NutrientRequirementsof Dairy CattleSeventh Revised Edition, 2001

Subcommittee on Dairy Cattle NutritionCommittee on Animal NutritionBoard on Agriculture and Natural ResourcesNational Research Council

NATIONAL ACADEMY PRESSWashington, D.C.

NATIONAL ACADEMY PRESS 2101 Constitution Avenue, NW Washington, D.C. 20418

NOTICE: The project that is the subject of this report was approved by the Governing Board of the NationalResearch Council, whose members are drawn from the councils of the National Academy of Sciences, the NationalAcademy of Engineering, and the Institute of Medicine. The members of the committee responsible for the reportwere chosen for their special competences and with regard for appropriate balance.

This study was supported by the Agricultural Research Service of the U.S. Department of Agriculture underAgreement No. 59-32U4-5-6, the Center for Veterinary Medicine of the U.S. Department of Health and HumanServices under Agreement No. R-13-FD01495, and the American Feed Industry Association.

Library of Congress Cataloging-in-Publication Data

Nutrient requirements of dairy cattle / Subcommittee on Dairy CattleNutrition, Committee on Animal Nutrition, Board on Agriculture, NationalResearch Council. 7th rev. ed.

p. cm.Includes bibliographical references (p. ).ISBN 0-309-06997-11. Dairy cattleNutritionRequirements. 2. Dairy cattleFeeding

and feeds. I. National Research Council (U.S.). Subcommittee on DairyCattle Nutrition.

SF203 .N883 2001636.213dc21 00-012828

Additional copies of this report are available from the National Academy Press, 2101 Constitution Avenue, N.W.,Lockbox 285, Washington, D.C. 20055; (800) 624-6242 or (202) 334-3313 (in the Washington metropolitan area);Internet, http://www.nap.edu.

Copyright 2001 by the National Academy of Sciences. All rights reserved.

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The National Academy of Engineering was established in 1964, under the charter of the National Academyof Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in theselection of its members, sharing with the National Academy of Sciences the responsibility for advising the federalgovernment. The National Academy of Engineering also sponsors engineering programs aimed at meeting nationalneeds, encourages education and research, and recognizes the superior achievements of engineers. Dr. WilliamA. Wulf is president of the National Academy of Engineering.

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The National Research Council was organized by the National Academy of Sciences in 1916 to associate thebroad community of science and technology with the Academys purposes of furthering knowledge and advisingthe federal government. Functioning in accordance with general policies determined by the Academy, the Councilhas become the principal operating agency of both the National Academy of Sciences and the National Academyof Engineering in providing services to the government, the public, and the scientific and engineering communities.The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts andDr. William A. Wulf are chairman and vice chairman, respectively, of the National Research Council.

iii

SUBCOMMITTEE ON DAIRY CATTLE NUTRITION

JIMMY H. CLARK, Chair, University of IllinoisDAVID K. BEEDE, Michigan State UniversityRICHARD A. ERDMAN, University of MarylandJESSE P. GOFF, USDA/ARS/NSDC, Ames, IowaRIC R. GRUMMER, University of WisconsinJAMES G. LINN, University of MinnesotaALICE N. PELL, Cornell UniversityCHARLES G. SCHWAB, University of New HampshireTREVOR TOMKINS, Milk Specialties CompanyGABRIELLA A. VARGA, Pennsylvania State UniversityWILLIAM P. WEISS, The Ohio State University

COMMITTEE ON ANIMAL NUTRITION

GARY L. CROMWELL, Chair, University of KentuckyMARY E. ALLEN, National Zoological ParkMICHAEL L. GALYEAN, Texas Tech UniversityRONALD W. HARDY, University of IdahoBRIAN W. McBRIDE, University of GuelphKEITH E. RINEHART, Perdue Farms Inc.L. LEE SOUTHERN, Louisiana State UniversityJERRY W. SPEARS, North Carolina State UniversityDONALD R. TOPLIFF, West Texas A&M UniversityWILLIAM P. WEISS, The Ohio State University

Staff

CHARLOTTE KIRK BAER, Program DirectorNORMAN GROSSBLATT, EditorSTEPHANIE PADGHAM, Project AssistantMELINDA SIMONS, Project Assistant*

* through January 1999

v

BOARD ON AGRICULTURE AND NATURAL RESOURCES

HARLEY W. MOON, Chair, Iowa State UniversityDAVID H. BAKER, University of IllinoisMAY R. BERENBAUM, University of IllinoisCORNELIA B. FLORA, Iowa State UniversityROBERT T. FRALEY, Monsanto Company, St. Louis, MissouriROBERT B. FRIDLEY, University of California, DavisW.R. (REG) GOMES, University of CaliforniaPERRY R. HAGENSTEIN, Institute for Forest Analysis, Planning, and Policy, Wayland,

MassachusettsGEORGE R. HALLBERG, The Cadmus Group, Inc., Waltham, MassachusettsCALESTOUS JUMA, Harvard UniversityGILBERT A. LEVEILLE, McNeil Consumer Healthcare, Denville, New JerseyWHITNEY MACMILLAN, Cargill, Inc., Minneapolis, Minnesota (retired)WILLIAM L. OGREN, U.S. Department of Agriculture (retired)NANCY J. RACHMAN, Novigen Sciences, Inc., Washington, District of ColumbiaG. EDWARD SCHUH, University of MinnesotaJOHN W. SUTTIE, University of WisconsinTHOMAS N. URBAN, Pioneer Hi-Bred International, Inc., Des Moines, Iowa (retired)ROBERT P. WILSON, Mississippi State UniversityJAMES J. ZUICHES, Washington State University

Staff

WARREN MUIR, Executive DirectorDAVID L. MEEKER, DirectorCHARLOTTE KIRK BAER, Associate DirectorSHIRLEY B. THATCHER, Administrative Assistant

vi

Preface

Dairy cattle production is an important component ofthe food industry. Nutrition is a key factor in the perfor-mance, health, and welfare of dairy cattle. Given the largevariation in dairy cattle types and the various environmentsin which they are maintained, producers must increasinglyconcern themselves with optimizing feeding programs.

To that end, the Subcommittee on Dairy Cattle Nutri-tion, which was appointed in 1997 under the guidanceof the Committee on Animal Nutrition in the NationalResearch Councils Board on Agriculture and NaturalResources, embarked on a monumental task in the devel-opment of a new edition of Nutrient Requirements of DairyCattle. As we conducted our work, it was our desire toprovide users of this volume an accurate, comprehensive,and useful review of the scientific literature and practicalexperiences that have shaped our knowledge of dairy cattlenutrition over the past decade.

We chose to provide both a written description of thebiologic basis for predicting nutrient requirements and acomputer model on a compact disk to use for estimatingrequirements of lactating, nonlactating, growing, andyoung dairy animals. The subcommittee recognizes thatsome users of this revision will prefer to apply tables ofrequirements for an average situation, and we haveattempted to provide those tables. Although there is oftenuncertainty using a modeling approach to estimate nutrient

vii

requirements, we believed that we had a responsibility tomove the science forward, so we included a model thatwas constructed on a substantial amount of data. Webelieve that the model builds on the work of previousResearch Council committees and moves the science for-ward without reaching so far that estimates cannot be vali-dated. We found that an abundance of new science-basedknowledge had surfaced since the last edition, but we alsofound that our knowledge of many aspects of dairy cattlenutrition is incomplete; we chose not to venture too farfrom what our knowledge base would allow.

In developing this report, the subcommittee consideredcurrent issues in dairy cattle production inasmuch as theyaffect nutrient requirements and animal feeding manage-ment, including new emphasis on environmental consider-ations in the feeding of dairy cattle. We have attemptedin this new edition to focus more than in the past onconsiderations and criteria for establishing nutrientrequirements.

This study was conducted through the concerted effortsof the members of the Subcommittee on Dairy CattleNutrition. We began our 3-year task in 1997 and completedthis volume in 2000. We hope that it will be used with thesame passion and enthusiasm with which it was developed.

JIMMY H. CLARK, ChairSubcommittee on Dairy Cattle Nutrition

Acknowledgments

A volume of this magnitude represents the combinedefforts of many individuals. The subcommittee thanks allthose who shared their insights and knowledge to bringthis document to fruition. We would first like to thankeveryone who participated in our public sessions and thespecial sessions that were organized for our benefit duringthe American Dairy Science Association meetings over thepast several years.

During the course of its deliberations, the subcommitteesought advice and special assistance from several peoplewho gave generously of their time to help us complete ourtask. Very special thanks are due to Carl Davis, Universityof Illinois; Jim Drackley, University of Illinois; Gale Bate-man, University of Illinois; Danny Fox, Cornell University;Brian Garthwaite, Food and Drug Administration; andNormand St. Pierre, Ohio State University. We areextremely indebted to them. In addition, we sought andreceived guidance early on from R. Lee Baldwin, Univer-sity of California, Davis; Mark Hanigan, Purina Mills, Inc.;Rick Kohn, University of Maryland; and Dale Waldo,U. S. Department of Agriculture (retired).

The expertise of Vajesh Durbal, Cornell University, isgratefully acknowledged. He was instrumental in program-ming the computer model, and we could not have accom-plished what we did without his skill and patience.

The subcommittee is grateful to members of theNational Research Council staff who worked diligently tomaintain progress and quality in our work. Through herdedication, guidance, and skill, Charlotte Kirk Baer trans-formed our spirited verbal pondering and imperfect writ-ten drafts into a comprehensive report. Stephanie Padghamprovided able assistance and much-needed momentumduring the final stages of our study. Melinda Simons sup-ported all of us cheerfully and effectively during the earlyphases of the study and Laura Boschini shared her skillsin preparing the report for publication.

ix

This report has been reviewed in draft form by individu-als chosen for their diverse perspectives and technicalexpertise, in accordance with procedures approved by theNRCs Report Review Committee. The purpose of thisindependent review is to provide candid and critical com-ments that will assist the institution in making its publishedreport as sound as possible and to ensure that the reportmeets institutional standards for objectivity, evidence, andresponsiveness to the study charge. The review commentsand draft manuscript remain confidential to protect theintegrity of the deliberative process. We wish to thank thefollowing individuals for their review of this report: R. LeeBaldwin, University of California, Davis; Paul Chandler,Chandler Associates; Larry Chase, Cornell University; JudHeinrichs, Pennsylvania State University; Roger Hemken,University of Kentucky; Alois Kertz, Agri Brands Interna-tional; David Mertens, U.S. Department of AgricultureDairy Forage Research Center; Jerry Olson, University ofMinnesota; Leo Timms, Iowa State University; MichaelVan Amburgh, Cornell University; Harold Van Horn, Uni-versity of Florida; and Michael VandeHaar, Michigan StateUniversity. Although the reviewers listed above have pro-vided many constructive comments and suggestions, theywere not asked to endorse the conclusions or recommenda-tions nor did they see the final draft of the report before itsrelease. The review of this report was overseen by MichaelGalyean, Texas Tech University, appointed by the Commit-tee on Animal Nutrition, and Robert Wilson, MississippiState University, appointed by the Board on Agricultureand Natural Resources. These individuals were responsiblefor making certain that an independent examination ofthis report was carried out in accordance with institutionalprocedures and that all review comments were carefullyconsidered. Responsibility for the final content of thisreport rests entirely with the authoring subcommittee andthe institution.

Contents

OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

1 DRY MATTER INTAKE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Equations for Predicting DMI, 3

Lactating Cows, 3Growing Heifers, 6

Nutrients and Feeding Management Related to DMI of Lactating Dairy Cows, 6Moisture, 6Neutral Detergent Fiber, 7Forage to Concentration Ratio, 7Fat, 7

Cow Behavior, Management, and Environmental Factors Affecting Feed Intake, 8Eating Habits and Cow Behavior, 8Weather, 9Feeding MethodTotal Mixed Ration vs. Individual Ingredient, 9Feeding Frequency, 9Sequence of Feeding, 10Access to Feed, 10

References, 10

2 ENERGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Energy Requirements of Lactating and Pregnant Cows, 13

Energy Units, 13Energy Values of Feeds, 13

Estimating TDN of Feeds at Maintenance, 14Estimating DE of Feeds, 15Estimating DE at Actual Intake, 16Estimating ME at Actual Intake, 17Estimating NEL at Actual Intake, 17Estimating Net Energy of Feeds for Maintenance and Gain, 17Comparison of New NEL Values with Values from 1989 Edition, 18Precautions, 18

Energy Requirements, 18Maintenance Requirements, 18Lactation Requirements, 19Activity Requirements, 20

xi

xii Contents

Environmental Effects, 21Pregnancy Requirements, 21Tissue Mobilization and Repletion During Lactation and the Dry Period, 22Body Condition Scoring, 25

References, 25

3 FAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28Digestion and Absorption, 28Digestibility and Energy Value of Fats, 29Effects of Fat on Ruminal Fermentation, 30Utilization of Fat in Calf Diets, 30Fat in Lactation Diets, 30References, 32

4 CARBOHYDRATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34Nonstructural Carbohydrates, 34Structural Carbohydrates, 36

NDF Recommendations, 37ADF Requirement, 40

References, 40

5 PROTEIN AND AMINO ACIDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43Importance and Goals of Protein and Amino Acid Nutrition, 43

Major Differences from Previous Edition, 43Protein, 44

Chemistry of Feed Crude Protein, 44Mechanism of Ruminal Protein Degradation, 45Kinetics of Ruminal Protein Degradation, 46Nitrogen Solubility vs. Protein Degradation, 48Microbial Requirements for N Substrates, 48Animal Responses to CP, RDP, and RUP, 49Synchronizing Ruminal Protein and Carbohydrate Digestion:

Effects on Microbial Protein Synthesis, 52Ruminally Protected Proteins, 54Predicting Passage of Microbial Protein, 55Predicting Passage of Rumen Undegradable Feed Protein, 58Digestibility of Rumen Undegradable Feed Protein, 61Predicting Passage of Endogenous Protein, 63Evaluation of Model for Predicting Flows of N Fractions, 65Predicting Passage of Metabolizable Protein, 65

Metabolizable Protein Requirements, 67MP Requirements for Maintenance, 67Protein Requirements for Pregnancy, 68Protein Requirements for Lactation, 68Protein Requirements for Growth, 68

Amino Acids, 69Essential vs. Nonessential Amino Acids, 69Limiting Essential Amino Acids, 71Predicting Passage to the Small Intestine, 74Requirements for Lysine and Methionine in Metabolizable Protein for Lactating

Cows, 81Ruminally Protected Amino Acids, 85

References, 85

Contents xiii

6 MINERALS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105Macrominerals, 106

Calcium, 106Phosphorus, 109Sodium, 118Chlorine, 121Potassium, 124Magnesium, 128Sulfur, 131

Trace Minerals, 132Cobalt, 132Copper, 133Iodine, 136Iron, 138Manganese, 139Molybdenum, 140Selenium, 141Zinc, 143Chromium, 146Aluminum, Arsenic, Nickel, Silica, Tin, and Vanadium, 147

Toxic Minerals, 148Cadmium, 148Fluorine, 148Lead, 149Mercury, 149

References, 150

7 VITAMINS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162Fat-Soluble Vitamins, 162

Vitamin A, 162Vitamin D, 164Vitamin E, 166Vitamin K, 168

Water-Soluble Vitamins, 169B-Vitamins, 169

Biotin, 169Folic acid, 169Inositol, 169Niacin, 170Pantothenic Acid, 171Riboflavin (B2), 171Thiamin (B1), 171Vitamin B12, 172B-Vitamins-General, 172

Vitamin C, 172Choline, 173References, 174

8 WATER REQUIREMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178Water Intake, 178

Dry Cows, 179Calves and Heifers, 180Drinking Behavior, 180

xiv Contents

Water Quality, 180Summary, 182References, 182

9 UNIQUE ASPECTS OF DAIRY CATTLE NUTRITION . . . . . . . . . . . . .184Transition Cows and Nonlactating Cows, 184

Nutritional and Physiologic Status of the Transition Cow, 184Nutrient Requirements for Pregnancy, 185Nutrient Intake, 185Energy and Protein Density for Dry Cow Diets, 186

Etiology and Nutritional Prevention of Metabolic Disorders, 188Fatty Liver and Ketosis, 188Udder Edema, 189Milk Fever, 191Grass Tetany, 194Retained Placenta and Metritis, 194Displacement of the Abomasum, 196Rumen Acidosis and Laminitis, 197Milk Fat Depression, 199

Performance Modifiers, 201Mineral Salts and Their Role as Buffers, 201Ionophores, 201Direct Fed Microbials, 203Fungal Cultures, 203Bovine Somatotropin, 204

References, 205

10 NUTRIENT REQUIREMENTS OF THE YOUNG CALF . . . . . . . . . . .214Energy Requirements of Calves, 214

Young Replacement Calves Fed Milk or Milk Replacer Only, 215Young Replacement Calves Fed Milk and Starter Feed or Milk Replacer and

Starter Feed, 219Veal Calves, 220Ruminant Calves (Large-Breed and Small-Breed Females) from

Weaning to Body Weight of 100 kilograms, 220Effects of Environmental Temperature on Energy Requirements of Young

Calves, 220Protein Requirements of Calves, 221Mineral and Vitamin Requirements of Calves, 222

Minerals, 222Vitamins, 224

Feed Composition Data with Application to Diet Formulations for Calves, 225Other Aspects of Calf Nutrition, 226

Fetal Nutrition, 226Colostrum, 227Water and Electrolytes, 227Milk Replacers, 228Feed Additives, 228Practical Feeding Considerations, 229

References, 230

Contents xv

11 GROWTH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .234Energy and Protein Requirements for Growing Dairy Heifers, 234

Terminology, 234Growth Requirements and Composition of Gain, 234Evaluation of Model Predictions of Energy and Protein Requirements for

Growth of Dairy Heifers, 236Setting Target Growth Rates, 238

Evaluation of Target Weight Equations, 239Maintenance Requirement Effects on Growth, 239

Basal Maintenance Requirement, 240Adjustment for Previous Temperature, 240Adjustment for Previous Plane of Nutrition, 240Adjustment for the Direct Effects of Cold Stress, 241Adjustment for the Direct Effects of Heat Stress, 241Model Evaluation, 241

References, 242

12 DAIRY CATTLE NUTRITION AND THE ENVIRONMENT . . . . . . . .244Nitrogen, 245Phosphorus, 246Summary, 247References, 247

13 CARBOHYDRATE CHEMISTRY AND FEED PROCESSING . . . . . . .249Nonstructural Carbohydrates, 249Analytic Procedures, 249

Neutral Detergent Fiber, 249Neutral Detergent Insoluble Nitrogen, 250Acid Detergent Fiber, 250Acid Detergent Insoluble Nitrogen, 250Lignin, 250Total Nonstructural Carbohydrates, 251

Effects of Processing on Energy in Feed, 251Sources of Starch, 251Oilseeds, 254

References, 255

14 NUTRIENT REQUIREMENT TABLES . . . . . . . . . . . . . . . . . . . . . . . . .258

15 NUTRIENT COMPOSITION OF FEEDS. . . . . . . . . . . . . . . . . . . . . . . .281

16 MODEL EVALUATION AND PREDICTION EQUATIONS . . . . . . . .315

GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .334

USERS GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .341

ABOUT THE AUTHORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .361

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .363

Tables and Figures

TABLES

1-1 Validation statistics for prediction of dry matter intake by heifers, 6

1-2 Effect of bunk space per cow on feeding behavior and intake of early lactation cows, 9

2-1 Processing adjustment factors (PAF) for NFC, 14

2-2 True digestibility coefficients of CP used to estimate TDN1x values of animal-basedfeedstuffs, 15

2-3 True digestibilities at maintenance (assumed 8 percent increase in digestibility com-pared with 3X maintenance) of fatty acids from various fat sources, 15

2-4 Empty body (EB) chemical composition at different body condition scores (BCS),relative Eb weight (EBW), and NEL provided by live weight (LW) loss and NELneeded for LW gain, 24

2-5 Energy provided by or needed to change body condition score (BCS) of cows of differentlive weights and BCS, 25

3-1 Fatty acid composition and iodine values of fats and oils, 29

4-1 Nonstructural (NSC) and nonfiber (NFC) analyses of selected feedstuffs, 34

4-2 Composition of the NFC fraction of selected feedstuffs, 35

4-3 Recommended minimum concentrations (% of DM) of total and forage NDF andrecommended maximum concentrations (% of DM) of NFC for diets of lactatingcows when the diet is fed as a total mixed ration, the forage has adequate particlesize, and ground corn is the predominant starch source, 37

5-1 Studies used to evaluate milk and milk protein yield responses to changes in theconcentration of dietary crude protein, 50

5-2 Descriptive statistics for data set used to evaluate animal responses to CP and RDP, 50

5-3 Studies used to evaluate milk yield responses to changes in the concentration ofdietary ruminally degraded protein, 51

5-4 Studies used to determine the relationship between NEL intake and passage ofmicrobial protein to the small intestine of lactating dairy cows, 57

5-5 Studies reporting in situ determined estimates of N fractions and rates of proteindegradations that were used in preparing this edition, 60

xvi

Tables and Figures xvii

5-6 Recommended procedures and reporting details for a standardized in situ procedurefor measuring ruminal degradability of protein in dairy cattle, 62

5-7 Published studies that were summarized for the purpose of arriving at estimates ofintestinal digestibility of the RUP fraction of feedstuffs, 64

5-8 Studies used to validate the model equations for predicting flows of MCP, RUP plusECP, and NAN flows to the small intestine, 66

5-9 Mean percentage contributions of cysteine (and its oxidation product cystine) to totalsulfur amino acids (methionine cysteine cystine) and of tyrosine to tyrosine phenylalanine in ruminal microbes and feedstuff, 70

5-10 A comparison of the EAA profiles of body tissue and milk with that of ruminalbacteria and protozoa and common feeds, 72

5-11 Experiments used to develop equations for predicting amino acid passage to thesmall intestine, 76

5-12 Feedstuffs and the extent of their use in the 199 diets in the data set used todevelop equations to predict the content of individual EAA in total EAA of duodenalprotein, 76

5-13 Descriptive statistics of the data used for developing equations for predicting contentof individual EAA in total EAA of duodenal protein and for predicting flows of totalEAA to the small intestine, 77

5-14 Comparison of the root mean square prediction errors (RMSPE) obtained from plotsof residuals (predicted-measured vs. measured) for equations that predicted directlythe flow of each EAA with those accepted for use in the model that predicts directlythe percentage of each EAA in total EAA of duodenal protein, 80

5-15 Studies used to determine the dose-response relationships for lysine and methioninein metabolizable protein, 82

6-1 Comparison of estimated dietary copper requirements (mg/d) and dietary copperconcentrations (mg/kg of DM) for cattle in various physiologic states, 134

6-2 Calculated copper absorption coefficients across various dietary sulfur and molybde-num concentrations, 134

6-3 Comparison of estimated dietary manganese requirements (mg/d) and dietary manga-nese concentrations (mg/kg of DM) for cattle in various physiologic states, 141

6-4 Comparison of estimated dietary zinc requirements (mg/d) and dietary zinc concen-trations (mg/kg of DM) for cattle in various physiologic states, 145

7-1 Estimated absorption of selected B-vitamins from the small intestine compared withestimated requirements for tissue and milk synthesis of a 650-kg cow producing 35kg of 4 percent fat-corrected milk/day, 173

8-1 Guidelines for total soluble salts (TSS) in water for cattle, 180

8-2 Water hardness guidelines, 181

8-3 Nitrate in water, 181

8-4 Generally considered safe concentrations of some potentially toxic nutrients andcontaminants in water for cattle, 182

10-1 Daily energy and protein requirements of young replacement calves fed only milkor milk replacer, 215

xviii Tables and Figures

10-2 Daily energy and protein requirements of calves fed milk and starter or milk replacerand starter, 216

10-3 Daily energy and protein requirements of veal calves fed only milk or milkreplacer, 217

10-4 Daily energy and protein requirements of weaned (ruminant) calves, 218

10-5 Effect of environment on energy requirement of young calves, 221

10-6 Mineral and vitamin concentrations recommended in diets of young calves, comparedwith average for fresh whole milk (DM basis), 223

10-7 Energy, protein, calcium, and phosphorus concentrations in feedstuffs commonlyused in the formulation of milk replacers for young calves, 226

10-8 Energy, protein, fiber, and mineral composition of three milk replacers (MR), astarter feed, and a grower feed for young calves, 227

11-1 Relationships between mature size and growth requirements, 237

11-2 Calculation of target weights and daily gain using the data set of Van Amburgh etal. (1998a), 239

11-3 Application of equations to predict energy and protein requirements, using targetweights and daily gains from table 11-2, 240

11-4 Multipliers used to adjust the maintenance energy requirement to reflect variousenvironmental conditions, 241

11-5 Predicted effects of four environments on heifer performance, 242

14-1 Daily nutrient requirements of small breed cows (live weight 454 kg) in earlylactation, 260

14-2 Daily nutrient requirements of small breed cows (live weight 454 kg) inmidlactation, 261

14-3 Daily nutrient requirements of small breed cows (live weight 454 kg) inmidlactation, 262

14-4 Daily nutrient requirements of large breed cows (live weight 680 kg) in earlylactation, 263

14-5 Daily nutrient requirements of large breed cows (live weight 680 kg) inmidlactation, 264

14-6 Daily nutrient requirements of large breed cows (live weight 680 kg) inmidlactation, 265

14-7 Nutrient requirements of lactating dairy cows as determined using sample diets, 266

14-8 Nutrient requirements and required diet nutrient concentrations for fresh cows fedan example fresh-cow ration, 268

14-9 Nutrient requirements and diet concentrations needed to meet requirements fordry cows as determined using example diets, 270

14-10 Example diet incorporating dietary guidelines suggested in chapter 9 for transitioninga heifer during the later dry period to acclimate her to the lactating ration and toreduce metabolic disease, 272

14-11 Example diet incorporating dietary guidelines suggested in chapter 9 for transitioninga cow during the last weeks of gestation to acclimate her to a lactating ration andto reduce metabolic disease, 274

Tables and Figures xix

14-12 Daily nutrient requirements (DM basis) of small breed (mature weight 450 kg)non-bred heifers, 276

14-13 Daily nutrient requirements (DM basis) of large breed (mature weight 650 kg)non-bred heifers, 277

14-14 Daily nutrient requirements (DM basis) of small breed (mature weight 450 kg)bred heifers, 278

14-15 Daily nutrient requirements (DM basis) of large breed (mature weight 650 kg)bred heifers, 279

14-16 Nutrient requirements of growing Holstein heifers using model to predict targetaverage daily gain needed to attain a mature body weight of 680 kg, 280

15-1 Nutrient composition and variability of some feedstuffs commonly fed to dairycattle, 283

15-2a Nitrogen fractions, RUP digestibility, and amino acids of feedstuffs, 290

15-2b Nitrogen fractions and amino acid composition of less commonly used feedstuffs,which are cited in the literature but were not included as commonly used feedstuffsin Table 15-2a, 300

15-3 Mineral composition of some feedstuffs commonly fed to dairy cattle, 304

15-4 Compositions of inorganic mineral sources and element absorption coefficients fordairy cattle on a 100% dry matter basis, 311

16-1 Sources of data used in the model evaluation, 316

16-2 Ration densities of required minerals for three categories of feeds for calves, 331

UG-1 Summary report for diet A, 355

UG-2 Net energy and protein requirements of heifers with mature weights of 400, 650,and 800 kg, 357

UG-3 Effect of body weight and rate of gain on daily gain, 357

UG-4 Target weights for dairy heifers, 358

UG-5 Target daily gains post transition to pre-conception for three mature sizes of dairyheifers, 358

UG-6 Inputs for heifer growth exercises, 359

UG-7 Maintenance energy requirement multipliers for various environmental conditions, 359

FIGURES

1-1 Dry matter intake prediction of early lactation cows using equation 1-2 and Kertzet al. (1991) equations, 4

1-2 Dry matter intake, four percent fat corrected milk production, and body weightchange of primiparous and multiparous cows during 48 weeks of lactation, 5

1-3 Observed versus predicted dry matter intake of growing dairy heifers using beef calfequation from Nutrient Requirements of Beef Cattle (National Research Council,1996), 7

2-1 The relationship between feeding level expressed as multiples of maintenance andthe unit decline in diet TDN per multiple of maintenance where TDN percentageunit decline 0.18 10.3, r2 0.85, 16

xx Tables and Figures

2-2 Body condition scoring chart adapted from Edmonson et al. (1989), 23

5-1 Analyses of crude protein fractions using borate-phosphate buffer and acid detergentand neutral detergent solutions, 47

5-2 Response surface for data set described in Animal Responses to CP, RDP, andRUP section, 51

5-3 Plot of observed (open circles) and residuals (squares) for measured microbial Nflow (g/day) versus estimated NEL intake in lactating and dry dairy cows, 56

5-4 Relationship between measured efficiency of microbial protein synthesis (g microbialN/kg rumen fermented OM) and apparent ruminal N balance, 57

5-5 Plot of adjusted (open circles) and residuals (squares) for measured microbial N (g/day) versus measured total tract digestible OM (kg/d), 58

5-6 Plot of predicted vs. measured (filled circles) and residuals (predicted measured;open circles) vs. measured flows of microbial N to the small intestine of dairy cows, 66

5-7 Plot of predicted vs. measured (filled circles) and residuals (predicted measured;open circles) vs. measured flows of NANMN (rumen undegradable N plus endoge-nous N) to the small intestine of dairy cows, 66

5-8 Plot of predicted vs. measured (filled circle) and residuals (predicted measured;open circles) vs. measured flows of NAN (microbial N rumen undegradable N endogenous N) to the small intestine of dairy cows, 67

5-9 Plot of predicted vs. measured (filled circles) and residuals (predicted-measured;open circles) vs. measured (Lys, g/d) (from predicted Lys, percent of EAA andpredicted EAA, g/d), 79

5-10 Plot of predicted vs. measured (filled circles) and residual (predicted-measured; opencircles) vs. measured Met, g/d (from predicted Met, percent of EAA and predictedEAA, g/d), 79

5-11 Plot of predicted vs. measured (filled circles) and residuals (predicted-measured;open circles) vs. measured flow of total EAA, 79

5-12 Milk protein content responses as a function of digestible Lys and Met concentrationsin MP, 84

5-13 Milk protein yield responses as a function of digestible Lys and Met concentrationsin MP, 84

9-1 Dietary concentrations of crude protein needed in diets fed to transition cows tomeet requirements, 187

9-2 Dietary concentrations of NEL needed in diets fed to transition cows to meet require-ments, 188

10-1 Example of growth rate predicted by the model in this edition for a 40-kg calf fedwhole milk (open bars) or a milk replacer (dark bars) at 10, 14, or 18 percent ofbody weight, 229

16-1 Model predicted vs. actual dry matter intake, 316

16-2 NEL intake (estimated from observed dry matter intake and model estimated NELconcentration) versus NEL use (estimated from model predicted maintenance andlactation requirement plus NEL needed to meet observed body weight change), 317

16-3 Actual milk production versus model predicted MP allowable milk production, 317

Tables and Figures xxi

16-4 Difference between MP allowable milk and actual milk versus model predicted lysineconcentration of MP, 317

16-5 Difference between MP allowable milk and actual milk versus model predictedmethionine concentration of MP, 317

UG-1 Settings for number properties, 344

UG-2 Settings for currency, 345

UG-3 Program menu bar, 346

UG-4 Help box, 348

UG-5 Program settings screen, 348

UG-6 Animal description screen, 349

UG-7 Production screen, 349

UG-8 Management/Environment screen, 350

UG-9 Feed screen, 350

UG-10 Ration screen, 352

UG-11 Reports screen, 352

NutrientRequirementsof Dairy CattleSeventh Revised Edition, 2001

Overview

Since 1944, the National Research Council has pub-lished six editions of Nutrient Requirements of Dairy Cat-tle. This seventh revised edition, Nutrient Requirements ofDairy Cattle 2001, applies new information and technologyto current issues in the field of dairy cattle production.Reflecting the rapidly changing face of dairy cattle produc-tion and dairy science, it includes more comprehensivedescriptions of management and environmental factorsthat affect nutrient requirements and provides expandeddiscussions of nutrient needs for various life stages andlevels of production. A revised approach to predictingnutrient requirements increases the users responsibilityfor accurately defining animals, diet, and management con-ditions to estimate nutrient requirements. A benefit associ-ated with the increased responsibility is the ability of theuser to make more-informed decisions in the field.

A substantial part of the increase in decision-makingpower comes from the presentation of requirements witha computer model. Computer models are the only effectivemeans of taking animal variation into account. Unlike statictabular values, computer models such as the one providedin this edition can describe animals in different states withdiffering needs. A model can accommodate fluctuationscaused by the effect of feed ingredients on nutrient absorp-tion and consequently on the animals performance poten-tial, which affects its nutrient requirements. The modelprepared in this publication was designed to provide practi-cal, situation-specific information in a user-friendly format.

Chapter 1 presents a discussion of dry matter intake,including factors that affect intake and methods of predict-ing it. Characteristics of the animals diet, environment,and physiologic makeup are considered, as are relevantmanagement issues. After a brief description of availableequations for predicting dry matter intake, the chapterdiscusses the dry matter intake equations included in thisedition and closes with tables and graphs of intake acrossa lactation.

1

Chapter 2 addresses energy, defining energy units andexpressing methods of obtaining, estimating, and express-ing energy values of feeds. The chapter discusses energyrequirements for maintenance, lactation, activity, and preg-nancy. Tissue mobilization and repletion and the effectsof environment are discussed. The chapter concludes witha section on body condition scoring, which is accompaniedby a reference chart.

Chapter 3 covers digestibility and energy values of fat.It contains information on effects of fat on rumen fermenta-tion and the use of fat in lactation diets. A table of fattyacid composition of fats and oils is presented.

A comprehensive review of carbohydrates is providedin Chapter 4. Nonstructural and structural carbohydratesare discussed, with special attention to requirements forneutral detergent fiber (NDF) and acid detergent fiber(ADF).

Chapter 5 covers all aspects of protein and amino acidnutrition. This chapter documents an extensive literaturebase used in the development of equations and providesdetailed explanations for estimating metabolizable-proteinrequirements for maintenance, pregnancy, lactation, andgrowth. The amino acid section is a substantial advanceover the previous edition and provides readers with adiscussion of predicting passage to the small intestineand equations for estimating lysine and methioninerequirements.

Requirements for macrominerals and trace minerals,and information on toxic minerals appear in Chapter 6.Each category includes an extensive list of minerals andcovers their function, bioavailability, requirements by dif-ferent classes of dairy animals, toxicity, and symptoms ofmineral deficiency.

Chapter 7 covers vitamins in a similar fashion, dividingthem into fat-soluble and water-soluble categories. Likethe minerals in Chapter 6, the vitamins in Chapter 7 are

2 Overview

discussed in the context of the animals that will be ingestingthem. Sources and bioavailability of vitamins are provided,followed by a discussion of the functions of each vitamin,animal response to it, requirements for it, and factors thataffect the requirements.

Metabolism and requirements open the discussion ofwater in Chapter 8. This chapter furnishes information onfactors in the environment and the water itself that affectintake. Among the factors considered are nutrients in thewater and the presence of bacteria and algae.

Chapter 9 addresses important issues peculiar to dairynutrition. It considers the feeding of the transition cow,metabolic disorders (such as udder edema and milk fever),and performance modifiers (such as buffering agents anddirectly fed microbials).

Chapter 10 offers information specifically on the nutri-ent requirements of the young calf and Chapter 11 on theheifer, and aspects of growth, maturity, and body reserves.

One of the most important features of this revision isthe inclusion of a discussion on the effect of dairy cattlefeeding on the environment. Chapter 12 provides an over-view of nutrients of concern and applies science to thechallenges faced by managers in reducing nutrientexcretion.

Chapter 13 provides a discussion of feed chemistry andprocessing. Analytic procedures are described, and theeffects of processing on energy in feed are reviewed.

Nutrient requirement tables are presented in Chapter14. These tables were generated with the accompanyingcomputer model. Tables are provided for small- and large-breed cows at various stages of lactation.

Chapter 15 provides a greatly expanded set of feed com-position tables and an explanation of their use. The tablesinclude nutrient breakdowns for a comprehensive list offeedstuffs commonly present in dairy cattle diets and somefeeds that are less common.

Chapter 16 presents an evaluation of the computermodel. Data from experiments in which 100 different dietswere fed in continuous feeding trials and published in theJournal of Dairy Science were used in the evaluation. Afterthe evaluation, the anatomy and use of prediction equationsin the computer program are presented. An introductionto this editions computer model is present in a users guide.

Finally, a glossary of terms used in this edition is pro-vided to increase readers ease of use and comprehension.

Although the science base for predicting nutrientrequirements summarized here has greatly expanded sincethe previous edition of this report, there are still gaps inour knowledge, particularly for specific animals of differentages and levels of production. The users of this volumeare encouraged to seek a firm understanding of the princi-ples and assumptions described here, because this under-standing is essential for proper use of the tables and textand of the computer model and its output.

The estimates of nutrient requirements that are pre-sented in this report for different classes of animals weregenerated as examples and are intended for use as guide-lines by professionals in diet formulation. Because thereare many factors that affect requirements of animals undervarious conditions, the values presented here cannot beconsidered all encompassing and should not be interpretedas accurate or applicable in all situations.

1 Dry Matter IntakeDry matter intake (DMI) is fundamentally important in

nutrition because it establishes the amount of nutrientsavailable to an animal for health and production. Actualor accurately estimated DMI is important for the formula-tion of diets to prevent underfeeding or overfeeding ofnutrients and to promote efficient nutrient use. Underfeed-ing of nutrients restricts production and can affect thehealth of an animal; overfeeding of nutrients increases feedcosts, can result in excessive excretion of nutrients into theenvironment, and at excessively high amounts may be toxicor cause adverse health effects.

Many factors affect voluntary DMI. Individual theoriesbased on physical fill of the reticulorumen (Allen, 1996;Mertens, 1994), metabolic-feedback factors (Illius and Jes-sop, 1996; Mertens, 1994), or oxygen consumption (Kete-laars and Tolkamp, 1996) have been proposed to determineand predict voluntary DMI. Each theory might be applica-ble under some conditions, but it is most likely the additiveeffect of several stimuli that regulate DMI (Forbes, 1996).

Feeds low in digestibility are thought to place constraintson DMI because of their slow clearance from the rumenand passage through the digestive tract. The reticulorumenand possibly the abomasum have stretch and touch recep-tors in their walls that negatively impact DMI as the weightand volume of digesta accumulate (Allen, 1996). The neu-tral detergent fiber (NDF) fraction, because of generallylow rates of digestion, is considered the primary dietaryconstituent associated with the fill effect.

The conceptual framework for the metabolic-feedbacktheory contends that an animal has a maximal productivecapacity and maximal rate at which nutrients can be usedto meet productive requirements (Illius and Jessop, 1996).When absorption of nutrients, principally protein andenergy, exceeds requirements or when the ratio of nutri-ents absorbed is incorrect, negative metabolic-feedbackimpacts DMI.

An alternative to the metabolic theory is the theory Kete-laars and Tolkamp (1996) proposed based on oxygen con-sumption. This theory suggests that animals consume net

3

energy at a rate that optimizes the use of oxygen andminimizes production of free radicals that lead to aging.

In addition to the complexity and interaction of thephysical, metabolic, and chemostatic factors that regulateDMI is the psychologic and sensory ability of animals (Bau-mont, 1996). Consistently accurate prediction of DMI inruminants has been difficult to achieve because a compli-cated, diffuse, and poorly understood set of stimuli regulateDMI. For additional discussions and reviews on intake,see Baile and McLaughlin (1987); Forbes (1995); Ketelaarsand Tolkamp (1992a,b); Mertens (1994); NationalResearch Council (1987).

In lactating dairy cattle, milk production (energy expen-diture) usually peaks 4 to 8 weeks postpartum, and peakDMI (energy intake) lags until 10 to 14 weeks postpartum(National Research Council, 1989). It has been debatedwhether milk production is driven by intake or intake isdriven by milk production. On the basis of energy intakeregulation theory and others (Baile and Forbes, 1974; Con-rad et al., 1964; Mertens, 1987; National Research Council,1989), cows appear to consume feed to meet energy needs,so intake is driven by milk production.

This increase in energy intake in response to energyexpenditure has been clearly shown in the numerous lacta-tion studies with bovine somatotropin where DMI followsmilk production (Bauman, 1992; Etherton and Bauman,1998).

E QU AT I ON S F O R P RE D IC TI N G D MI

Lactating Cows

Earlier editions of Nutrient Requirements of Dairy Cat-tle used various approaches to predict DMI. The 1971edition (National Research Council, 1971) simply recom-mended feeding ad libitum during the first 6 to 8 weeksof lactation, and then feeding to energy requirements afterthat for lactating dairy cows. In 1978 (National Research

4 Nutrient Requirements of Dairy Cattle

Council, 1978), DMI guidelines were established by usinga set of selected studies to create an interpolation table.Body weight and 4 percent fat-corrected milk were factorsused to estimate DMI, which ranged from 2 to 4 percent ofbody weight. The 1989 edition (National Research Council,1989) predicted DMI on the basis of energy requirementtheory and expressed it simply as

DMI (kg) NEL required (Mcal)

NEL concentration of diet (Mcal/kg)(1-1)

where net energy of lactation (NEL) included requirementsfor maintenance, milk yield, and replenishment of lostweight. Suggested modifications for expected DMI werean 18 percent reduction during the first 3 weeks of lactationand DMI reduction of 0.02 kg per 100 kg of body weightfor each 1 percent increase in moisture content of the dietabove 50 percent when fermented feeds were being fed.The DMI guidelines in the 1989 publication were basedentirely on energy balance (that is, over the long term,energy intake must equal energy expenditure). The methodwas not designed to estimate daily DMI in the short term.It required accurate estimates of changes in body tissuemass (although the equation was based on changes in bodyweight, it assumed that body weight changes equaledchanges in body tissue mass) and accurate estimates of theconcentration of NEL in the diet. Because of changes ingut fill and inaccurate measurements, short-term changesin body tissue mass and the energy needed or providedbecause of those changes are difficult to measure accu-rately, as is the concentration of NEL in the diet. Toimprove the utility of this report, the present subcommitteedecided to include an empirical equation to estimate short-term DMI.

Several DMI prediction equations have been developedfor use in the field, but only a few have been publishedin the scientific literature and tested for accuracy (Fuentes-Pila et al., 1996; Roseler et al., 1997a). The equationsreported in the literature are based on the principle thatanimals consume dry matter to meet energy requirementsor are developed by regression of various factors againstobserved DMI. DMI prediction equations that includeanimal, dietary, or environmental factors have been devel-oped by Holter and Urban (1992) and Holter et al. (1997).

In the approach used to develop DMI prediction equa-tions in this edition, DMI prediction is based on actualdata with the inclusion of only animal factors, which wouldbe easily measured or known. Dietary components werenot included in models for lactating cows, because theapproach most commonly used in formulating dairy cattlediets is to establish requirements and a DMI estimatebefore dietary ingredients are considered. Equations con-taining dietary factors are best used to evaluate postcon-sumption rather than to predict what will be consumed.

DMI data published in the Journal of Dairy Sciencefrom 1988 to 1998 (see Chapter 16 for references) anddata from Ohio State University and the University ofMinnesota (May, 1994) were used in evaluating and devel-oping an equation for lactating Holstein dairy cows. Thedata set included 17,087 cow weeks (5962 first lactation and11,125 second lactation or greater cow weeks), a diverse setof diets, and studies with and without bovine somatotropinand encompassed a 10-year period from 1988 to 1997.Weeks of lactation ranged from 1 to 80; most data werefrom 1 to 40 weeks. Equations evaluated were those ofRoseler et al. (1997b) and May (1994) and an equationreported by Rayburn and Fox (1993) based on DMI valuesin the 1989 Nutrient Requirements of Dairy Cattle(National Research Council, 1989). The best overall predic-tion equation, based on bias (0.27 kg/day) and meansquare prediction error (3.31 kg2/day) was a combinedequation of Rayburn and Fox (1993) and an adjustmentfor week of lactation developed by Roseler et al. (1997b).The equation for predicting DMI of lactating Holsteincows is

DMI (kg/d) (0.372 FCM 0.0968 BW0.75) (1 e(0.192(WOL3.67))) (1-2)

where FCM 4 percent fat corrected milk (kg/day), BW body weight (kg), and WOL week of lactation. Theterm 1 e(0.192(WOL3.67)) adjusts for depressed DMI dur-ing early lactation. For early lactation cows, Equation 1-2was compared to those developed by Kertz et al. (1991)using the validation data from Kertz et al. (1991). Drymatter intake predictions for the first 14 weeks of lactationare shown in Figure 1-1. Equation 1-2 predicts DMI veryclosely to the actual DMI for the first 10 weeks of lactationand then slightly under predicts DMI thereafter comparedto the general overall predictions of Kertz et al. (1991).

FIGURE 1-1 Dry matter intake prediction of early lactationcows using Equation 1-2 and Kertz et al. (1991) equations.

Dry Matter Intake 5

Equation 1-2 is based entirely on Holstein cows. Nopublished DMI data were available for developing or modi-fying the current equation for use with breeds other thanHolstein. For DMI of Jersey cattle, readers are referredto Holter et al. (1996).

No adjustment to the DMI equation for parity is needed.The bias and mean square prediction error for primiparous(0.16 kg/day and 3.05 kg2/day) and multiparous (0.12 kg/day and 3.20 kg2/day) were similar and were not differentfrom the overall combined prediction equation statistics.However, body weight and milk production data appro-priate for first and second lactation animals must be used inthe equation to estimate DMI accurately for these animals.

The actual DMI, FCM, and body weight data fromanimals used to develop and validate the lactating cowDMI prediction equation are shown in Figure 1-2. Body

5

10

15

20

25

30

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46

WEEK OF LACTATION

DR

Y M

ATTE

R IN

TAKE

(kg/da

y)

Dry Matter Intake(Multiparous Cows)

Dry Matter Intake(Primiparous Cows)

5

15

25

35

45

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46WEEK OF LACTATION

4% F

AT C

ORR

ECTE

D M

ILK

(kg/da

y) 4% Fat Corrected Milk(Multiparous Cows)

4% Fat Corrected Milk(Primiparous Cows)

450

500

550

600

650

700

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49WEEK OF LACTATION

BODY

WEI

GHT

, kg

PrimiparousMultiparous

a

b

c

FIGURE 1-2 a) Dry matter intake, b) 4 percent fat corrected milk production, and c) body weight change of primiparous andmultiparous cows during 48 weeks of lactation.

weight change is based on animals becoming pregnantby week 17 of lactation, so later weights reflect cow andconceptus gain during the lactation.

The DMI of lactating cows is affected by environmentalconditions outside the thermal neutral zone (5 to 20C).Both Eastridge et al. (1998) and Holter et al. (1997) haveshown DMI decreases with temperatures above 20C. Theequation used for predicting DMI of lactating cows (Equa-tion 1-2) in this edition does not include a temperature orhumidity adjustment factor because of insufficient DMIdata outside of the thermal neutral zone to validate equa-tion modifiers. However, use of lowered milk productionin Equation 1-2 during heat stress periods will reflect thereduction in DMI commonly observed during heat stressperiods. Eastridge et al. (1998) suggested the followingchanges occur in DMI when temperatures are outside of

6 Nutrient Requirements of Dairy Cattle

the thermal neutral zone; temperatures 20 C, DMI (1 (( C 20) 0.005922)) and temperatures 5 C,DMI/(1 ((5 C) 0.004644)). Application of theEastridge et al. (1998) adjustment factors to a DMI predic-tion from Equation 1-2 based on lowered milk productionduring periods of heat stress may result in an excessivelylow prediction of DMI.

Growing Heifers

Published data on DMI of growing heifers weighingfrom 60 to 625 kg are sparse. Most research studies usedfewer than 40 animals with a narrow weight range andlimited experimental observation period. Dry matter intakeequations from Quigley et al. (1986) and Stallings et al.(1985) and calf equation from the Nutrient Requirementsof Beef Cattle (National Research Council, 1996) wereselected for initial evaluation using data from New Hamp-shire and Minnesota where dietary composition, heifergrowth, and DMI were measured over several months.The equation of Quigley et al. (1986) and the NutrientRequirements of Beef Cattle equation (National ResearchCouncil, 1996) include dietary energy content and bodyweight. An equation based only on animal parameters waspreferred to one including dietary components, however,the only published heifer DMI equation without dietarycomponents found was from Stallings et al. (1985). Onevaluation, the limited animal parameter equation of Stall-ings et al. (1985) was found to have a much larger predictionerror, especially for heifers above 350 kg, than either theQuigley et al. (1986) or the National Research CouncilsNutrient Requirements of Beef Cattle (1996) equation,which had similar predictive accuracy (Table 1-1).

Because of more current evaluation and a much largervalidation data set than Quigley et al. (1986), the equationfor beef calves from the 1996 Nutrient Requirements ofBeef Cattle (National Research Council, 1996) was furthervalidated using a data set from Purina Mills, St. Louis,Missouri. This data set included 2727 observations ongrowing heifers ranging from 58 to 588 kg and dietarynet energy-maintenance concentrations from 1.24 to 1.55Mcal/kg. Based on the fit of the data from the initial evalua-tion and the validation (Figure 1-3), the National Research

TABLE 1-1 Validation Statistics for Prediction of DryMatter Intake by Heifers

Equation source Bias, kg/d MSPE,a kg2/d

Quigley et al. (1986) 0.32 1.47Stallings et al. (1985) 1.32 1.90National Research Councilb (1996) Calves 0.51 1.48

aMean square prediction error.bNutrient Requirements of Beef Cattle (National Research Council, 1996).

Council equation for beef cattle is recommended for pre-dicting DMI of growing, nonlactating Holstein heifers.

DMI (kg/d) (BW0.75 (0.2435 NEM 0.0466 NEM2

0.1128)/NEM) (1-3)

where BW body weight (kg) and NEM is net energy ofdiet for maintenance (Mcal/kg).

No adjustments for breed, empty body fat, feed addi-tives, or anabolic implant were made. There is a consider-able difference in the DMI predicted from the growingheifer equation (Eq. 1-3) during late gestation and theequation used to predict DMI of heifers the last 21 daysof gestation (Eq. 9-1, Chapter 9). To avoid a large discon-nect in DMI between days 260 and 261 in the model, thefollowing adjustment factor for Equation 1-3 based on daysof gestation is applied to Equation 1-3: [1 ((210DG) 0.0025)]; where DG day of gestation. The adjustmentis applied for utility in model usage and is not validated.Reported information on DMI of growing heifers duringthe last trimester of pregnancy is nonexistent.

Data for predicting DMI of growing heifers for breedsother than Holstein or adjusting Equation 1-3 to fit otherbreeds was not found. Likewise, there is a dearth of infor-mation for developing adjustments to Equation 1-3 fortemperature and other environmental factors. Fox andTylutki (1998) modified the temperature and mud adjust-ments listed in the Nutrient Requirements of Beef Cattle(National Research Council, 1996) for growing dairy heif-ers, but did not validate the adjustments because of thelack of data. Hoffman et al. (1994) have shown that season,type of housing, muddy conditions, length of hair, and bodycondition all affect average daily gain; and adjustments toenergy requirements for gain were suggested, but effectson DMI were not evaluated.

N UT RI E NT S A N D F EE D IN GM AN AG E ME NT R EL AT E D T O D M IO F L AC T AT IN G DA IR Y CO WS

Moisture

Studies reviewed by Chase (1979) and included in the1989 Nutrient Requirements of Dairy Cattle (NationalResearch Council, 1989) indicate a negative relationshipbetween DMI and diets high in moisture content. Adecrease in total DMI of 0.02 percent of body weight foreach 1 percent increase in moisture content of the dietabove 50 percent was indicated when fermented feedswere included in the ration. In a study using alfalfa silageto vary dietary DM, Kellems et al. (1991) found a trendof reduction in DMI with increasing moisture in the diet.Holter and Urban (1992) summarized data on 329 lactating

Dry Matter Intake 7

FIGURE 1-3 Observed versus predicted dry matter intake ofgrowing dairy heifers using beef calf equation from NutrientRequirements of Beef Cattle (National Research Council, 1996).

cows fed diets ranging from 30 to 70 percent DM andfound that DMI was not decreased when dietary DMdecreased to below 50 percent. Most high moisture feedsare fermented, and the decrease in DMI when they arefed is generally thought to result from fermentation endproducts and not water itself. When cows were given dietsidentical in composition except for the addition of water(78, 64, 52, or 40 percent DM in diets), DMI of cowsincreased linearly (P 0.01) as percentage DM in theration increased (Lahr et al., 1983). However, DMI wasnot affected by soaking grain mixes in water to achieve adietary DM of 35, 45, or 60 percent (Robinson et al., 1990).Published reports on the relationship between dietary DMcontent and DMI are conflicting and no optimum DMcontent of the diet for maximum DMI is apparent.

Neutral Detergent Fiber

Mertens (1994) suggested that NDF be used to definethe upper and lower bounds of DMI. At high NDF concen-trations in diets, rumen fill limits DMI whereas, at lowNDF concentrations energy intake feedback inhibitorslimit DMI. Dado and Allen (1995) demonstrated the fillrelationship in cows during early lactation: 35 percent NDFdiets restrict DMI because of feed bulkiness and rumenfill, but DMI was not limited when 25 percent NDF dietswere fed with or without inert bulk in the rumen. In areview on feed characteristics affecting DMI of lactatingcattle, Allen (2000) summarized 15 studies and showed ageneral decline in DMI with increasing NDF concentra-tions in diets when diets exceeded 25 percent NDF. Atany particular NDF concentration in the diet, however, aconsiderable range in DMI was observed suggesting the

source or sources of NDF in the diet as affected by particlesize, digestibility, and rate of passage from the reticulo-rumen affect DMI.

The use of NDF as a variable in DMI prediction modelshas been reviewed in two studies. Rayburn and Fox (1993)concluded that DMI prediction was most accurate andleast biased when dietary NDF, particularly from forages,was included in a model with BW, FCM, and days in milk.However, in models for predicting DMI of lactating cowsfed high energy diets ranging in NDF from 25 to 42 percentof DM, less than 1 percent of the variation in DMI wasaccounted for by dietary NDF (Roseler et al., 1997a).

Forage to Concentrate Ratio

The ratio of forage to concentrate (F:C) in lactating dairycow diets has been reported to affect DMI. Many of thestudy results are probably associated with the amount anddigestibility of forage fiber and a propionate limiting effecton DMI as discussed by Allen (2000), rather than a specificratio of forage to concentrate. In alfalfa or orchardgrassbased diets, cows fed concentrate as 20 percent of thedietary DM produced less milk (P 0.01) than cows feddiets that contained 40 or 60 percent concentrate (Weissand Shockey, 1991). The DMI increased linearly (P 0.01) with increasing concentrate in diets regardless offorage type. Digestible DM also increased linearly (P 0.01) with increasing concentrate in the diet. Becauseintake of undigested DM was not affected by the amountof concentrate, rates of passage and digestion and physicalcharacteristics of the feedstuffs are probable causes of dif-ferences in DMI.

Llamas-Lamas and Combs (1991) fed diets with threeratios of forage (alfalfa silage) to concentrate (86:14, 71:29,and 56:44). DMI was greatest for the diet highest in con-centrate but similar for the other two diets. Petit and Veira(1991) fed concentrate at either 1.3 or 1.8 percent of BWand alfalfa silage ad libitum (F:C, 63:37 and 54:46) toHolstein cows during early lactation. Both groups of cowsate similar amounts of silage, but cows consuming the high-concentrate diet gained weight, and animals consumingthe low-concentrate diet lost weight. Similar results wereobserved by Johnson and Combs (1992): cows fed a 74percent forage diet (2:1 alfalfa silage to corn silage) con-sumed 2.7 kg less DM per day than cows fed a diet contain-ing 50 percent forage. In general, increasing concentratein diets up to about 60 percent of the DM increased DMI.

Fat

Assuming that cows consume DM to meet their energyrequirements (Baile and Forbes, 1974; Mertens, 1987;National Research Council, 1989), often less DM is con-sumed when fat replaces carbohydrates as an energy source

8 Nutrient Requirements of Dairy Cattle

in diets (Gagliostro and Chilliard, 1991). Fats may alsodecrease ruminal fermentation and digestibility of fiber(Palmquist and Jenkins, 1980; Chalupa et al., 1984, 1986)and so contribute to rumen fill and decrease the rate ofpassage. Allen (2000) also indicated fats may contribute todecreased DMI through actions on gut hormones, oxida-tion of fat in the liver and the general acceptability of fatsources by cattle.

The response in DMI to the addition of fatty acids inlactating dairy cattle diets is dependent on the fatty acidcontent of the basal diet and source of added fatty acids(Allen, 2000). For the diets containing 5 to 6 percent totalfatty acids, the addition of oilseeds and hydrogenated fattyacids to diets resulted in a quadratic effect on DMI withminimums occurring at 3 and 2.3 percent added fatty acids,respectively. Additions of tallow, grease, and calcium saltsof palm fatty acids to diets resulted in a general negativelinear decrease in DMI. Smith et al. (1993) reported rumi-nally active fats have a greater negative effect on DMI,ruminal fermentation, and digestibility of NDF when dietsare high in corn silage than when they are high in alfalfa hay.

Palmquist and Jenkins (1980) indicated that increasedsaturation of fatty acids usually reduces the negative rumi-nal effects associated with fats. However, Allen (2000)found that as the proportion of unsaturated fatty acids inthe fat source increased, DMI generally decreased. Mostall of the studies that Allen (2000) cited fed the calciumsalts of palm fatty acids. However, total digestible energyintake in many of the studies was not reduced, as digestibil-ity of the calcium salts of palm fatty acids was high andgreater than hydrogenated palm fatty acid comparisons.

While the trend is for a reduction in DMI with theaddition of fatty acids to diets (Allen, 2000; Chan et al.,1997; Elliot et al., 1996; Garcia-Bojalil et al., 1998; Jenkinsand Jenny, 1989; Rodriguez et al., 1997), some studies(Pantoja et al., 1996; Skaar et al., 1989) have reportedincreases in DMI. Potential reasons for increased DMIwith fat addition is a lower heat increment during periodsof heat stress and/or a reduction in propionate inhibitionon DMI when fat is substituted for grain (Allen, 2000).

C OW BE H AV IO R , M AN A GE ME N T, AN DE NV IR O NM EN T AL FA C TO RS A FF EC T IN GF EE D I N TA KE

Eating Habits and Cow Behavior

Dado and Allen (1994) studied eating habits of lactatingdairy cows housed in a tie-stall barn. Twelve Holstein cowsranging in milk production from 22 to 45 kg/d were moni-tored during the ninth week of lactation. The six highest-producing cows averaged 11 kg more milk per day andconsumed about 6 kg more DM per day than the lowest-

producing six cows. The time spent eating (average, 300minutes/day) and the number of meals (average, 11/day)did not differ between the two groups, but the high-pro-ducing cows consumed more DM per meal than did thelow-producing cows (2.3 vs. 1.7 kg). High-producing cowsruminate fewer times per day (13 vs. 14.5 times/day) butruminate an average of 5 min more per rumination periodthan low-producing cows.

Grouping cows according to their nutrient requirementscan decrease the variation in DMI among cows withinthe group. The DMI shown in Figure 1-2 illustrates thedifference between primiparous and multiparous cows intotal DMI and pattern of DMI during lactation. Primipa-rous cows do not peak in DMI as early in lactation, but theyare more persistent in DMI after peak than are multiparouscows. Thus, primiparous and multiparous cows should begrouped separately because of differences in DMI andsocial hierarchy. Primiparous cows are usually more timidand of lower social rank in the herd initially, but theygradually rise in social rank as more cows enter the herdor as older cows leave (Wierenga, 1990). Phelps and Drew(1992) reported an increase of 725 kg in milk over a 305-day lactation for first-lactation animals when grouped sepa-rately instead of being mixed in with older cows.

Behavior at the feed bunk is often affected by socialdominance. Dominant cows, usually older and larger, tendto spend more time eating than do cows with a lower socialrank in a competitive situation , such as when bunk spaceis restricted (Albright, 1993). Socially dominant animals,not necessarily the highest producers, tend to consumemore feed at the bunk in these situations (Friend andPolan, 1974). In a situation of competition for feed, cowsconsume slightly more feed but do it in less time per daythan when there is no competition and access to feed isample (Olofsson, 1999).

In 1993, Albright (1993) recommended at least 46 cmof bunk space per cow. Friend et al. (1977) evaluated bunkspaces of 50, 40, 30, 20, and 10 cm per cow, for earlylactation cows with mature equivalent productions of 7,700to 10,000 kg/year. Average time spent at the feed bunk(3.7 hours/day) did not decrease until only 10 cm of spaceper cow was available (Table 1-2). When there was 20 or10 cm per cow, the correlation of dominance to durationof eating periods increased. The optimal or critical feedbunk space needed is probably not a constant numberand will depend on competition between cows, the totalnumber of cows having access to the feed space, and theavailability of feed over a 24-hour period.

For growing dairy heifers, feed-bunk space requirementvaries with age. Longenbach et al. (1999) found that rapidgrowth in growing heifers fed a total mixed diet could bemaintained in young heifers (4 to 8 months old) with 15cm of bunk space. But, by the age of 17 to 21 months,

Dry Matter Intake 9

TABLE 1-2 Effect of Bunk Space Per Cow onFeeding Behavior and Intake of Early Lactation Cowsa

Feed Bunk Length Per Cow (cm)

50 40 30 20 10

Time at feed bunk, h 3.82 3.73 3.73 3.76 2.57b

Correlation of time with 0.46 0.32 0.30 0.67c 0.71d

social dominancePercentage of time at feed 21.5 26.9 34.6 51.9 70.6

bunk, %Daily feed intake, kg of DM 17.5 17.6 17.8 16.9 15.7

aFrom Friend et al. (1977).bDiffers from 50 cm feed bunk/cow.cDiffers from zero (P 0.05).dDiffers from zero (P 0.01).

feed bunk space needed to be similar (47 cm) to thatrecommended for lactating cows.

Cattle prefer mangers that allow them to eat off a smoothsurface in a natural grazing position. Albright (1993) citedevidence showing cows eating with their heads down pro-duce 17 percent more saliva than cows eating with theirheads in a horizontal position. Feed-wasting activities asso-ciated with elevated bunks, such as feed tossing, are elimi-nated when cows eat with their heads down (Albright,1993).

Weather

The thermal neutral zone of dairy cattle is about 5 to20 C, but it varies among animals. Temperatures below orabove the thermal neutral range alter intake and metabolicactivity. Young (1983) stated ruminants adapt to chroniccold stress conditions by increasing thermal insulation,basal metabolic intensity, and DMI. Rumination activity,reticulo-rumen motility, and rate of passage are alsoincreased (Young, 1983). However, in extreme cold, DMIdoes not increase at the same rate as metabolism, so animalsare in a negative energy balance and shift energy use fromproductive purposes to heat production.

A rise in ambient temperature above the thermal neutralzone decreases milk production because of reduced DMI.Holter et al. (1997) found pregnant multiparous middle-to late-lactation Holstein cows decreased DMI more (22percent) than primiparous cows (9 percent) at the samestage of lactation and pregnancy when subjected to heatstress. A decrease in DMI up to 55 percent of that eatenin the thermal neutral zone along with an increase of 7 to25 percent in maintenance requirement has been reportedfor cows subjected to heat stress (National Research Coun-cil, 1981). Water consumption of cattle increases as ambi-ent temperature increases up to 35 C, but further tempera-ture increases decrease water consumption because ofinactivity and low DMI. Similar effects as those observedunder high temperature conditions can be seen in cattle

at temperatures as low as 24 C with high humidity (Cop-pock, 1978).

Feeding MethodTotal Mixed Ration vs. IndividualIngredient

The goal of any feeding system or method is to providethe opportunity for cows to consume the amount of feedspecified in a formulated diet. Considerations in the choos-ing of a feeding system should include housing facilities,equipment necessities, herd size, labor availability, andcost. Nutrients can be effectively supplied by feeding eithera total mixed ration (TMR) or individual ingredients. ATMR allows for the mixing of all feed ingredients togetherbased on a prescribed amount of each ingredient. Whenconsumed as a TMR without sorting of ingredients, moreeven rumen fermentation and a better use of nutrientsshould occur than feeding of separate ingredients. Compu-terized or electronic feeders reduce the labor involved inindividual-concentrate feeding and provide an opportunityto control and regulate concentrate feeding to cowsthrough several small amount feedings each day. Limita-tions to feeding forages and concentrates separately arethe forages as they are usually provided free-choice andthe amount fed is usually unknown or individual cowamounts are calculated from a group average intake. Maltzet al. (1992) reported that cows fed a TMR or concentrateby computer feeders did not differ in milk production (32.7vs. 32.7 kg/d) or differ much in DMI (19.7 vs. 20.4 kg/d)during the first 20 weeks of lactation. Allocation of concen-trates through a computer feeder based on milk yield perunit of body weight was more successful in economizingon concentrate feeding without losses in milk productionand management of body weight than allocation only bymilk yield.

Feeding Frequency

It has been suggested that increasing the frequency ofoffering feed to cows increases milk production and resultsin fewer health problems. Gibson (1981) concluded in areview on feeding frequency that changing from one ortwo offerings of feed per day to four increased averagedaily gain of cattle by 16 percent and increased feed useby 19 percent. Improvements in gain or feed use weregreatest when cattle were fed high-concentrate diets. In areview of 35 experiments on feeding frequency in lactatingdairy cows, Gibson (1984) reported that increasing feedingsto four or more times per day compared to once or twiceincreased milk fat percentage by an average of 7.3 percentand milk production 2.7 percent. Higher milk fat concen-tration with increased feeding frequency also was reportedby Sniffen and Robinson (1984). The benefit of increasedfeeding frequency might be more stable and consistent

10 Nutrient Requirements of Dairy Cattle

ruminal fermentation. When Robinson and McQueen(1994) fed a basal diet two times per day and then a proteinsupplement two or five times per day, production andcomposition of milk were not affected by the frequency offeeding protein supplement, but both pH and propionateconcentration in the rumen were higher with five thanwith two feedings per day. Klusmeyer et al. (1990) reportedthat ruminal fermentation pattern and production of milkand milk components were not improved by increasingfeedings from two to four times per day. Similar resultswere found with the feeding of concentrate two or six timesper day as milk production, milk-component yield, DMI,or ruminal fermentation characteristics were not affected(Macleod et al., 1994). Fluctuations in diurnal patternsof ruminal metabolites probably have to affect microbialgrowth and fermentation adversely before a benefit ofincreasing feedings to more than two times per day willbe seen.

All of the studies reviewed for feeding frequencyinvolved the actual offering of new feed to cattle and notthe pushing in of existing feed to the manger. Whetherthe act of pushing feed in stimulates the same effects as theoffering of new feed is unknown. In the study of Macleod etal. (1994), whenever fresh concentrate was offered to thecows fed concentrate six times per day, cows fed concen-trate only twice per day would begin eating also, suggestingthe act of feeding, or maybe pushing in feed, has a stimulat-ing affect on eating.

Sequence of Feeding

Sniffen and Robinson (1984) hypothesized the followingreasons for feeding forages as the first feed offered inthe morning before concentrates. The feeding of highlyfermentable carbohydrates to cows that have been withoutfeed for over 6 hours could cause acidotic conditions in therumen depressing feed intake and fiber digestion. Feedingforage(s) as the first feed in the morning before otherfeedstuffs would allow for the formation of a fiber mat inthe rumen and provide buffering capacity in the rumenfrom both the forage and the increased salivation associatedwith forage consumption. Forages of medium to long choplength were advocated as they should prolong eating andthereby increase salivation and reduce particle passagefrom the rumen. However, evidence to support thishypothesis is lacking. In two studies (Macleod et al., 1994;Nocek, 1992) where legume forages were fed before con-centrates, no effects on rumen fermentation characteris-tics, rumen pH or milk production were found. In bothstudies, feeding forage after concentrates resulted in anumerical increase in DMI compared to feeding foragebefore concentrate.

Access to Feed

Maximal DMI can only be achieved when cows haveadequate time for eating. Data from Dado and Allen (1994)indicated early lactation cows (63 days in milk) producing23 to 44 kg of milk per day fed a TMR ad libitum ate anaverage of 5 hours per day. Feed intake occurred during9 to 13 (average of 11) eating bouts per day that averaged29 minutes per bout. Mean DMI at each eating bout wasabout 10 percent of the total daily DMI, which rangedfrom 15 to 27 kg/day. Cows in this study (Dado and Allen,1994) were housed in tie-stalls and had access to feed 22of 24 hours per day. This study demonstrates there is aconsiderable difference in eating behavior between cowsin a non-competitive feed environment and that the acces-sibility of feed must be considerably more than the 5 hoursof actual eating time per day. Martinsson (1992) and Mar-tinsson and Burstedt (1990) found that limiting the accessof feed to 8 hours a day decreased milk production of cowsaveraging about 25 kg/day by 5 to 7 percent comparedwith cows that had free-choice access to feed.

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