Energy Metabolism. Proceedings of the Eighth Symposium on Energy Metabolism Held at Churchill College, Cambridge, September, 1979 PDF
Preview Energy Metabolism. Proceedings of the Eighth Symposium on Energy Metabolism Held at Churchill College, Cambridge, September, 1979
STUDIES IN THE AGRICULTURAL AND FOOD SCIENCES Consultant Editors: D.J.A. Cole University of Nottingham W. Haresign University of Nottingham W. Henrichsmeyer Director, Institut fur Agrarpolitik, University of Bonn J.P. Hudson formerly Director, Long Ashton Research Station, University of Bristol G. Kimber Professor of Agronomy, University of Missouri-Columbia J.L. Krider Professor of Animal Sciences, Purdue University G.E. Russell Professor of Agricultural Biology, University of Newcastle-upon-Tyne D.E. Tribe Professor of Animal Nutrition, University of Melbourne V.R. Young Professor of Nutritional Biochemistry, Massachusetts Institute of Technology STUDIES IN THE AGRICULTURAL AND FOOD SCIENCES Energy Metabolism Proceedings of the Eighth Symposium on Energy Metabolism held at Churchill College, Cambridge, September, 1979 LAURENCE E. MOUNT Agricultural Research Council, Institute of Animal Physiology, Babraham, Cambridge European Association for Animal Production, EAAP Publication No. 26 BUTTERWORTHS LONDON-BOSTON Sydney - Wellington - Durban - Toronto United Kingdom Butterworth & Co (Publishers) Ltd London 8 8 Kingsway, WC2B 6AB Australia Butterworths Pty Ltd Sydney 586 Pacific Highway, Chatswood, NSW 2067 Also at Melbourne, Brisbane, Adelaide and Perth Canada Butterworth & Co (Canada) Ltd Toronto 2265 Midland Avenue, Scarborough, Ontario, M1P 3S1 New Zealand Butterworths of New Zealand Ltd Wellington T&W Young Building, 77-85 Customhouse Quay, 1, CPO Box 472 South Africa Butterworth & Co (South Africa) (Pty) Ltd Durban 152-154 Gale Street USA Butterworth (Publishers) Inc Boston 10 Tower Office Park, Woburn, Massachusetts 01801 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, including photocopying and recording, without the written permission of the copyright holder, application for which should be addressed to the Publishers. Such written permission must also be obtained before any part of this publication is stored in a retrieval system of any nature. This book is sold subject to the Standard Conditions of Sale of Net Books and may not be re-sold in the UK below the net price given by the Publishers in their current price list. First published 1980 © The several contributors named in the list of contents, 1980 ISBN 0 408 10641 7 British Library Cataloguing in Publication Data Symposium on Energy Metabolism, 8th, Cambridge, 1979 Energy metabolism. - (European Association for Animal Production. EAAP publications; no. 26). - (Studies in the agricultural and food sciences). 1. Livestock - Congresses 2. Energy metabolism - Congresses I. Title II. Mount, Laurence Edward III. Series IV. Series 636.089'2'39 SF5 80-40265 ISBN 0-408-10641-7 Typeset by Scribe Design, Chatham, Kent Printed and bound by Redwood Burn Ltd., Trowbridge & Esher The Energy Symposium dedicates this book to Grete Thorbek PREFACE This book provides a compilation of current work on the energy metabolism of animals, with emphasis on animals of agricultural importance. The chapters are written by authoritative workers in the field and are grouped in six parts. Discussions by leaders in the field deal with those topics that are of particular interest in each part. Each chapter is based on a selected paper presented at the Eighth Symposium on Energy Metabolism held at Cambridge in September 1979. The Energy Symposium is not an isolated symposium. It is an international body of research scientists that has been in existence with a continuing organization since 1958 when the first meeting was held in Copenhagen at the instigation of a number of interested workers. In connection with the origins and development of the Energy Symposium, it is a great pleasure to refer to Dr Grete Thorbek, to whom this volume is dedicated, and who was until 1979 the General Secretary. Throughout her career Dr Thorbek's name has always been strongly associated with the study of energy metabolism, and the first meeting of the Symposium that took place in Copenhagen in 1958 owed a great deal to her initiative. The succeeding meetings in The Netherlands (1961), Scotland (1964), Poland (1967), Switzerland (1970), Federal Republic of Germany (1973), France (1976) and now in Cambridge in 1979, have all benefited extensively from her continuing enthusiasm for the subject of energy metabolism, her contributions to that field of work and the very large part that she has played in the organization of meetings. She is succeeded as General Secretary by Professor K.H. Menke of Hohenheim University. In addition to Dr Thorbek (General Secretary), the Symposium Committee prior to the 1979 Symposium included K.H. Menke (Federal Republic of Germany), P.W. Moe (USA), L.E. Mount (UK), M. Vermorel (France) and D.M. Walker (Australia). The members of the Local Committee that was responsible for the organiza tion of the 1979 Symposium were G. Bull, W.H. Close, H.N. Cook, E.L. Miller and L.E. Mount (Convener), with the help during the meetings of M.F. Fuller, Maria McDonnell, Vivien Masters, Jadwiga Necel and A.J.F. Webster. vn viii Preface Each of the six topics on which the meetings were based was in the hands of its own chairman, discussion leader and two scientific secretaries: Topic No. Chairman Discussion Leadc Scientific Secretaries 1 Y. Henry A.J.H. van Es H.F. Tyrrell M. Vermorel 2 D.M. Walker K.L. Blaxter W.H. Close C. Wenk 3 P.W. Moe R.L. Baldwin L.S. Bull N.E. Smith 4 J.B. Ludvigsen H.S. Bayley M.F. Fuller J. Guillaume 5 K.H. Menke W.N. Garrett DJ. Farrell M.W.A. Verstegen 6 E.F. Annison A.J.F. Webster F. Berschauer C.W. Holmes The financial assistance that was provided by the following organizations is gratefully acknowledged: Agricultural Research Council, The British Council, European Association for Animal Production, University of Cambridge. Finally, I should like to thank Dr B.A. Cross, FRS, the Director of the Institute of Animal Physiology, for making the facilities of the Institute available to the Symposium; Butterworths, the publishers, for their help and cooperation; and Jadwiga Necel for her valuable secretarial work in the preparation of this book. Babraham, L.E. Mount Cambridge, 1979 1 ENERGY UTILIZATION BY GROWING CATTLE AS DETERMINED IN 72 COMPARATIVE SLAUGHTER EXPERIMENTS W.N. GARRETT Animal Science Department, University of California, Davis, California 95616, USA Summary Fasting heat production determined in trials involving 708 steers and 341 heifers averaged 319 ± 3 kJ/W3/4 per day (steers, 315 ± 4; heifers, 324 ± 6). The curvilinear relationships between metabolizable energy (ME; MJ/kg) and net energy values for maintenance (NE) m or for gain (NEg) were: NE = 1.373 ME - 0.0330 ME2 + 0.0006 ME3 - 4.676 m and NE = 1.415 ME - 0.0415 ME2 + 0.0007 ME3 - 6.92 g The data examined (1843 steers with hormonal implants and 861 control steers) indi cated that the energy value of the gain for cattle receiving the implant was about 4.5% lower. The energy value of gain (MJ/kg) of the British breed steers (Y=0.280 ± 0.001 W3/4 ; n=2704) was 17% lower than comparable heifers (Y=0.339 ± 0.002 W3'4; n=735) but 35% higher than a small sample of Charolais steers (Y=0.183 ± 0.005 W3*4; n=52). Introduction The comparative slaughter feeding-trial technique has been used on a routine basis for most nutritional experiments with growing cattle conducted at the University of California, Davis, since 1960. The data collected during these experiments have been made accessible for summary and computer-assisted analyses. Materials and methods The estimation of body composition using carcass density (Garrett and Hinman, 1969) provided the means to determine the energy content of the empty body of growing cattle. In all experiments an initial slaughter group established the beginning body composition. Energy retention was calculated as the difference between the estimated initial energy content and the final energy content 3 4 Energy utilization by growing cattle determined on each animal at the termination of a relatively long feeding period (100-200 days). Digestion trials were conducted on most diets fed at about 1.1 times the maintenance level. The ME values were estimated from digestible energy by the factor 0.82. Animal weight in all instances is empty body weight unless otherwise specified. The estimates of fasting heat production (FHP) were obtained by the regre ssion of log heat production/W3/4 against ME/W3/4. This approach (Garrett, Meyer and Lofgreen, 1959; Lofgreen and Garrett, 1968) was adopted for routine use of the comparative slaughter technique with cattle because of the physio logical and economic difficulties associated with keeping animals on a plane of nutrition which results in negative energy retention over long periods of time. Maintenance requirements were determined by iteration using the equation describing the relationship between heat production (HP), and ME intake, when HP = ME. The NE and the efficiency of ME use for maintenance (k ) were m m calculated from FHP and feed or ME required for maintenance. In experiments in which there were no animals fed at or near the maintenance level FHP was assumed to be 0.322 W3/4 MJ/day. The NE and the efficiency of ME use for gain (k) were determined by the g g appropriate calculation from energy retention above maintenance, feed available for gain and ME available for gain. Results and Discussion ESTIMATED FASTING HEAT PRODUCTION The information from 17 experiments with steers and nine experiments with heifers was suitable (animals fed a range of intakes from maintenance to ad lib.) for estimating the FHP by extrapolation to zero of the regression log HP/W3/4 vs ME/W3/4. The results of this analysis are shown in Table 1.1. Table 1.1 ESTIMATED FASTING HEAT PRODUCTION OF STEERS AND HEIFERS FED VARIOUS DIETS Variable No. of Regression equations- r FHP^I animals Slope ±s.e. Intercept Steers 708 0.000375 ±0.000005 2.4984 ±0.0053 0.94 315±4 Heifers 341 0.000368 ±0.000008 2.5108 ±0.0079 0.93 324 ±6 All 1049 0.000372 ±0.000004 2.5032 ±0.0044 0.94 319 ±3 a Log heat production/W3/4 (Y) vs metabolizable energy intake/W3/4(X) b kJ/day The estimates of FHP are consistent with previous determinations (Garrett, 1970; Lofgreen and Garrett, 1968) using this same technique. The difference between steers and heifers is not significant (until a level of probability of about 20%), but it may indicate that the castrated male has a very slightly lower fasting metabolic rate than the intact female. Blaxter (1962) suggested this as a possibil ity after reviewing determinations of FHP of sheep. W.N. Garrett 5 RELATIONSHIPS BETWEEN METABOLIZABLE ENERGY AND NET ENERGY The data from all animals (2766) fed at or near ad lib were used to determine the relationships between ME (MJ/kg) and NE or NE (MJ/kg) as well as k or m g m kg. The data were not uniformly distributed across the range of ME (MJ/kg) usually encountered in practical situations (1% < 8 MJ/kg; 22% > 8 MJ/kg but < 11 MJ/kg; 65% > 11 MJ/kg but < 12 MJ/kg; 12% > 12 MJ/kg). The analysis used a stepwise polynomial-regression technique to include only those variables (X to X4) that significantly improved the regression. A curvilinear relationship {Table 1.2) between ME and NE and NE accounted for approximately 2% m g more of the variation between the variables than a linear regression, but extra polation beyond the effective range of the data (ME of 9-12 MJ/kg) gave Table 1.2 RELATIONSHIPS BETWEEN METABOLIZABLE ENERGY CONCENTRATION AND NET ENERGY VALUES OR THE EFFICIENCY OF ME USE Relationship r SE ME, MJ/kg (X) 9 10 11 12 Net energy, maintenance (Y)a Curvilinear (derived) 0.92 0.40 5.49 6.49 7.38 8.17 Curvilinear (extended) (0.99)e (0.03)e 5.44 6.35 7.23 8.08 Efficiency of ME use (%), maintenance (Y')b Curvilinear (derived) 0.51 3.7 61.1 65.0 67.5 68.5 Curvilinear (extended) (0.97)e (1.6)* 59.8 63.1 65.7 67.7 Net energy, gain (Z)c Curvilinear (derived) 0.56 1.05 2.92 3.94 4.72 5.29 Curvilinear (extended) (0.99)e (0.03)e 2.96 3.78 4.55 5.29 Efficiency of ME use, gain (Z')<1 Curvilinear (derived) 0.37 9.2 32.1 39.1 43.3 44.6 Curvilinear (extended) (0.98)e (1.8)e 31.8 36.8 40.9 44.2 a Derived (n = 2766), Y = 1.27X - 0.00008X4 - 5.41; extended Y = 1.373X - 0.0330X2 + 0.0006X* - 4.676 b Derived, Y' = 17.6X - 0.72X2 - 39; extended, Y' = 12.2X - 0.619X2 + 0.0103X3 - 7.35 c Derived (n = 2766), Z' = 3.160X - 0.1130X2 - 16.36; extended Z = 1.415X - 0.0415X2 + 0.0007X3 - 6.92 d Derived (n = 2766), Z' = 33.57X - 1.40X* - 156.6; extended Z' = 18.2X - 0.90X2 + 0.0145X^-69.7 e The extended equation was estimated from averages; therefore, these values have little statistical meaning improbable values for NE and NE . In order to have some ability to predict m g NE and NE values for individual feedstuffs, whose ME concentrations were m g lower or higher than that for the mixed diets fed in these trials, an additional equation was synthesized. This extended-range equation was developed using means for NE and NE predicted from the derived equation (ME concentration m g between about 8.5 and 12.5 MJ), with NE and NE outside the range estimated m g from net-energy values calculated for individual feedstuffs with high (fat) or low (straw) concentrations of ME. The synthetic equations are, therefore, based on limited experimental data outside the ME range of 8.5—12.5 MJ/kg and need to be verified and modified when additional information is available. 6 Energy utilization by growing cattle Relationships were also developed between ME (MJ/kg) and the efficiency of ME use for maintenance (k ) or for growth (kg). The derived and 'extended' m regressions were also curvilinear. The efficiency of ME use for maintenance and for gain tended to reach near-maximum values at 15 MJ/kg ME. The data report ed by Blaxter and Boyne (1978) also show this trend. ENERGY VALUE OF WEIGHT GAIN Relationships between energy deposition and weight gains are necessary to use a net-energy system in formulating diets for specific rates of gain or to determine the rate of gain of an animal receiving a known amount of a specific feed or feed mixture. Table 1.3 is a summary of the information obtained from these data relative to the relationship between scaled energy retention and weight gain. It is immediately obvious that the scaled energy content of the gain is influenced by sex, class and breed and to a lesser extent by the use of hormonal adjuvants. Table 1.3 RELATIONSHIPS BETWEEN DAILY ENERGY GAIN (EG, Y) AND WEIGHT GAIN (X) WITH A DERIVED EXAMPLE Group No. of Equation EG, MJ/day for a 350 kg animals animal, 1.0 kg gain Observed weight basis: Steers, not implanted 861 Y=0.260 ± 0.002X (W3/4) 21.0 Implanted steers 1843 Y=0.241 ± 0.008X (W3/4) 19.5 Heifers, not implanted 405 Y=0.296 ± 0.003X (W3'4) 24.0 Implanted heifers 330 Y=0.283 ± 0.003X (W3'4) 22.9 Empty weight basis: Steers, not implanted 861 Y=0.289±0.002X(W3/4) 23.4 Implanted steers 1843 Y=0.276±0.001X(W3'4) 22.3 Heifers, not implanted 405 Y=0.348±0.003X(W3/4) 28.1 Implanted heifers 330 Y=0.332±0.003X(W3/4) 26.9 Charolais steers 52 Y=0.183±0.005X(W3/4) 14.8 These relatively simple expressions (based on the standard error of prediction) describe the data about as well as the quadratic expressions used by Lofgreen and Garrett (1968) but have the inherent implication that the energy content of the gain is independent of rate of gain for an animal of a particular size. As a generalization this may be approximately correct, but is not completely satisfying since there are reports in the literature (MAFF, DAFS and DANI, 1975; Garrett, 1978) showing that the composition of the gain is influenced by the rate of gain made over approximately the same incremental change in body weight. Further analysis of the data may result in relationships between animal weight, weight gain and energy gain which can account for the fact that rate of gain does influence the composition of the gain. Acknowledgements The contributions of Dr G.P. Lofgreen in supplying some of the data and Mr N. Hinman to the computer-assisted analyses are gratefully acknowledged.
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