fat (control diet),

2% added menhaden FO, 2% ESB, and 1% added FO plus 1% added ESB (DM basis).

Intake of DM (24.3, 21.6, 24.5, and 22.5 kg/d), milk production (32.1, 29.1, 34.6, and

31.1 kg/d), and milk fat concentration (3.51, 2.79, 3.27, and 3.14%) were lower for cows

that consumed FO, especially the 2% fish oil diet (control, FO, ESB, and FO + ESB,









respectively). Milk protein concentration was unchanged by dietary treatments.

Concentration of transvaccenic acid and cis-9, trans 11 CLA in milk fat increased with

feeding ofFO, ESB, and FO + ESB.

In experiment 1, Doreau and Chilliard (1997) used six multiparous lactating

Holstein dairy cows fitted with permanent cannulae of the rumen and proximal

duodenum. Diets consisted of 70% maize silage and 30% concentrate (DM basis). The

three treatments were no oil infusion (C), continuous ruminal infusion of 300 ml (276 g)

of menhaden fish oil (R), and a continuous duodenal infusion of 300 ml of fish oil (D).

Ruminal oil infusion decreased DM intake compared to the control cows (16.2 vs.

19.8 kg/d). The apparent digestibilities of DM (73.5 vs. 70.2%) and OM (75.5 vs.

72.6%) and NDF (64.5 vs. 59.4%) were greater for treatment R than for C. Ruminal pH

was unaffected by infusions. Ruminal oil infusion decreased the acetate proportion and

the A:P ratio and increased the propionate and isovalerate proportions. The butyrate and

valerate proportions were only decreased by the oil infusion at 1500 h. No effects on

ruminal VFA were observed with duodenal infusions.

In experiment 2, Doreau and Chilliard (1997) fed six lactating Holstein cows a

diet consisting of 65% maize silage and 35% concentrate (DM basis). The three dietary

treatments were 0 ml menhaden FO (C), 200 ml (185 g) of menhaden FO (L), and 400 ml

(370 g) of menhaden FO (H). Intake of DM was lower for treatment H than for

treatments C and L (19.2, 19.0, and 15.5 kg/d). Cows on treatment L had increased

apparent DM (69.9 vs. 66.8%) and ether extract (79.8 vs. 63.2%) digestibilities when

compared to the controls. Cows on treatment H had increased apparent DM (71.2 vs.

66.8%), OM (73.5 vs. 69.2%), NDF (52.7 vs. 47.0%), and ether extract (85.3 vs. 63.2%)









digestibilities when compared to the controls. When 400 ml of FO were added to the

diet, the proportions of acetate and acetate:propionate ratio decreased while the

proportion of propionate increased in the ruminal fluid.

Chilliard and Doreau (1997) fed eight lactating Holstein cows diets of 65% forage

and 35% concentrate (DM basis).The source of forage was maize silage. The four dietary

treatments were 1) no supplement (control), 2) 300 ml of menhaden FO, 3) 20 g of

rumen-protected methionine, and 4) 300 ml of FO plus 20 g of rumen-protected

methionine. Incorporation of FO in the diet decreased DM intake on average (19.2 vs.

17.8 kg/d for control and fish oil respectively). No differences in live weight were

detected due to treatment. Addition of FO increased milk yield by 1.6 kg/d on average

when compared to the controls (26.5 vs. 28.1 kg/d). Fish oil supplementation sharply

decreased milk fat concentration by an average by 1.3% when compared to the control

cows (3.86 vs. 2.54 %).

Keady et al. (2000) fed fifty Holstein-Friesian dairy cows grass silage and either 5

or 10 kg/d of concentrate. The dietary treatments were intakes of 0, 150, 300, or 450 g/d

of herring/markerel fish oil. Fish oil supplementation decreased DMI only at the 450 g/d

rate (16.0, 16.6, 15.7 and, 14.3 kg/d for 0, 150, 300, and 450 g/d ofFO).

Supplementation of fish oil also decreased the concentration of milk protein by 0.09% for

each 100 g increase in fish oil supplementation (3.27, 3.20, 3.01, and 2.89% for cows fed

0, 150, 300, and 450 g/d of FO). Milk fat concentration was decreased by 15% with

450 g/d of FO (4.23, 4.04, 3.66, and 2.73% for cows fed 0, 150, 300, and 450 g/d of FO).

As FO was added to the diet, milk yield increased (22.5, 25.0, 25.2, and 25.7 kg/d for

cows fed 0, 150, 300 and 450 g/d of FO). As rate of FO inclusion increased, the apparent









digestibility coefficients of DM increased (77.4, 78.5, 79.1, and 80.4 for cows fed 0, 150,

300 and 450 g/d of FO). No effect on NDF and ADF digestibility coefficients was

detected.

AbuGhazaleh et al. (2002) fed four fistulated primiparous lactating cows. Diets

consisted of 25% corn silage, 25% alfalfa hay and 50% concentrate (DM basis). Dietary

treatments were 0% supplemental fat (control diet), 2% menhaden FO, 2% added fat

from extruded soybeans (ESB), and the 1% menhaden FO and 1% added fat from ESB

(FO + ESB). Dry matter intake (23.0, 21.6, 22.7, and 21.6 kg/d for cows fed control, FO,

ESB, and FO + ESB, respectively) was reduced when diets containing FO were fed.

Milk yields were similar across all diets. Mean milk fat percentage, mean milk protein

percentage, and yield were not different among cows fed the four diets. Milk fatty acid

proportions of C6:0 to C14:0 were decreased. The concentrations of CLA cis-9, trans-11

(0.40, 0.88, 0.87 and 0.80 g/100 g of fatty acids for control, FO, ESB, and FO + ESB

diets, respectively) and transvaccenic acid (1.02, 2.34, 2.41, and 2.06 g/100 g of FA)

were increased by both fat supplements. The proportion of C18:0 FA in milk fat was not

different between control and fat-supplemented diets. Milk EPA and DHA concentration

were increased with FO supplements compared with the control and ESB diets (0.05,

0.24, 0.05, and 0.16 g of EPA /100 g of fatty acids and 0.01, 0.47, 0.02, and 0.29 g of

DHA /100 g of fatty acids for control, FO, ESB, and FO + ESB diets, respectively).

Lacasse et al. (2002) fed thirty Holstein cows in midlactation protected or

unprotected fish oil. The forage sources were grass silage and maize silage fed to the

cows in a TMR along with rolled barley. Fish oil was protected by a glutaraldehyde

microcapsule. The four dietary treatments were the following: 1) control (no









supplemented fish oil), 2) 3.7% unprotected fish oil (UFO), 3) 1.5% protected fish oil

(L-PFH), and 4) 3.0% protected fish oil (H-PFO). Cow fed unprotected fish oil had

lower feed intakes, lost more BW, and produced less milk than cows fed protected fish

oil. Concentration of milk protein and milk fat were decreased by unprotected or H-PFO.

Short and medium chain fatty acids (< C16) concentrations in milk fat were decreased by

fish oil supplementation. Concentrations ofC18:0 (6.6, 3.2, 6.1, and 4.2%) and

cis9-C18:1 (16.8, 10.6, 15.6, and 12.0%) were decreased by UFO or H-PFO for control,

UFO, L-PFO, and H-PFO, respectively. Concentrations oftrans-C18:1 were increased

by the two forms offish oil (2.9, 9.9, 6.1, and 9.7% for control, UFO, L-PFO, and

H-PFO, respectively). Concentrations of C18:2 (2.1, 3.5, 2.5, and 2.8%), C20:5 (0.04,

0.28, 0.08, and 0.17%) and C22:6 (0.08, 0.19, 0.13, and 0.15% were increased by

inclusion of UFO or H-PFO in the cow diets for control, UFO, L-PFO, and H-PFO,

respectively.

Ahnadi et al. (2002) utilized 16 Holstein cows in midlactation to examine effects of

dietary fish oil on alterations of mammary gland fatty acid metabolism. Dietary

treatments were the same as reported by Lacasse et al. 2002. Mammary gland biopsies

were taken from a rear quarter at the end of each period. Milk production was lower with

UFO supplementation when compared to cows fed control diets (27.5, 22.2, 33.9, and

30.3 kg/d for control, UFO, L-PFO, and H-PFO respectively). Milk fat percentage (3.60,

2.60, 2.40, and 2.04%) and milk fat yield (0.98, 0.55, 0.83, and 0.63 kg/d) were decreased

by fish oil addition in cows fed control, UFO, L-PFO, and H-PFO, respectively. Milk

protein percentage was lower for cows fed H-PFO (3.50, 3.26, 3.23, and 3.04% for

control, UFO, L-PFO, and H-PFO, respectively) but milk protein yield was not affected









by dietary treatments. Fish oil treatments reduced the concentrations of short and

medium chain fatty acids in milk fat. Concentrations of C16:1 in milk fat were increased

by feeding UFO and H-PFO when compared to controls (1.65, 3.88, 1.73, and 3.80% for

control, UFO, L-PFO, and H-PFO, respectively). Concentrations of C18:0 were

decreased, trans C18:1 and C20:5 were increased in milk fat of cows fed UFO and

H-PFO, and C18:2 was increased by UFO. Cows that were fed UFO had lower mRNA

abundance of acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), steroyl-CoA

desaturase (SCD), and lipoprotein lipase (LPL) enzymes and supplementation of H-PFO

resulted in a lower mRNA abundance of ACC, FAS, SCD but no effect on LPL when

compared to control diets. Concentration of plasma glucose was not affected by fish oil

supplementation.

Pate (1996) fed catfish oil in a molasses-feather meal slurry to yearling beef heifers

to observe the effects of addition of fat on body weight and pregnancy rate. The three

dietary supplements were the following: 1) molasses-urea, 2) molasses-feather meal

(13% feather meal), and 3) molasses-feather meal-catfish oil (5% fat from catfish oil).

Liquid supplements were provided in open troughs. Heifers grazed bahiagrass pastures

and were offered bales of starrgrass hay. No differences in intake were detected among

dietary treatment groups. Average daily gain and percent pregnancy were greater when

heifers were fed molasses-feather meal supplements. Percentage of pregnancy (9.5,

31.4,and 47.6% for molasses-urea, molasses-feather meal, and molasses-feather meal-

catfish oil, respectively) and average daily gain were greater when catfish oil was include

in the molasses-feather meal supplements.









In summary, fish oil supplementation resulted in a reduction in DMI (Cant et al.,

1997; Whitlock et al., 2002; Doreau and Chilliard, 1997; Chilliard and Doreau, 1997;

Keady et al., 2000; AbuGhazaleh et al., 2002; Lacasse et al., 2002). The reduction in

DMI was dependent upon the concentration of fish oil in the diet. When fish oil was

supplemented at up to 1% of dietary DM, depressions in DMI were not observed.

However when concentration of fish oil increased in the diet to > 1.6% of dietary DM,

DMI was depressed. Milk production was increased (Donovan et al., 2000; Chilliard and

Doreau, 1997; Keady et al., 2000), unchanged (Cant et al., 1997; Whitlock et al., 2002;

AbuGhazaleh et al., 2002), or decreased (Ahnadi et al., 2002; Lacasse et al., 2002) by

feeding fish oil. Milk fat concentration decreased (Donovan et al., 2000; Cant et al.,

1997; Chilliard and Doreau, 1997; Keady et al., 2000; Lacasse et al., 2002; Ahnadi et al.,

2002) or was unchanged (AbuGhazaleh et al., 2002) by fish oil addition. The fatty acid

concentrations in milk fat were altered by fish oil. Feeding fish oil caused the

proportions of short chain fatty acids (C4:0 to C12:0) to decrease (Donovan et al., 2000;

Lacasse et al., 2002; Anhadi et al., 2002; AbuGhazaleh et al., 2002), of C16:1 in milk fat

to increase (Lacasse et al., 2002), and of C18:0 to decrease (Ahnadi et al., 2002) or be

unchanged (AbuGhazaleh et al., 2002). Milk protein concentration was unchanged

(Donovan et al., 2000; Withlock et al., 2002; AbuGhazaleh et al., 2002; Ahnadi et al.,

2002) by feeding fish oil. Fish oil infusion into the rumen decreased molar proportion of

acetate (Doreau and Chilliard, 1997), increased molar proportion of propionate (Doreau

and Chilliard, 1997), and increased the apparent digestibility of DM (Doreau and

Chilliard, 1997; Keady et al., 2000), NDF (Doreau and Chilliard, 1997) and OM (Doreau

and Chilliard, 1997).














CHAPTER 3
PERFORMANCE OF LACTATING HOLSTEIN COWS FED CATFISH OIL

Introduction

Reductions in dry matter intake and milk production occur when dairy cows are

exposed to heat stress. The addition of fats to dairy cow diets during the summer period

can be an excellent choice because they are energy dense, produce less heat increment,

and do not cause the same detrimental effects as does the over feeding of starch

(Palmquist and Jenkins, 1980). Fats can be supplied from vegetable or animal sources.

The responses of the dairy cow to fat supplementation can depend on the fatty acid

profile of the fat supplement and also on the type of dietary forage (Smith et al., 1993;

Ruppert et al., 2003). Several studies reported that supplemental fat increased milk

production (Cant et al., 1991; Cant et al., 1993; DePeters et al., 1987; Martinez et al.,

1991; Donovan et al., 2000; Keady et al., 2000; Chilliard and Doreau, 1997) but also

could depress DMI. The responses were dependent partially on the fat concentration in

the dietary DM.

In the search for fat supplements to use in dairy cow diets, preliminary work in

Florida indicated that catfish oil (CFO) mixed with liquid molasses dramatically

improved intake of the liquid supplement by beef cows on rangeland (F. M. Pate,

personal communication). Catfish oil has not been evaluated as a feedstuff for dairy

cows. Because catfish are a fresh water fish, their fatty acid profile is different from that

of marine fish in that omega-3 fatty acids, eicosapentaenoic acid (EPA) and

docosahexaenoic acid (DHA), are in lower concentrations. This is due to the fact that









pond-raised fresh water fish consume less algae, the source of omega-3 fatty acids.

Feeding marine fish oil has improved milk production (Chilliard and Doreau, 1997;

Keady et al., 2000) but can decrease dry matter intake (Chilliard and Doreau, 1997;

Keady et al., 2000). If catfish oil can improve feed intake as it did with beef cows, then it

may prove to be a very effective energy supplement for increasing milk production. The

objective was to evaluate catfish oil as a dietary ingredient for lactating Holstein cows

during the summer season.

Materials and Methods

Cows and Diets

Twelve multiparous, lactating Holstein cows (six ruminally fistulated) (mean of

195 + 27 DIM) were assigned to three dietary treatments arranged in a 3 X 3 Latin square

design replicated four times. One square was composed of higher producing,

nonfistulated cows, one square was composed of lower producing, nonfistulated cows,

one square was composed of higher producing, fistulated cows, and one square was

composed of lower producing, fistulated cows. The three dietary treatments were 0, 1.5

and 3.0% catfish oil (DM basis, Protein Products, Inc., Gainesville, GA). The fatty acid

profile of the catfish oil was similar to that of tallow, containing mostly oleic and palmitic

acids (Table 3-1). Linoleic acid concentration however, was greater at 14% than is

typically reported for tallow. Catfish oil was suspended in liquid sugarcane molasses

(20% as-is basis, United States Sugar Corp., Clewiston, FL) and stored in a 6000 L

plastic tank on farm. A second tank contained molasses without catfish oil. The

respective molasses blends were mixed with concentrate ingredients in 1-ton batches and

stored on a concrete apron under cover. The concentrates were then mixed with corn

silage and alfalfa hay at the time of feeding in a weighing and mixing unit (American









Calan, Inc., Northwood, NH) and offered twice daily at 0930 and 1400 h for ad libitum

consumption allowing 10% orts.

Table 3-1. Fatty acid profile of catfish oil.

Fatty acid % of total fatty acids
C 12:0 0.10
C 14:0 1.76
C 14:1 0.13
C 16:0 18.67
C 16:1 4.93
C 18:0 5.03
C 18:1 47.04
C 18:2 14.03
C 18:3 1.16
C 20:4 0.29
C 20:5 1.13
C 22:6 3.15
Other 2.58

The experiment was conducted at the University of Florida from August to

November and consisted of three 27-d periods. The first 14 d of each period was used to

adapt cows to a new diet and the last 13 d used for data collection. Cows were housed in

a free-stall, open-sided barn fitted with Calan gates (American Calan Inc., Northwood,

NH) to allow measurement of individual feed intake. Fans and misters were operated

continuously for cooling purposes. Temperature and humidity were recorded outside and

inside the barn every 15 min throughout the experiment (Onset Computer Corporation,

Bourne, MA).

Collection of Samples and Analysis

Weights of feed offered and orts were recorded daily for each cow. Representative

samples of concentrate mixes, corn silage, and alfalfa hay were collected weekly and

composite for each experimental period. Corn silage and alfalfa hay samples were dried

at 55C in a forced-air oven and ground to pass the 1-mm screen of a Wiley mill (A.H.









Thomas, Philadelphia, PA) prior to compositing. Feedstuff samples were analyzed for

DM (1050C for 8 h), OM (5120C for 8 h), NDF (Goering and Van Soest, 1970) using

heat-stable ca-amylase, ADF (AOAC, 1990), 80% ethanol soluble carbohydrate (ESC)

(Hall et al., 1999), starch (Hall et al., 1999), Kjedahl N (AOAC, 1990) using a boric acid

modification during distillation, and ether extract (EE) (AOAC, 1990). CP was

calculated by multiplying Kjedahl N x 6.25. In addition, mineral composition was

determined by Dairy One (Ithaca, NY).

Cows were milked daily at 0500, 1300 and 2100 h and milk weights recorded.

Milk samples were collected for two consecutive milkings on d 16, 17, 23 and 24 of each

period for determination of fat, protein and SCC. Somatic cell scores were generated as

described by Norman et al. (2000) for statistical analysis of SCC. Samples were analyzed

by Southeast Dairy Labs (McDonough, GA) by infrared technologies (Bentley 2000,

Bentley Instruments, Chaska, MN). Two consecutive milk samples were collected on d

23 of each period for fatty acid analysis. These samples were stored at -200C. Milk fat

was extracted by the method of Chilliard et al. (1991). The extracted oil was placed in 15

ml Pyrex, leak-proof, Teflon-lined screw cap tubes, flushed with N, and sent to Clemson

University (Clemson, SC) on dry ice for analysis by gas chromatography (Jenkins, 2000).

Due to extended exposure of some samples to room temperature, only 24 out of 33

samples were analyzed for fatty acids.

Body weight was monitored by weighing the cows on two consecutive days at the

beginning and the end of each period before the a.m. milking. Rectal temperatures were

measured twice daily at 0430 and 1630 h on d 16, 18, 20, 22, 24 and 26 of each period.









Blood samples (-10 ml) were collected from the coccygeal vessels into Becton

Dickinson vacutainers (Becton Dickinson, Franklin Lakes, NJ) containing sodium

heparin on d 26 and 27 of each period. Blood was stored on ice for transport and

centrifuged at 3000 rpm (1916 x g) to separate plasma. Plasma was stored at -200C until

analyzed.

A Technicon Autoanalyzer (Technicon Instruments Corp., Chauncey, NY) was

used to measure plasma glucose (a modification of Gouchman and Schmitz (1972) as

described in Bran and Luebbe Industrial Method # 339-19) and blood urea nitrogen

(BUN) (a modification of Marsh et al. (1965) as described in Bran and Luebbe Industrial

Method # 339-01). Plasma insulin was analyzed using a double antibody

radioimmunoassay procedure as described by Soeldner and Sloane (1965) and modified

by Malven et al. (1987). Bound radioactivity in tubes was measured using a Packard

auto gamma counter (model B-5005). The results were calculated using the log-logit

curve fit. Sensitivity of the assay was 0.2 ng/ml and the intra-assay coefficient of

variation was 11.8%.

At 1630 h on d 23 and 24 of each period spot samples of urine were collected and

measured for pH (Horiba twin pH meter B-213, Spectrum Technologies, Inc, Plainfield,

IL). Eighty g of feces were collected, diluted in 80 ml of distilled water immediately

after collection, and measured for pH (pH meter, model 15; Fisher Scientific, Pittsburg,

PA). Urine samples were frozen at -200C and kept for analysis. In order to estimate

microbial protein synthesis, creatinine and allantoin analysis were performed as described

by Vagnoni et al. (1997).









Apparent Digestibility

Gelatin capsules containing 10 g of Cr203 were administered orally via a balling

gun twice daily at 0430 and 1630 h on d 15 to 24 of each period. Fecal grab samples

were collected before the administration of the capsules on d 20 to 24 of each period.

Fecal samples from daily collections were dried at 550C in a force-air oven and ground to

pass the 1-mm screen of a Wiley mill (A.H. Thomas, Philadelphia, PA). Samples of

dried feces were composite across sampling times to obtained one fecal sample per cow

per period. Feces were analyzed for Cr by atomic spectrophotometry (Williams et al.,

1962), DM (1050C for 8 h), OM (5120C for 8 h), NDF (Goering and Van Soest, 1970)

using heat-stable ca-amylase, ADF (AOAC, 1990), Kjedahl N (AOAC, 1990) using a

boric acid modification during distillation, and EE was determined by Dairy One (Ithaca,

NY). Apparent digestibility of DM, CP, ADF, NDF and EE were calculated by the

marker ratio technique (Schneider and Flatt, 1975).

Rate and Extent of Digestion

Rate, extent, and lag of DM and NDF digestibility of corn silage were measured on

d 25, 26, and 27 of each period by the dacron bag technique (Nocek, 1988). A single

sample of corn silage was collected at the beginning of the trial, dried at 550C for 48 h,

and ground to pass a 2-mm screen (Wiley mill, A.H. Thomas, Philadelphia, PA).

Approximately 5.5 g (as-is) was weighed into preweighed polyester bags (10 x 20 cm)

with an average pore size of 53 + 10 rtm (Bar Diamond, Inc., Parma, ID). Two single

bags were inserted into a nylon bag, attached to Nalgene bottles filled with sand and

incubated in the rumen via canula at intervals of 0, 4, 8, 12, 18, 24, 36, 48, and 72 h

starting on d 25 of each period. All bags were removed simultaneously. After removal,









bags were placed in ice water, then washed under running tap water by hand. Finally

bags were washed without soap in a washing machine on delicate/cold cycle to remove

rumen fluid. Bags were oven-dried for 48 h at 55 C, then weighed to determine DM

residue. The undigested residue was analyzed for NDF (Goering and Van Soest, 1970)

using heat-stable ca-amylase. The equation for the determination of lag time and rate of

DM and NDF digestion was the same as used in the study by Mertens and Ely (1982):

R= Doe-K(t-L)+ U when t > L and R= Do + U when 0 < t < L

where

R = DM or NDF residue at time t after incubation,

Do = slowly digestible fraction at t < L and Do = R U,

K = digestion rate constant,

L = discrete lag time, and

U = indigestible fraction at 72 h of in situ fermentation.

Digestion rate constants and discrete lag times were calculated with the nonlinear

models procedure of SAS using Marqardt's method (1996).

Sampling and Analysis of Ruminal Fluid

Ruminal fluid was collected hourly for 8 h starting at feeding on d 15 of each

period using the ruminally fistulated cows. The pH was measured immediately upon

collection (pH meter, model 15; Fisher Scientific, Pittsburg, PA). A subsample of about

30 ml was acidified with 50% sulfuric acid to a pH between 2 and 3 and centrifuged at

5400 x g for 20 min. The supernatant was collected and frozen immediately at -200C

until further analysis for VFA on a 4% carbomax 80/120 BDA (Supelco Inc., Bellefonte,

PA) column in a gas chromatograph (Autosystem XL, Perkin Elmer Inc., Norwalk CT).









Prior to injection unto column, samples were centrifuged at 5000 x g for 30 min and

filtered with a high affinity protein syringe-driven filter unit (Millex SLAA025LS,

Fisher Scientific, Pittsburg, PA). The gas chromatograph was set to a flow rate of 30

ml/min of N, an injection port temperature of 2000C, oven at 1750C, and the flame

ionizing detector at 4500C.

Protozoa numbers were determined as described by Dehority (1984). Ten ml of

ruminal fluid that were collected every two hours for 8 h starting at feeding were mixed

with 10 ml of 50% formaline and stored at room temperature until further analysis. Two

drops of brilliant green dye were added to 1 mm aliquots of preserved ruminal fluid and

allowed to stand overnight. After staining, 9 ml of 30% glycerol were added and Iml of

the diluted sample was pippeted into a Sedgewick-Rafter counting chamber (1-cm3

volume). Protozoa were counted at a magnification of 100X. The goal was to have

approximately 100 to 150 protozoa per 50 grids. Further dilutions were made with 30%

glycerol if needed.

Statistical Analysis

Measurements of feed intake, milk production and composition, in situ lag, rate,

and extent of digestion, apparent digestibility, pH of urine and feces, rectal temperatures,

plasma glucose, plasma urea nitrogen, and microbial protein synthesis were analyzed by

the general linear procedure (GLM) of SAS (1996).

The model was

Yijkl = | + ai + + i k + k + (a)il +(ay)ik + gikl

Yijkl = response variable in square i in period k in treatment 1 for cow j,

[t = overall mean,









ai = effect of square i,

ij = effect of cow j within square i,

y= effect of period k,

S= effect of treatment 1,

(ac)il = effect of interaction of square i with treatment 1,

(ay)ik = effect of interaction of square i with period k, and

Sijkl = residual effect of i, j, k, and 1.

Results are reported as least squares means. Significance was determined at P <

0.05 and a tendency toward significance at P < 0.12. The fatty acid profile of milk

samples were analyzed as an incomplete Latin square design due to missing values. The

model was the same as above except that square, square by treatment interaction, and

square by period interaction were deleted. Repeated measures of ruminal pH, protozoa

numbers, and VFA data were analyzed by the mixed procedure of SAS (1996).

Covariance structures were tested to determine the best fit for each dependent variable.

Single degree of freedom contrasts for linear and quadratic effects of treatment were

tested. Two squares were designed as containing higher-producing cows and two squares

were designed as containing lower-producing cows. The error term for square was cow

within square. A reduced model was used pooling the square by period interaction with

the error term if the square by period interaction was P > 0.25. Secondly, if the treatment

by square interaction was P > 0.25, it was pooled with the error term, as well (Bancroft,

1968).









Results and Discussion

Diet Composition.

As the proportion of CFO increased in the diet, the proportion of whole cottonseed

decreased whereas that of soybean meal increased (Table 3-2). Diets contained similar

concentrations of CP, starch, sugar, and minerals but concentration of dietary fiber

decreased whereas that of EE increased with increasing concentration of CFO.

Intake Response and Apparent Digestibility.

Dry matter intake (kg/d and as a % of BW) increased linearly with increasing

intake of CFO (Table 3-3). DePeters et al. (1987) also reported an increase in DMI when

cows were fed diets of 3.5 and 7% yellow grease compared to those fed diets without

yellow grease. Others have reported increased DMI as more saturated fats replaced

unsaturated fats. As partially hydrogenated tallow replaced tallow, DMI increased from

23.1 to 24.7 kg/d (Pantoja et al., 1996). In agreement was the work ofPantoja et al.

(1994) in which DMI increased as partially hydrogenated tallow replaced tallow which in

turn replaced a tallow-canola oil mixture (20.8, 18.8, and 17.8 kg/d). The fatty acid

profile of CFO contains less polyunsaturated fatty acids than whole cottonseeds (WCS).

The fatty acid profile of WCS is 0.8% C14:0, 22.7% C16:0, 0.8% C16:1, 2.3% C18:0,

17.0% C18:1, 51.5% C18:2, and 0.2% C18:3 (Coppock and Wilks, 1991). When marine

fish oils were a source of supplemental fat, DMI was depressed when the fish oil

constituted > 1.6% of dietary DM (Jones et al., 1998; Donovan et al., 2000; Cant et al.,

1997; Whitlock et al., 2002; Doreau and Chilliard, 1997; Chilliard and Doreau, 1997;

Keady et al., 2000; AbuGhazaleh et al., 2002; Lacasse et al., 2002) but was unchanged

when fed at < 1% of dietary DM (Donovan et al., 2000; Keady et al., 2000). Most studies

have reported no effect on DMI by feeding yellow grease ((Martinez et al., 1991; Cant et









al., 1991; Nianogo et al., 1991; Avila et al., 2000; Oldick et al., 1997) or tallow (Shauff et

al., 1992; Smith et al., 1993; Eastridge and Firkins, 1991; Jenkins et al., 1998, Adams et

al., 1995; Drackley and Elliot, 1993; Wu et al., 1993, Grummer et al., 1993; Markus et

al., 1996; Weigel et al., 1997; Bateman et al., 1996) but others have reported a depression

in DMI when tallow was fed at 2% of dietary DM (Onetti et al., 2001, 2002; Ruppert et

al., 2003). The mechanisms by which supplemental fat sometimes depresses feed intake

are not clear but could involve effects of fat on ruminal fermentation and gut motility,

acceptability of diets containing added fat, release of gut hormones, and oxidation of fat

in the liver (Allen, 2000).

Accompanying the increase in DMI, apparent digestibility of DM increased linearly

as intake of CFO increased (Table 3-3). Similar to this study, apparent digestibility of

DM increased when cows were fed yellow grease (Jenkins and Jenny, 1989; Nianogo et

al., 1991) or marine fish oil (Doreau and Chilliard, 1997; Keady et al., 2000). Part of this

increase in DM digestibility in the present study was due to an increased digestibility of

the EE fraction of the diet; that is, the EE in CFO was more digestible than that in whole

cottonseeds and the other ingredients. The nonnutritive fraction of EE is known to be of

lower digestibility than the fatty acid fraction of EE. Others have reported a greater

apparent EE digestibility when cows were fed marine fish oil (Doreau and Chilliard,

1997), yellow grease (DePeters et al., 1987), or tallow (Ruppert et al., 2003; Smith et al.,

1993).

The apparent digestibility of CP also was increased linearly as intake of CFO

increased (Table 3-3). Soybean meal increased in the diet along with increasing

concentration of CFO. Therefore this increase in extent of CP digestion may have









occurred simply because the protein in soybean meal was more digestible than that in

whole cottonseed. (NRC, 2001). Alternatively replacing whole cottonseed oil with CFO

may have relieved an inhibitory effect of cottonseed oil on ruminal microbes thus

improving ruminal digestion of dietary CP. However others have reported an

improvement in apparent CP digestibility when lactating dairy cows were fed yellow

grease (Nianogo et al., 1991) or tallow (Lewis et al., 1999) and the fat sources replaced

grains.

Apparent digestibilities of NDF and ADF were increased linearly as intake of CFO

increased (Table 3-3). Likewise Doreau and Chilliard (1997) reported an increase in

NDF digestibility when marine fish oil was supplemented at 370 g/d. These findings are

in contrast to other reports of supplemental fat depressing fiber digestibility (Cant et al.,

1991; Nianogo et al., 1991; Oldick et al., 1997; Smith et al., 1993). It has been suggested

often that the negative effect of dietary lipids on intake is mainly due to a depressive

effect on ruminal digestion or to a low palatability of fat supplements. It was not the case

in this study in which CFO enhanced both DMI and digestibility. The extent that fat may

interfere with digestion depends on the amount fed and the source. Increasing

esterification or saturation of fats generally lessens its negative effects on ruminal

fermentation (Palmquist and Jenkins, 1980). Feeding CFO had a similar effect on

digestibility by higher- and lower-producing cows.

Cows were gaining > 0.9 kg/d (Table 3-3). No difference was detected in BW gain

when cows were fed CFO, however cows fed CFO had numerically greater BW gain than

cows fed the control diet. DePeters et al. (1987) reported greater BW gain by cows in

late compared to early lactation when fed yellow grease.









Morning rectal temperatures increased linearly as cows were fed increasing

amounts of CFO whereas afternoon rectal temperatures tended to increase quadratically

(Table 3-3). These increases were most likely due to increased DMI of cows fed CFO.

In situ Dry Matter and Neutral Detergent Fiber Digestion.

In situ lag, rate and extent of digestion of corn silage DM was unchanged by

feeding CFO (Table 3-4). Greater milk producers had 3 h less lag time for DM digestion

than lower producers.

In situ lag time of NDF digestion was unchanged by CFO, but the rate of NDF

digestion increased linearly with increasing amounts of CFO in the diet (0.023, 0.024,

and 0.029 h-1). However the extent of NDF digestion at 72 h was similar across diets

(average 63.4%). Increased rate of NDF digestion likely contributed to the increase in

apparent total tract digestion ofNDF observed in cows fed CFO (Table 3-3). Yang

(2002) reported that NDF digestibilities were increased by 15% with addition of

branched-chain VFA to the media. However the molar proportion of branched-chain

VFA in the present study were not increased by feeding CFO.

Unsaturated fatty acids can cause an alteration in the rumen ecosystem due to the

suppression of methanogenic (and to a lesser extent cellulolytic) bacteria and protozoa

(Van Soest, 1994). A decrease in methane production results in an alteration of the

rumen fermentation leading to an increase in propionate production to maintain the

rumen fermentation balance. The possible depression of methane producers in the rumen

and no change in protozoa numbers by CFO inclusion in this study may have created a

space in the microbial mass that cellulolytic bacteria occupied thus increasing fiber

digestion.









Milk Production and Composition.

Milk production (Table 3-5) was unchanged by CFO in the diet. This is surprising

since cows fed CFO consumed increasing amounts of digestible DM (Table 3-3).

Donovan et al. (2000) reported that milk yield increased for cows fed 1% marine fish oil

diets, but milk yield decreased when fish oil was fed at 3% of dietary DM. Keady et al.

(2000) also reported an increase in milk yield when marine fish oil was fed at 0.9, 1.9 and

3.1% of dietary DM using diets high in grass silage. However others reported a reduction

in milk production when feeding diets of 3.7% fish oil (Lacasse et al., 2002) or 2% fish

oil (Whitlock et al., 2002).

Milk fat concentration was unchanged by CFO, averaging 3.55% (Table 3-5). The

milk fat response to ruminally available supplemental fat may differ depending on the

source of forage. Smith et al. (1993) reported that milk fat percentage tended to be

depressed when tallow was added to diets containing only corn silage (3.33 vs. 3.15%)

but tended to be increased when tallow was added to diets containing both corn silage

and alfalfa hay (3.27 vs. 3.58%) (tallow by corn silage vs. alfalfa hay interaction, P <

0.08). Ruppert et al. (2002) reported that milk fat percentage tended (P < 0.06) to

decrease linearly as dietary tallow supplementation to corn silage-based diets increased

(3.18, 2.89, and 2.70% for 0, 2, and 4% tallow diets, respectively) whereas it was

unchanged when supplemented to alfalfa silage-based diets (3.39, 3.44, and 3.41% for 0,

2, and 4% tallow diets, respectively) (forage source by tallow interaction). This may be

attributed to the higher content of non-FA lipid in EE from alfalfa silage compared with

corn silage. In studies reporting milk fat depression due to fat supplementation (Onetti et

al., 2002; Martinez et al., 1991), the depression was probably by inhibition on acetyl-CoA

carboxylase by increased concentrations of long chain acyl CoA in the mammary gland









(Palmquist and Jenkins, 1980). In this study, production of milk fat and 4% FCM were

not affected by CFO supplementation.

Milk protein percentage, milk protein yield, and somatic cell counts were

unchanged by the inclusion of CFO in the diets. In agreement are others who have

reported no effect of supplemental tallow or yellow grease on milk protein percentage

(Avila et al., 2000; Martinez et al., 1991; Onetti et al., 2002).

Fatty Acid Composition of Milk Fat.

Short- and medium-chain fatty acids, C4:0 to C12:0 in milk fat, were not affected

by inclusion of CFO in the diet (Table 3-6). The supply of long chain fatty acids to the

mammary gland was not changed appreciably by replacing whole cottonseed with CFO.

Therefore it is not unexpected that concentrations of C4 to C12 fatty acids were similar

across diets. Concentration of C14:0 tended (P = 0.08) to increase linearly in milk fat of

cows fed increasing amounts of CFO. The concentrations of fatty acids C14:1 and C16:1

increased linearly in milk fat of cows fed increasing amounts of CFO. Concentration of

C18:0 in milk fat decreased linearly with inclusion of CFO in the diet. The concentration

of C18:2 tended (P = 0.07) to decrease by increasing amounts of CFO in the milk fat,

whereas increasing concentration of C20:5 due to CFO supplementation came close to

significance (P = 0.11). These effects were likely due to the differences in fatty acid

profiles between CFO and WCS. Whole cottonseeds oil contains greater concentrations

of 18-carbon fatty acids. Fiber digestibility was not depressed in this study, thus having

no effect on the availability of acetate for de novo synthesis of fatty acids in the

mammary gland (Eastridge and Firkins, 1991). Concentrations of cis-9, trans 11 C18:2

and trans-10, cis-12 C18:2 increased numerically with increasing intake of CFO but large

standard errors prevented these response from being significant. Others (AbuGhazaleh et









al., 2002; Whitlock et al., 2002) have reported that the feeding of marine fish oil

increased the conjugated linoleic acid concentration of milk fat. A lack of response in the

current study was likely due to a lower concentration of EPA and DHA in CFO compared

to that in marine fish oil (Whitlock et al., 2002).

Ruminal Fermentation.

Diet by hour interactions were not observed for any of the ruminal measurements.

Ruminal fluid pH decreased linearly when cows were fed diets of increasing

concentration of CFO (6.41, 6.20, and 6.15 for 0, 1.5, 3.0% CFO, respectively; Table

3-7). This lower pH may have resulted from greater intake and digestibility of DM of

diets with increasing concentration of CFO (Table 3-3). Lower producing cows

experienced a sharp drop in ruminal pH when CFO was increased in the diet but higher

producing cows had the highest ruminal pH when fed the 1.5% CFO diet (Figure 3-1;

quadratic effect of diet by square interaction). Grummer et al. (1993) observed a linear

reduction in ruminal pH with increasing concentrations of tallow in the diet (0, 1, 2, and

3%) Authors indicated that this reduction reflected a stimulation rather than an inhibition

of fermentation as DMI was unchanged by tallow supplementation.

Total VFA concentrations in ruminal fluid were similar across diets. This is

somewhat surprising since ruminal fluid pH decreased linearly as intake of CFO

increased. The VFA are absorbed from the rumen at a faster rate with decreasing pH.

Therefore increased production of VFA accompanied by increased absorption of VFA

may have resulted in no net change in VFA concentration of cows fed CFO compared to

controls. In high producing cows molar proportion of acetate in ruminal fluid decreased

linearly with increasing concentrations of CFO in the diet (65.1, 64.0, and 63.0 molar %

for cows fed 0, 1.5, and 3.0% CFO diets, respectively) whereas that of lower producing









cows was unchanged (Figure 3-2; linear effect of diet by square interaction). Molar

proportion of propionate increased linearly by adding CFO in the diet (19.4, 20.0, and

20.4 molar%/ for 0, 1.5, 3.0% CFO). As a result, the acetate to propionate ratio in ruminal

fluid decreased linearly as more CFO was fed to cows. Doreau and Chilliard (1997)

reported a decrease in molar proportion of acetate and an increase in propionate in

ruminal fluid of cows fed diets supplemented with 370 g/d menhaden fish oil. Similarly

results were obtained by Onetti et al. (2001), Elliot et al. (1993), Lewis et al. (1999), and

Shauff et al. (1992) when tallow was the source of fat. Molar proportions of butyrate

tended to increase with CFO (12.2, 12.4, 12.5 molar %, for 0, 1.5, 3.0% CFO,

respectively). This response was more evident in high producing cows (Figure 3-3; linear

effect of diet by square interaction). Molar proportions of isobutyrate, 2-methylbutyrate,

valerate, and isovalerate decreased in ruminal fluid of cows fed 1.5% CFO but then

increased when cows were fed diets of 3% CFO (quadratic effect of diet). The response

pattern of the branch chained fatty acids due to feeding CFO of lower producing cows

showed a greater depression at the 1.5% CFO diet that did higher producing cows

(Figures 3-4, 3-5, and 3-6; diet by square interactions). As reported by Doreau and

Chilliard (1996), the modification of the VFA profile suggests a change in the ruminal

microbial ecosystem. The changes in the present study were not negative since an

improvement in rate of NDF digestion and total tract apparent digestibility was improved.

Onetti et al. (2001) reported a decrease in protozoa number per milliliter of rumen

fluid as tallow or choice white grease increased in the diet from 0 to 4% of dietary DM.

Their study reported no difference in protozoa numbers between sources of fat. In the

current study, protozoa numbers in ruminal fluid were decreased in cows fed 1.5% CFO









diets in lower producing cows whereas, in higher producing cows, the protozoa numbers

were greater when cows were fed the 1.5% CFO diet (Figure 3-7; quadratic effect of diet

by square interaction).

Microbial protein yield (g/d) increased in cows fed diets of 1.5% CFO but returned

to that of controls when cows were fed diets of 3.0% CFO (quadratic effect). This may

have contributed to the improvement in diet digestibility (Table 3-3) and rate of NDF

digestion (Table 3-4).

Urine pH from higher producing cows increased linearly whereas that of lower

producing cows decreased linearly with increasing dietary concentration of CFO (Figure

3-8; linear effect of diet by square interaction). Feeding CFO at 1.5% of dietary DM

resulted in elevated fecal pH from lower milk producers but lower fecal pH from high

milk producers (Figure 3-9; quadratic effect of diet by square interaction).

Blood Metabolites.

Plasma urea, glucose, or insulin were not affected by CFO supplementation (Table

3-8). Other studies have reported no change in plasma glucose concentration when fat

was added to the diet (Ruppert et al., 2003; Shauff et al., 1992; Wu et al., 1993; Ahnadi et

al., 2002). Bateman et al. (1996) observed an increase in plasma glucose with addition of

tallow at 0.45 kg/d. Palmquist and Jenkins (1980) noted in their review that high fat diets

can result in an inability of insulin to stimulate glucose utilization by tissues, thus causing

an increase in plasma glucose concentration. A decrease in plasma glucose concentration

with increased concentration of yellow grease in the diets was reported by Avila et al.

(2000) and Cant et al. (1993). Similar to this study, Smith et al. (1993), Ruppert et al.

(2003), and Shauff et al. (1992) reported no effect of fat supplementation on blood urea

nitrogen concentration.






64


Summary

Catfish oil mixed with liquid molasses and fed to lactating Holstein cows at 1.5 and

3% of dietary dry matter stimulated dry matter intake and digestibility. Fermentation in

the rumen was not affected negatively by feeding CFO based upon improved in situ

digestion rate of NDF, lack of appreciable change in VFA, and improved synthesis of

microbial protein. Although the production and composition of milk was unchanged by

feeding CFO in this study, the improvement in feed intake and digestibility hold promise

that milk production could be improved in future work.











Table 3-2. Ingredient and chemical composition of experimental diets containing catfish
oil (CFO) fed to lactating Holstein cows in summer.
DIET
Ingredient 0% CFO 1.5% CFO 3.0% CFO
Corn silage, % of DM 29.9 29.9 29.9
Alfalfa hay, % of DM 11.5 11.5 11.5
Cottonseed hulls, % of DM 4.7 4.7 4.7
Corn meal, % of DM 17.2 17.2 17.0
Soybean meal, % of DM 11.5 13.0 14.4
Citrus pulp, % of DM 5.6 5.6 5.6
Whole cottonseed, % of DM 5.2 2.6 0
Prolak, % ofDM1 1.5 1.5 1.5
Liquid molasses, % of DM 2 8.1 4.0 0
Liquid molasses + CFO, % of DM 3 0 5.3 10.5
Mineral mix, % of DM 4 4.4 4.4 4.4
Biophos, % of DM 5 0.3 0.3 0.5

Chemical
CP, % of DM 18.3 18.3 18.5
NDF, % of DM 30.3 30.9 28.5
ADF, % of DM 18.9 18.7 17.1
Ether extract, % of DM 4.75 5.33 5.59
Starch, % of DM 23.1 23.3 24.1
Sugars, % of DM 9.3 8.7 9.3
Ca, % of DM 1.31 1.35 1.34
P, % of DM 0.47 0.47 0.49
Mg, % ofDM 0.38 0.40 0.44
K, % of DM 1.79 1.77 2.10
Na, % of DM 0.51 0.49 0.50
S, % of DM 0.34 0.34 0.32
Cu, ppm of DM 32 32 29
Fe, ppm of DM 244 250 260
Mn, ppm of DM 104 110 108
Zn, ppm of DM 99 122 119
SH. J. Baker & Bro., Inc., Stanford, CT.
2 United States Sugar Corp., Clewiston, FL.
3 CFO supplied by Protein Products, Inc., Gainesville, GA to United States Sugar Corp.
(Clewiston, FL) for mixing at 20.0% (as-is basis).
4 Mineral and vitamin mix contained 26.4% CP, 1.74% fat, 10.15% Ca, 0.90% P, 3.1%
Mg, 8.6% Na, 5.1% K, 1.5% S, 4.1% Cl, 2231 mg/kg of Mn, 1698 mg/kg of Zn, 339
mg/kg Fe, 512 mg/kg of Cu, 31 mg/kg of Co, 26 mg/kg of I, 7.9 mg/kg of Se, 67,021
IU/kg of vitamin A, 19,845 IU/kg of vitamin D, and 357 IU/kg of vitamin E (DM basis).
5 IMC-Agrico, Bannockburn, IL.














Table 3-3. Dry matter intake (DMI), apparent digestibility coeficients ofDM, CP, NDF, ADF and ether extract (EE), body weight
change, and rectal temperatures (RT) of lactating Holstein cows fed catfish oil (CFO) in summer.

Square Diet Square Diet x square interaction
Linear x Quadratic x
CFO in dietary DM Linear Quadratic HM vs. LM HM vs. LM HM vs. LM
Higher milk Lower milk SE
producers producers
Measure 0% 1.5% 3.0% (HM) (LM) ----------------------------P value------- ----------------
DMI, kg/d 23.0 24.4 25.4 26.0 22.6 0.6 0.01 0.81 0.001 1' 1
DMI, % ofBW 3.2 3.4 3.5 3.7 3.1 0.08 0.03 0.94 0.001 0.21 0.92

Apparent digestibility, %
DM 69.9 74.5 75.3 74.2 72.3 0.81 0.001 0.08 0.07 0.31 0.68
CP 72.2 75.8 76.2 75.4 74.1 0.96 0.01 0.19 0.27 0.91 0.70
NDF 51.9 59.0 58.5 57.7 55.2 1.72 0.02 0.10 0.23 0.65 0.94
ADF 41.5 50.4 49.0 50.0 43.9 2.05 0.02 0.06 0.02 0.56 0.84
EE 91.5 93.7 94.4 93.5 92.9 0.3 0.004 0.06 0.07 0.40 0.87

Body weight change,
kg/27 days 25.3 35.0 31.0 31.0 30.0 6.3 0.55 0.42 0.89 0.35 0.34


RT at 0430 h, C 38.2 38.2 38.4 38.3 38.3 0.04 0.03 0.13 1.0 0.09 0.98
RT at 1630 h, C 38.7 38.8 38.7 38.8 38.7 0.04 0.99 0.08 0.09
SP values were not generated due to use of reduced model.














Table 3-4. In situ lag, rate, and extent of DM and NDF digestion of corn silage by lactating Holstein cows fed catfish oil (CFO) in
summer.

Square Diet Square Diet x square interaction
Linear x Quadratic x
CFO in dietary DM Linear Quadratic HM vs. LM HM vs. LM HM vs. LM
Higher milk Lower SE
producers milk
(HM) producers
Measure 0% 1.5% 3.0% (LM) ---------------------------------P value----------------------------------
DM
Lag, h 2.1 1.8 4.9 1.4 4.4 0.8 0.08 0.17 0.035 0.10 0.65
Rate, h' 0.022 0.022 0.029 0.023 0.026 0.002 0.12 0.40 0.47 0.22 0.81
72 extent, % 83.7 81.7 83.2 81.7 84.1 1.4 0.85 0.43 0.26 0.57 0.70

NDF
Lag, h 9.7 8.8 10.8 8.4 11.0 1.5 0.82 0.73 0.49 0.96 0.54
Rate, h' 0.023 0.024 0.029 0.024 0.026 0.001 0.04 0.24 0.28 0.11 0.86
72 h extent, % 65.5 60.4 64.3 60.4 66.3 3.2 0.83 0.38 0.23 0.55 0.68



Table 3-5. Milk production and composition of lactating Holstein cows fed catfish oil (CFO) in summer.

Square Diet Square Diet x square interaction
Linear x Quadratic x
CFO in dietary DM Linear Quadratic HM vs. LM HM vs. LM HM vs. LM
Higher milk Lower milk SE
producers producers
Measure 0% 1.5% 3.0% (HM) (LM) -----------------------------------P value-----------------------------------
Milk, kg/d 29.0 29.0 29.5 34.5 23.8 0.5 0.52 0.72 0.001 0.81 0.61
Milk fat, % 3.57 3.60 3.48 3.48 3.62 0.14 0.70 0.71 0.40 0.84 0.46
Milk fat, kg/d 1.03 1.02 1.01 1.18 0.86 0.05 0.81 0.99 0.001 0.70 0.72
Milk protein, % 3.21 3.18 3.23 3.10 3.32 0.02 0.48 0.27 0.001 0.67 0.19
Milk protein, kg/d 0.91 0.91 0.94 1.06 0.78 0.02 0.39 0.54 0.001 0.69 0.34
4% FCM, kg/d 27.0 27.0 27.0 31.5 22.5 0.8 0.96 0.94 0.001 0.77 0.66
SCC x 1000/ml 154 95 109 176 130 0.5 0.51 0.49 0.14 0.80 0.81











Table 3-6. Fatty acid composition of milk fat of lactating Holstein cows fed catfish oil
(CFO) in summer.

Diets
CFO in dietary DM Linear Quadratic
Measure 0% 1.5% 3.0% SE ------------P values----------
%
Fatty acids
C4:0 3.51 3.52 3.36 0.11 0.32 0.59
C6:0 2.37 2.49 2.41 0.06 0.62 0.27
C8:0 1.28 1.38 1.36 0.05 0.28 0.45
C10:0 2.88 3.13 3.10 0.15 0.31 0.51
C11:0 0.03 0.05 0.04 0.01 0.37 0.47
C12:0 3.22 3.55 3.61 0.19 0.16 0.61
C14:0 10.32 11.21 11.38 0.39 0.08 0.51
C14:1 1.28 1.51 1.63 0.07 0.004 0.52
C15:0 0.82 0.94 0.93 0.05 0.13 0.31
C16:0 29.05 28.93 30.04 0.56 0.22 0.43
C16:1 1.43 1.59 1.84 0.08 0.004 0.68
C17:0 0.48 0.47 0.46 0.02 0.23 0.89
C18:0 10.31 9.10 7.89 0.62 0.02 0.99
C18:1 20.93 19.27 19.46 0.80 0.21 0.41
trans-C18:1 1.57 2.15 1.83 0.27 0.48 0.25
C18:2 3.32 3.05 3.07 0.09 0.07 0.27
C18:3 0.33 0.32 0.35 0.02 0.44 0.50
cis-9, trans-11 CLA 0.008 0.009 0.011 0.005 0.62 0.98
trans-9, cisll CLA 0.05 0.05 0.05 0.004 0.71 0.81
trans-10, cisl2 CLA 0.004 0.009 0.010 0.005 0.40 0.73
C20:0 0.18 0.19 0.18 0.01 0.94 0.75
C21:0 0.06 0.06 0.07 0.003 0.10 0.46
C22:0 0.19 0.19 0.18 0.01 0.20 0.51
C22:1 0.20 0.19 0.20 0.01 0.96 0.31
C20:5 0.02 0.02 0.03 0.005 0.11 0.38
C24:0 0.02 0.03 0.02 0.007 0.66 0.39
C22:6 0.02 0.04 0.03 0.03 0.84 0.70














Table 3-7.Volatile fatty acid concentration, pH, microbial protein production, and protozoa numbers in ruminal fluid and pH of urine
and feces of lactating Holstein cows fed catfish oil (CFO) in summer.

Square Diet Square Diet x square interaction
Linear x Quadratic x
CFO in dietary DM Linear Quadratic HM vs. LM HM vs. LM HM vs. LM
Higher milk Lower milk SE
producers producers
Measure 0% 1.5% 3.0% (HM) (LM) ---------------------------P value---------------------------------
Ruminal fluid pH 6.41 6.20 6.15 6.16 6.34 0.07 0.001 0.12 0.23 0.001 0.001
Acetate, molar % 64.5 64.2 63.4 64.0 64.0 0.77 0.02 0.58 0.99 0.02 0.51
Propionate, molar % 19.4 20.0 20.4 20.2 19.7 0.53 0.02 0.78 0.62 0.40 0.78
Butyrate, molar % 12.2 12.4 12.5 12.1 12.6 0.43 0.08 0.37 0.59 0.05 0.93
Isobutyrate, molar % 0.77 0.62 0.68 0.68 0.70 0.04 0.006 0.001 0.80 0.001 0.03
2-Methylbutyrate, molar% 1.30 1.08 1.17 1.06 1.31 0.08 0.04 0.003 0.20 0.02 0.41
Valerate, molar % 1.32 1.26 1.37 1.48 1.16 0.09 0.43 0.07 0.16 0.79 0.95
Isovalerate, molar % 0.51 0.38 0.44 0.41 0.47 0.04 0.01 0.001 0.48 0.02 0.01
Total VFA, mM 109.1 112.6 111.9 119.0 103.4 12.0 0.69 0.73 0.54 0.15 0.23
Acetate:Propionate 3.38 3.22 3.18 3.23 3.30 0.13 0.01 0.35 0.81 0.06 0.89

Microbial protein, g/d 298 342 285 303 313 11 0.42 0.016 0.47 0.55 0.77
Protozoa, x105/ml 7.6 7.1 7.7 7.0 7.9 0.6 0.86 0.23 0.39 0.29 0.009
Urine pH 8.05 8.05 8.06 8.06 8.04 0.02 0.92 0.80 0.30 0.03 0.67
Fecal pH 6.69 6.71 6.68 6.66 6.72 0.02 0.83 0.38 0.02 0.69 0.03

Table 3-8. Concentrations of plasma urea, glucose and insulin of lactating Holstein cows fed catfish oil (CFO) in summer.

Square Diet Square Diet x square interaction
Linear x Quadratic x
CFO in dietary DM Linear Quadratic HM vs. LM HM vs. LM HM vs. LM
Higher milk Lower milk SE
producers producers
Measure 0% 1.5% 3.0% (HM) (LM) ---------------------------------.P value--------------------------------------
Plasma urea, mg/dl 11.6 11.0 12.0 11.5 11.5 0.4 0.61 0.20 0.89 0.86 0.25
Plasma glucose, mg/dl 57.8 55.1 56.0 55.6 57.0 1.1 0.30 0.24 0.33 0.96 0.42
Plasma insulin, ng/ml 0.55 0.53 0.57 0.51 0.58 0.04 0.74 0.56 0.17 0.55 0.14


















6.6


S6.4


6.2
.3

S6.0


5.8


5.6


5.4


Low Producers


S0 % CFO
E 1.5 % CFO
0 3 %CFO


High Producers


Figure 3-1. Ruminal fluid pH for low milk producers and high milk producers fed 0, 1.5,
and 3.0% catfish oil (CFO). Quadratic effect of diet by square interaction, P
0.001.

67.0


65.0


S64.0


S63.0


, 62.0


61.0


60.0


59.0


* 0%CFO
I 1.5 % CFO
03 % CFO


Low Producers High Producers


Figure 3-2. Molar proportion of acetate in ruminal fluid for low milk producers and high
milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Linear effect of diet by
square interaction, P = 0.02.



















12.5


S12.0
5

11.5


11.0


10.5


10.0


Low Producers


* 0%CFO
R 1.5 % CFO
03 % CFO


High Producers


Figure 3-3. Molar proportion of butyrate in ruminal fluid for low milk producers and
high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Linear effect of
diet by square interaction, P = 0.05.

1.0


. 0.6
o

0.5






0.2

0.1

0.0
0.


S0% CFO
F 1.5 % CFO
03 % CFO


Low Producers High Producers


Figure 3-4. Molar proportion ofisobutyrate in ruminal fluid for low milk producers and
high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Quadratic effect
of diet by square interaction, P = 0.03.

















1.4


1.2


j 1.0

0.8


S0.6

0.4


0.2

0.0


* 0% CFO
0 1.5 % CFO
03 % CFO


Low Producers High Producers


Figure 3-5. Molar proportion of 2-methylbutyrate in ruminal fluid for low milk
producers and high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO).
Linear effect of diet by square interaction, P = 0.02.

0.7


0.6


0.5


o 0.4






0.2


0.1


0.0
0.0 --


* 0%CFO
E 1.5 % CFO
03 % CFO


Low Producers High Producers


Figure 3-6. Molar proportion of isovalerate in ruminal fluid for low milk producers and
high milk producers fed 0, 1.5, and 3.0% catfish oil (CFO). Quadratic effect
of diet by square interaction, P = 0.01.
































2-



0 -


S0 % CFO
S1.5 % CFO
S3 % CFO


Low Producers High Producers


Figure 3-7. Protozoa numbers in ruminal fluid for low milk producers and high milk
producers fed 0, 1.5, 3.0% catfish oil (CFO). Quadratic effect of diet by
square interaction, P = 0.009.

8.2 ,


8.1


a 8.05


S 8


7.95


7.9


7.85


0 % CFO
S1.5 % CFO
S3 % CFO


Low Producers High Producers


Figure 3-8. Urine pH for low milk producers and high milk producers fed 0, 1.5, and
3.0% catfish oil (CFO). Linear effect of diet by square interaction, P = 0.03.















6.8


6.75


6.7


m 6.65


6.6


6.55


6.5


6.45


S0% CFO
0 1.5 % CFO
03 % CFO


Low Producers High Producers


Figure 3-9. Fecal pH for low milk producers and high milk producers fed 0, 1.5, and
3.0% catfish oil (CFO). Quadratic effect of diet by square interaction, P
0.03.
















APPENDIX
TEMPERATURE AND RELATIVE HUMIDITY

Table A-1. Average temperature (Temp), relative humidity (RH), and temperature
humidity index (THI) in 6-h increments on collection days measured within
the free stall barn at the Dairy Research Unit at Hague, Florida.'


Period Date Time Frame, h
1 9-4-01 0000- 0559
1 9-4-01 0600- 1159
1 9-4-01 1200- 1759
1 9-4-01 1800- 2359
1 9-5-01 0000- 0559
1 9-5-01 0600- 1159
1 9-5-01 1200- 1759
1 9-5-01 1800- 2359
1 9-6-01 0000- 0559
1 9-6-01 0600- 1159
1 9-6-01 1200- 1759
1 9-6-01 1800- 2359
1 9-7-01 0000- 0559
1 9-7-01 0600- 1159
1 9-7-01 1200- 1759
1 9-7-01 1800- 2359
1 9-8-01 0000- 0559
1 9-8-01 0600- 1159
1 9-8-01 1200- 1759
1 9-8-01 1800- 2359
1 9-9-01 0000- 0559
1 9-9-01 0600- 1159
1 9-9-01 1200- 1759
1 9-9-01 1800- 2359
1 9-10-01 0000- 0559
1 9-10-01 0600- 1159
1 9-10-01 1200- 1759
1 9-10-01 1800- 2359
1 9-11-01 0000- 0559
1 9-11-01 0600- 1159
1 9-11-01 1200- 1759
1 9-11-01 1800- 2359
1 9-12-01 0000- 0559


Temp, 0
23.15
24.58
30.43
25.43
23.12
24.30
31.61
24.55
23.15
24.42
28.90
23.97
22.54
23.86
30.43
24.93
22.22
23.44
29.39
26.43
23.39
24.32
29.07
26.02
23.51
24.35
28.29
26.12
23.24
25.10
28.63
24.38
22.80


C


RH, %
92.85
89.00
65.65
84.46
92.51
89.03
59.71
90.39
95.20
92.68
74.23
91.52
94.66
91.66
61.44
87.54
95.35
94.33
68.96
80.34
93.58
89.97
70.03
86.67
93.88
90.66
76.30
84.85
94.14
89.04
73.36
90.27
93.43


THI2
73.5
75.6
81.8
76.5
73.4
75.1
82.5
75.7
73.7
75.7
80.8
74.8
72.6
74.6
81.1
76.0
72.0
74.1
80.7
77.7
74.0
75.2
80.4
77.8
74.2
75.3
80.1
77.7
73.8
76.5
80.2
75.4
72.9











Period Date Time Frame, h


9-12-01
9-12-01
9-12-01
9-13-01
9-13-01
9-13-01
9-13-01
9-14-01
9-14-01
9-14-01
9-14-01
9-15-01
9-15-01
9-15-01
9-15-01
9-16-01
9-16-01
9-16-01
9-16-01
10-1-01
10-1-01
10-1-01
10-1-01
10-2-01
10-2-01
10-2-01
10-2-01
10-3-01
10-3-01
10-3-01
10-3-01
10-4-01
10-4-01
10-4-01
10-4-01
10-5-01
10-5-01
10-5-01
10-5-01
10-6-01
10-6-01
10-6-01
10-6-01
10-7-01


0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000


1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559


Temp, C
23.89
26.90
22.90
22.09
22.35
23.37
20.98
21.05
21.12
21.84
21.17
20.68
19.22
22.78
20.82
18.08
17.57
25.87
22.91
13.32
14.55
22.24
17.63
11.85
14.44
24.18
19.93
14.61
15.66
25.84
21.58
17.08
19.29
27.16
22.93
20.49
21.90
28.82
24.07
22.35
24.70
29.40
25.20
22.41


RH, %
90.98
78.51
93.40
95.97
94.39
89.84
94.28
94.96
96.20
95.41
96.28
96.02
89.88
72.63
78.84
75.62
79.54
57.46
74.55
87.88
74.36
37.99
65.80
88.23
79.08
42.41
71.49
88.76
85.70
47.52
74.32
91.11
84.96
51.93
73.85
82.03
80.60
54.20
78.65
90.45
88.75
66.48
81.53
93.70


THI2
74.6
78.2
73.1
71.9
72.2
73.6
69.8
70.0
70.2
71.4
70.3
69.4
66.5
71.1
68.5
64.0
63.4
74.2
71.5
56.4
58.5
67.6
63.0
53.9
58.3
70.3
66.7
58.6
60.4
73.0
69.4
62.9
66.4
75.2
71.5
68.2
70.4
77.8
73.7
71.9
75.7
80.4
75.8
72.3


Table A-1.


Continued











Period Date Time Frame,h


10-7-01
10-7-01
10-7-01
10-8-01
10-8-01
10-8-01
10-8-01
10-9-01
10-9-01
10-9-01
10-9-01
10-10-01
10-10-01
10-10-01
10-10-01
10-11-01
10-11-01
10-11-01
10-11-01
10-12-01
10-12-01
10-12-01
10-12-01
10-13-01
10-13-01
10-13-01
10-13-01
10-28-01
10-28-01
10-28-01
10-28-01
10-29-01
10-29-01
10-29-01
10-29-01
10-30-01
10-30-01
10-30-01
10-30-01
10-31-01
10-31-01
10-31-01
10-31-01
11-1-01


0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000


1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559


Temp, C
20.60
21.38
19.01
16.73
18.41
24.25
20.44
18.15
19.41
25.08
21.65
18.07
19.10
24.56
22.64
20.21
21.43
26.91
22.42
19.73
21.45
27.03
23.60
21.33
22.44
27.83
24.53
7.11
7.52
16.50
12.50
9.28
10.82
19.95
15.39
10.53
11.85
22.85
18.01
13.48
15.44
23.79
21.00
18.83


RH,%
89.85
78.28
80.72
83.29
79.95
67.93
82.25
92.82
85.09
58.38
73.33
89.95
86.65
73.04
79.22
90.75
86.54
59.06
78.83
91.78
86.02
64.48
82.33
89.96
87.02
63.49
80.86
60.39
63.99
46.82
69.07
69.78
68.47
59.64
76.38
78.98
75.95
50.81
74.26
91.35
91.31
66.45
79.09
90.66


THI2
68.9
69.4
65.7
62.1
64.7
72.9
68.1
64.8
66.6
73.1
69.5
64.5
66.1
73.9
71.5
68.2
70.0
75.8
71.1
67.5
70.0
76.6
73.3
70.1
71.8
77.7
74.7
48.0
48.3
61.0
55.4
50.5
52.9
66.1
59.8
52.1
54.3
69.4
63.9
56.7
60.0
72.1
68.8
65.9


Table A-1.


Continued











Period Date Time Frame, h


Temp, C


3 11-1-01 0600- 1159 19.49
3 11-1-01 1200- 1759 26.15
3 11-1-01 1800- 2359 21.94
3 11-2-01 0000- 0559 19.25
3 11-2-01 0600- 1159 21.16
3 11-2-01 1200- 1759 26.47
3 11-2-01 1800- 2359 23.18
3 11-3-02 0000- 0559 20.49
3 11-3-01 0600- 1159 20.71
3 11-3-01 1200- 1759 26.72
3 11-3-01 1800- 2359 22.04
3 11-4-01 0000- 0559 19.60
3 11-4-01 0600- 1159 20.87
3 11-4-01 1200- 1759 24.22
3 11-4-01 1800- 2359 20.65
3 11-5-01 0000- 0559 18.82
3 11-5-02 0600- 1159 17.52
3 11-5-01 1200- 1759 19.49
3 11-5-01 1800- 2359 15.47
3 11-6-01 0000- 0559 9.98
3 11-6-01 0600- 1159 11.24
3 11-6-01 1200- 1759 21.12
3 11-6-01 1800- 2359 14.90
3 11-7-01 0000- 0559 7.42
3 11-7-01 0600- 1159 9.28
3 11-7-01 1200- 1759 21.92
3 11-7-01 1800- 2359 15.03
3 11-8-01 0000- 0559 10.16
3 11-8-01 0600- 1159 13.28
3 11-8-01 1200- 1759 23.55
3 11-8-01 1800- 2359 17.92
3 11-9-01 0000- 0559 12.01
3 11-9-01 0600- 1159 13.28
3 11-9-01 1200- 1759 24.05
3 11-9-01 1800- 2359 17.60
Measures taken every 15 minutes.
2 Temperature-Humidity Index: (0.81 x dry bulb temperature in
humidity/100) x (dry bulb temperature 14.4)) + 46.6.


C) + ((relative


Continued


RH, %
88.03
59.82
79.93
92.81
91.43
68.58
80.85
92.95
92.09
68.38
84.40
94.67
91.73
74.45
83.78
86.08
79.84
51.72
68.82
85.46
77.33
43.72
68.61
89.23
82.98
31.96
67.98
87.17
84.77
44.45
70.94
88.20
84.14
44.19
68.43


THI2
66.9
74.8
70.4
66.7
69.9
76.3
72.5
68.9
69.2
76.7
70.9
67.4
69.4
73.5
68.6
65.6
63.3
65.0
59.9
50.9
53.3
66.7
59.0
46.4
49.9
66.8
59.2
51.1
56.4
69.7
63.6
54.2
56.4
70.3
63.0


Table A-1.










Table A-2. Average temperature (Temp),relative humidity (RH), and temperature
humidity index (THI) on 6-h increments on collection days measured outside
the free stall barn at the Dairy Research Unit at Hague, Florida.1


Period Date Time Frame, h
1 9-4-01 0000- 0559
1 9-4-01 0600- 1159
1 9-4-01 1200- 1759
1 9-4-01 1800- 2359
1 9-5-01 0000- 0559
1 9-5-01 0600- 1159
1 9-5-01 1200- 1759
1 9-5-01 1800- 2359
1 9-6-01 0000- 0559
1 9-6-01 0600- 1159
1 9-6-01 1200- 1759
1 9-6-01 1800- 2359
1 9-7-01 0000- 0559
1 9-7-01 0600- 1159
1 9-7-01 1200- 1759
1 9-7-01 1800- 2359
1 9-8-01 0000- 0559
1 9-8-01 0600- 1159
1 9-8-01 1200- 1759
1 9-8-01 1800- 2359
1 9-9-01 0000- 0559
1 9-9-01 0600- 1159
1 9-9-01 1200- 1759
1 9-9-01 1800- 2359
1 9-10-01 0000- 0559
1 9-10-01 0600- 1159
1 9-10-01 1200- 1759
1 9-10-01 1800- 2359
1 9-11-01 0000- 0559
1 9-11-01 0600- 1159
1 9-11-01 1200- 1759
1 9-11-01 1800- 2359
1 9-12-01 0000- 0559
1 9-12-01 0600- 1159
1 9-12-01 1200- 1759
1 9-12-01 1800- 2359
1 9-13-01 0000- 0559
1 9-13-01 0600- 1159
1 9-13-01 1200- 1759
1 9-13-01 1800- 2359
1 9-14-01 0000- 0559
1 9-14-01 0600- 1159


Temp, 0
22.78
24.84
31.25
25.08
22.67
24.52
32.52
23.87
22.73
24.64
29.20
23.40
22.09
24.11
31.29
24.14
21.77
23.48
30.07
25.98
22.97
24.13
29.71
25.38
23.28
24.37
28.46
25.54
22.81
25.58
28.77
23.93
22.36
24.07
27.20
22.49
21.93
22.17
23.21
20.76
20.89
21.09


C


RH, %
94.25
87.47
61.43
85.45
95.03
88.05
55.58
93.51
97.33
92.25
73.04
94.29
96.93
90.38
57.54
91.02
97.66
94.50
64.68
82.09
96.12
90.72
67.39
89.45
96.19
90.24
74.84
87.01
96.47
87.10
71.40
92.41
95.29
90.03
76.78
94.36
96.93
95.01
90.18
95.21
95.56
96.58


THIL
72.9
75.8
82.3
76.0
72.8
75.4
83.0
74.8
73.1
76.0
81.1
74.0
72.0
74.9
81.7
75.0
71.4
74.2
81.1
77.1
73.4
75.0
81.0
77.0
74.0
75.3
80.2
77.0
73.2
77.1
80.2
74.8
72.3
74.8
78.5
72.5
71.7
71.9
73.3
69.5
69.7
70.1











Period Date Time Frame, h


9-14-01
9-14-01
9-15-01
9-15-01
9-15-01
9-15-01
9-16-01
9-16-01
9-16-01
9-16-01
10-1-01
10-1-01
10-1-01
10-1-01
10-2-01
10-2-01
10-2-01
10-2-01
10-3-01
10-3-01
10-3-01
10-3-01
10-4-01
10-4-01
10-4-01
10-4-01
10-5-01
10-5-01
10-5-01
10-5-01
10-6-01
10-6-01
10-6-01
10-6-01
10-7-01
10-7-01
10-7-01
10-7-01
10-8-01
10-8-01
10-8-01
10-8-01
10-9-01
10-9-01


1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600


1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159


Temp, C
21.90
21.19
20.63
19.23
23.34
20.51
17.62
17.73
27.67
22.50
11.49
14.47
23.15
16.66
10.06
14.98
25.84
19.72
13.52
16.33
27.32
21.53
16.55
19.84
28.37
23.07
20.24
21.86
29.52
23.99
22.09
24.59
29.50
24.75
21.96
20.22
21.36
18.65
16.21
18.59
24.77
19.95
17.55
19.70


RH, %
95.22
96.05
96.29
89.75
70.04
80.50
77.28
79.30
51.91
76.41
94.30
74.36
33.74
67.20
93.44
77.29
35.65
71.42
92.19
84.49
40.51
74.76
95.47
83.65
45.53
72.60
83.80
80.18
48.08
78.91
91.87
89.06
64.94
82.53
95.88
91.33
77.36
82.04
85.88
79.32
64.85
84.75
96.45
83.92


THI2
71.5
70.3
69.3
66.5
71.8
68.1
63.4
63.6
75.9
71.0
53.2
58.4
68.3
61.6
50.7
59.2
71.6
66.4
56.7
61.4
74.0
69.4
62.1
67.2
75.9
71.6
67.9
70.3
77.8
73.6
71.6
75.6
80.3
75.2
71.6
68.3
69.3
65.2
61.3
65.0
73.4
67.5
63.9
67.0


Table A-2.


Continued











Period Date Time Frame, h


10-9-01
10-9-01
10-10-01
10-10-01
10-10-01
10-10-01
10-11-01
10-11-01
10-11-01
10-11-01
10-12-01
10-12-01
10-12-01
10-12-01
10-13-01
10-13-01
10-13-01
10-13-01
10-28-01
10-28-01
10-28-01
10-28-01
10-29-01
10-29-01
10-29-01
10-29-01
10-30-01
10-30-01
10-30-01
10-30-01
10-31-01
10-31-01
10-31-01
10-31-01
11-1-01
11-1-01
11-1-01
11-1-01
11-2-01
11-2-01
11-2-01
11-2-01
11-3-02
11-3-01


1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600
1200
1800
0000
0600


1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159


Temp, C
25.89
21.40
17.27
19.44
24.86
22.72
20.00
21.74
27.72
22.32
19.25
21.58
27.27
23.61
21.20
22.55
28.06
24.51
5.66
7.50
16.74
11.47
8.83
10.98
20.70
14.75
9.84
12.26
23.77
17.22
12.79
15.40
24.26
20.52
18.31
19.80
26.67
21.33
18.60
21.32
27.06
22.96
20.03
20.72


RH, %
53.74
74.15
94.37
85.49
70.59
79.28
92.40
84.67
53.58
79.25
94.17
85.25
60.53
82.33
91.44
86.85
59.59
80.82
66.79
63.90
42.13
73.02
71.98
67.78
53.87
78.79
82.31
73.49
46.07
77.63
95.88
91.63
62.86
81.22
93.52
86.68
56.06
82.96
96.60
91.12
64.39
81.94
95.46
91.96


THI2
73.7
69.1
63.3
66.6
74.1
71.6
68.0
70.4
76.2
71.0
66.8
70.2
76.5
73.3
70.0
71.9
77.5
74.6
45.3
48.3
61.1
53.7
49.7
53.2
66.8
58.8
50.8
55.0
70.2
62.7
55.4
60.0
72.4
68.2
65.1
67.3
75.1
69.6
65.7
70.2
76.7
72.2
68.2
69.2


Table A-2.


Continued











Period Date Time Frame, h


3 11-3-01 1200
3 11-3-01 1800
3 11-4-01 0000
3 11-4-01 0600
3 11-4-01 1200
3 11-4-01 1800
3 11-5-01 0000
3 11-5-02 0600
3 11-5-01 1200
3 11-5-01 1800
3 11-6-01 0000
3 11-6-01 0600
3 11-6-01 1200
3 11-6-01 1800
3 11-7-01 0000
3 11-7-01 0600
3 11-7-01 1200
3 11-7-01 1800
3 11-8-01 0000
3 11-8-01 0600
3 11-8-01 1200
3 11-8-01 1800
3 11-9-01 0000
3 11-9-01 0600
3 11-9-01 1200
3 11-9-01 1800
1Measure taken every 15 minutes.
2 Temperature-Humidity Index: (0.81


1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359
0559
1159
1759
2359


Temp, C
27.26
21.57
18.93
20.95
24.32
20.27
18.57
17.20
19.30
13.61
7.74
11.13
21.63
13.52
6.09
9.53
23.21
14.08
8.83
13.54
25.04
16.92
10.40
13.38
25.53
16.64


x dry bulb temperature in C) + ((relative


humidity/100) x (dry bulb temperature 14.4)) + 46.6.


RH, %
64.53
86.59
98.37
91.48
73.24
85.81
87.48
81.23
50.86
76.83
93.43
77.93
39.00
73.43
95.02
81.23
25.97
71.20
91.99
83.40
38.89
74.81
93.84
84.40
37.72
70.76


THI2
77.0
70.3
66.4
69.6
73.6
68.0
65.3
62.8
64.7
57.0
46.7
53.1
66.9
56.9
43.6
50.4
67.7
57.8
48.6
56.9
71.0
62.2
51.3
56.6
71.5
61.7


Table A-2.


Continued










Table A-3. Average temperature (Temp), relative humidity (RH), and temperature
humidity index (THI) by period on collection days measured within the free
stall barn at the Dairy Research Unit at Hague, Florida.
Temp, C RH, % THI
Period MIN MAX Mean MIN MAX Mean MIN MAX Mean
1 21.21 28.80 24.15 69.92 92.91 85.82 70.18 79.75 74.33
2 16.39 27.11 21.35 57.79 90.20 77.38 61.66 75.81 68.98
3 11.81 24.09 17.34 55.28 86.85 74.29 54.12 71.43 62.65


Table A-4. Average temperature (Temp), relative humidity (RH), and temperature
humidity index (THI) by period on collection days measured outside the free
stall barn at the Dairy Research Unit at Hague, Florida.
Temp, C RH, % THI
Period MIN MAX Mean MIN MAX Mean MIN MAX Mean
1 20.75 29.80 24.11 64.94 95.39 85.97 69.48 80.39 74.20
2 15.65 27.69 21.34 52.35 93.60 77.04 60.39 75.85 68.79
3 10.72 24.69 17.09 49.78 91.91 74.99 52.06 71.67 62.09


"MIN
- MAX


1 2 3 4 5 6 7 8 9
DAY OF COLLECTION


10 11 12 13


Figure A-1. Minimum (MIN) and maximum (MAX) temperature humidity index (THI)
recorded inside the free stall barn during each day of collection averaged
across the three experimental periods. Average time of minimum THI was
0844 h. Average time of maximum THI was 1543 h.


---~---


































5 6 7 8 9
DAY OF COLLECTION


10 11 12 13


Figure A-2.


Minimum (MIN) and maximum (MAX) temperature humidity index (THI)
recorded inside the free stall barn during each day of collection of
experimental period 1. Average time of minimum THI was 0814 h.
Average time of maximum THI was 1552 h.


MIN
AMAX


nfl n -


4 5 6 7 8 9 10
DAY OF COLLECTION


11 12 13


Figure A-3. Minimum (MIN) and maximum (MAX) temperature humidity index (THI)
recorded inside the free stall barn during each day of collection of
experimental period 2. Average time of minimum THI was 0820 h.
Average time of maximum THI was 1459 h.


-U- MIN
-- MAX


1 2



































Figure A-4.


-U-MIN
|MAX


10 11 12 13


Minimum (MIN) and maximum (MAX) temperature humidity index (THI)
recorded inside the free stall barn during each day of collection of
experimental period 3. Average time of minimum THI was 0937 h.
Average time of maximum THI was 1618 h.


--MIN
-AMAX


1 2 3 4 5 6 7 8 9
DAY OF COLLECTION


10 11 12 13


Figure A-5. Minimum (MIN) and maximun (MAX) temperature humidity index (THI)
recorded outside the free stall barn during each day of collection averaged
across the three experimental periods. Average time of minimum THI was
0828 h. Average time of maximum THI was 1459 h.


1 2 3 4 5 6 7 8 9
DAY OF COLLECTION


...........



































Figure A-6.


--MIN
--MAX


10 11 12 13


Minimum (MIN) and maximun (MAX) temperature humidity index (THI)
recorded outside the free stall barn during each day of collection of
experimental period 1. Average time of minimum THI was 0751 h.
Average time of maximum THI was 1449 h.


--MIN
-rMAX


1 2 3 4 5 6 7 8 9 10 11 12 13
DAY OF COLLECTION


Figure A-7.


Minimum (MIN) and maximun (MAX) temperature humidity index (THI)
recorded outside the free stall barn during each day of collection of
experimental period 2. Average time of minimum THI was 0826 h.
Average time of maximum THI was 1453 h.


1 2 3 4 5 6 7 8 9
DAY OF COLLECTION







87


Figure A-8.


---MIN
"hMAX


1 2 3 4 5 6 7 8 9 10 11 12 13
DAY OF COLLECTION

Minimum (MIN) and maximun (MAX) temperature humidity index (THI)
recorded outside the free stall barn during each day of collection of
experimental period 3. Average time of minimum THI was 0905 h.
Average time of maximum THI was 1514 h.


- 0% CFO
-- 1.5% CFO
--3.0% CFO


0 1 2 3 4 5 6 7 8
Hour after feeding


Figure A-9.


Hourly measurements of ruminal fluid pH of cows fed diets containing 0,
1.5, or 3.0% catfish oil (CFO) after feeding. Hour designated with an *
indicated treatment differences at P < 0.05 whereas those with a t indicates
treatment differences at P < 0.10
















LITERATURE CITED


AbuGhazaleh, A. A., D. J. Schingoethe, A. R. Hippen, K. F. Kalscheur, and L. A.
Whitlock. 2002. Fatty acid profiles of milk and rumen digesta from cows fed fish
oil, extruded soybeans or their blend. J. Dairy Sci. 85:2266-2276.

Adams, A. L., B. Harris, Jr., H. H. Van Horn, and C. J. Wilcox. 1995. Effects of varying
forage types on milk production responses to whole cottonseed, tallow, and yeast.
J. Dairy Sci. 78:573-581.

Ahnadi, C. E., N. Beswick, L. Delbecchi, J. J. Kennelly, and P. Lacasse. 2002. Addition
offish oil to diets for dairy cows. II. Effects on milk fat and gene expression of
mammary lipogenic enzymes. J. Dairy Res. 69:521-531.

Allen, M. S. 2000. Effects of diet on short-term regulation of feed intake by lactating
dairy cattle. J. Dairy Sci. 83:1598-1624.

Association of Official Analytical Chemists, International. 1990. Official Methods of
Analysis. 15th ed. AOAC, Arlington, VA.

Avila, C. D., E. J. DePeters, H. Perez-Monti, S. J. Taylor, and R. A. Zinn. 2000.
Influences of saturation ratio of supplemental dietary fat on digestion and milk
yield in dairy cows. J. Dairy Sci. 83:1505-1519.

Bancroft, T. A. 1968. Page 8 in Topics in Intermediate Statistics. Iowa State Univ.
Press, Ames, IA.

Bateman, H. G., J. N. Spain, and M. R. Ellersieck. 1996. Influence of by-product feeds
and tallow on lactation performance of Holstein cows during two seasons. J. Dairy
Sci. 79:114-120.

Bauchart, D. 1993. Lipid absorption and transport in ruminants. J. Dairy Sci. 76:3864-
3881.

Bauchart, D., F. Legay-Carmier, M. Doreau, and B. Gaillard. 1990. Lipid metabolism of
liquid-associated and solid-adherent bacteria in rumen contents of dairy cows
offered lipid-supplemented diets. Brit. J. Nut. 63:563-578.

Cant, J. P., E. J. DePeters, and R. L. Baldwin. 1991. Effect of dietary fat and
postruminal casein administration on milk composition of lactating dairy cows. J.
Dairy Sci. 74:211-219.