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Ruminant Nitrogen Usage Subcommittee on Nitrogen Usage in Ruminants Committee on An mat Nutrition Board on Agriculture National Research Council NATIONAL ACADEMY PRESS Washington' D.C. 1985
National Academy Press · 2101 Constitution Avenue, NW · Washington, DC 20418 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Researeh Council, whose members are drawn from the councils of the National Aeademy of Seienees, the National Aeademy of Engineering, and the Institute of Medieine. The members of the committee responsi- ble for the report were chosen for their special eompetences and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Acad- emy of Engineering, and the Institute of Medieine. The National Research Couneil was established by the National Aeademy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and of advising the federal government. The Council operates in accordance with general policies determined by the Aeademy under the authority of its congressional charter of 1863, which establishes the Academy as a private, nonprofit, self-governing membership corporation. The Couneil has become the principal operat- ing agency of both the National Aeademy of Sciences and the National Aeademy of Engineering in the conduct of their services to the government, the public, and the scientific and engineering communities. It is administered jointly by both Academies and the Institute of Medicine. The National Aeademy of Engineer- ing and the Institute of Medieine were established in 1964 and 1970, respectively, under the charter of the National Academy of Sciences. This study was supported by the Agricultural Researeh Service of the U.S. Department of Agriculture, by the Center for Veterinary Medicine, Food and Drug Administration of the U.S. Department of Health and Human Services, and by the American Feed Industry Association, Ine. Library of Congress Cataloging in Publication Data National Researeh Couneil (U.S.) Subcommittee on Nitrogen Usage in Ruminants. Ruminant nitrogen usage. Bibliography: p. Includes index. 1. Nitrogen in animal nutrition. 2. Ruminants- Feeding and feeds. I. Title. SF98.NSN37 1985 636.2'08'52 85-21682 ISBN 0-309-03597-X Copyright (D 1985 by the National Academy of Sciences No part of this book may be reproduced by any mechanical, photographic, or electronic process, or in the form of a phonographic recording, nor may it be stored in a retrieval system, transmitted, or otherwise copied for public or private use, without written permission from the publisher, except for purposes of offi- cial use by the United States government. First Pnnung, October 1985 Second Panting, December 1991 Printed in the United States of America
Preface The Subcommittee on Nitrogen Usage in Ruminants of the Committee on Animal Nutrition was instructed to address the increasingly apparent need to bring together the newer data and knowledge on ruminant nitrogen metabolism in such a way that a systematic, quantita- tive approach to the rationing of ruminants for nitrogen could be set forth. The charge to the Subcommittee included the need to produce a report that could be used by producers, tech- nical service people in the feed ant] related industries, as well as extension personnel, teachers, students, and research scientists. The document was to serve as a base, upon which future refinement could be built, in such a way that continual improvement would occur. Whereas many countries around the world have pro- posed nitrogen or protein systems for ruminants, this ef- fort was to evaluate each of those and incorporate those biological principles that are common to all ruminants. During the course of the Liberations of this subcom- mittee, invaluable help has been provided by the staff of the Board on Agriculture, especially Selma P. Baron and Philip Ross. This has been a most complex task, and without the encouragement and assistance of these peo- ple, the document contained herein would not have emerged. We especially appreciate the efforts of Werner G. Bergen who reviewed this report for the Committee on Animal Nutrition and provided useful information for consideration by the authoring subcommittee. Also, the encouragement of Joseph P. Fontenot and Robert R. Oltjen has been greatly appreciated; the former also served as the reviewer for the Board on Agriculture. As a result, we fee! that we have produced a document that meets the stated objectives of the original charge. The assistance of Zaira Batchelder, Alice Jones, and Elaine Wylie in the preparation of drafts and manuscripts is gratefully acknowledged. Subcommittee on Nitrogen Usage in Ruminants LEONARD S. BULL, Chairman University of Vermont WILLIAM CHALUPA University of Pennsylvania FREDRIC N. OWENS Oklahoma State University LARRY D. SATTER USDA, Dairy Forage Research Center CHARLES J. SNIFFEN Cornell University ALLEN H. TRENKLE Iowa State University DALE R. WALDO USDA, Agricultural Research Service · - ~ 111
COMMITTEE ON ANIMAL NUTRITION DUANE E. ULLREY, Chairman, Michigan State University FRANK AHERNE, University of Alberta RICHARD E. AUSTIC, Cornell (Jniversity JIMMY H. CLARK, University of Illinois RICHARD D. GOODRICH, University of Minnesota GEORGE E. MITCHELL, JR., University of Kentucky JAMES G. MORRIS, University of California-Davis ROBERT R. SMITH, USDI, Fish and Wildlife Service DALE R. WALDO, USDA, Agricultural Research ~ . service SELMA P. BARON, Staff Officer BOARD ON AGRICULTURE WILLIAM L. BROWN, Pioneer Hi-Bred International, Inc., Chairman JOHN A. PING, Inter-American Development Bank, Vice Chairman PERRY L. ADKISSON, Texas A&M University C. EUGENE ALLEN, University of Minnesota LAWRENCE BOGORAD, Harvard University ERIC L. ELLWOOD, North Carolina State University JOSEPH P. FONTENOT, Virginia Polytechnic Institute and State University RALPH W. F. HARDY, Cornell University and BioTechnica International, Inc. ROGER L. MITCHELL, University of Missouri CHARLES C. MUSCOPLAT, Molecular Genetics, Inc. ELDOR A. PAUL, University of California-Berkeley VERNON W. RUTTAN, University of Minnesota JAMES G. TEER, Welder Wildlife Foundation JAN VAN SCHILFGAARDE, USDA, Agricultural Research Service VIRGINIA WALBOT, Stanford University CHARLES M. BENBROOK, Executive Director 1V
Contents Introduction Parameter Names for Describing Protein Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 . Comparison of New Protein Systems for Ruminants Feed Evaluation 7 .23 Degradation of Dietary Crude Protein in the Reticulo-Rumen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28 Microbial Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37 Digestion and Absorotion in the Small Intestine ~- 46 Nitrogen Metabolism in the Large Intestine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53 Nitrogen Metabolism in Tissues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57 Application to Ruminant Feeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~ Appendix Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87 Index v
Figures, Tables, and Appendix Tables FIGURES 1. Schematic of nitrogen flow in the ruminant, 2 2. Schematic diagram of nitrogen flow in the ruminant using symbols developed in this publication, 3 3. Intake protein percentage in dry matter as a function of milk production, 17 4. Undegradability of dietary intake protein as a function of milk production, 18 5. Undegradability of dietary intake protein as a function of intake protein percentage in dry matter, 18 6. Protein flow into small intestine predicted from the system versus that expected based on the digestible organic matter of the system and the equation of Tamminga and van Hellemond (1977), 19 7. Protein flow into small intestine predicted from the system versus that expected based on the digestible organic matter of the system and the equation of Rohr et al. (1979), etc., 19 8. Protein flow into small intestine predicted from the system versus that expected based on the digestible organic matter plus undegraded protein intake of the system and the equation of Journet and V`erite (1979), 20 9. Fecal protein as a function of intake protein percentage in dry matter, 20 10. Fecal protein as a function of milk production, 21 11. Urinary protein as a function of milk production, 21 12. Milk protein as a function of milk production, 22 13. Simplified model showing flow of amino acids in mammalian metabolism, 58 TABLES 1. Assumed Factors in the Availability of Absorbed Protein to Ruminants, 9 2. Assumed Factors in the Requirement of Absorbed Protein by Ruminants for Maintenance, Milk Production, and Body Weight Change, 10 3. Dry Matter Intakes and Energy Standards When Energy Concentration Varied as Used in Comparison and Challenge of Protein Systems, 16 4. Additional Assumptions of Protein and Energy Relationships, 17 5. Interrelationship Among In Vivo Responses, Undegradability Assays, and Insolubility Assays, 24 6. Tentative Estimates of Undegraded Protein for Common Feedstuffs When Total Dry Matter Intake is in Excess of 2 Percent of Body Weight, 33 7. Composition of Microbial Cells, 38 8. Regressions for Dairy Cattle, Sheep, and Beef Cattle, 42 Vl
Figures, Tables, and Appendix Tables vii 9. Empirical Prediction Models of Microbial Nitrogen Flow, 44 10. Equations Used for Predicting Microbial Yield or Efficiency, 45 11. Summary of Apparent Absorption of Nonammonia Nitrogen ant] Amino Acids from the Small Intestine of Ruminants, 47 12. Proportionate Disappearance of Amino Acids from the Small Intestine, 48 13. Supplies of Nonammonia Nitrogen and Amino Acids to the Proximal Duodenum and Ter- minal Ileum, Apparent and True Digestibility of Nitrogen, and Endogenous Loss of Nitro- gen to the Small Intestine, 49 14. Summary of True Absorption from the Small Intestine, 50 15. Estimates of True Digestibility and Metabolic Fecal Nitrogen, 54 16. Extraction of Amino Acids by Various Tissues, 58 17. Estimated New Protein Requirements for Growth of Cattle of Different Body Weights and Gaining at Different Rates, 64 18. Protein Retention in Gain of Growing Sheep, 64 19. Protein Retention in Fetus and Gravid Uterus of Cattle at Different Stages of Gestation, 64 20. Protein Retention in Fetus and Gravid Uterus of Sheep at Different Stages of Gestation, 65 21. Protein Content of Milk, 65 APPENDIX TABLES 1. Numerical Data from the Protein Systems Used in Figures 3 Through 12, 89 2. In Vivo Estimates of the Percentage of Undegraded Protein in Common Feedstuffs, 90 3. Microbial Flow and Rumen Organic Matter Digestion, 98 4. Urea Usefulness with Various Feed Intakes, TDN Levels, and Ruminal Digestions of Dietary Protein Based on Equations from Dairy Cattle, 108 5. Urea Usefulness with Various Feed Intakes, TDN Levels, and Ruminal Digestions of Dietary Protein Based on Equations from Beef Cattle, 109 6 Urea Usefulness with Various Feed Intakes, TDN Levels, and Ruminal Digestions of Dietary Protein Based on Equations from Sheep, 109 7. Production of Microbial Protein and Escape Protein Requirements for Beef Cattle of Various Weights and Types, 110 8. Requirements of Total and Escape Protein for Beef Cattle of Various Types, Weights, and Rates of Gain, 111 9. Factors Adopted for Transforming Feed Protein into Net Protein for Dairy Cattle, 113 10. Factors Adopted for Transforming Feed Protein into Net Protein for Beef Cattle, 123 11. Apparent Absorption of Nitrogen from the Small Intestine of Lactating Cattle, 135 12. Apparent Absorption of Nitrogen from the Small Intestine of Nonlactating Cattle, 135 13. Apparent Absorption of Nitrogen from the Small Intestine of Sheep, 136
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