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a decreased particle size of the roughage in the bovine diet are proposed to decrease milk fat content.

This book can be recommended for consumers because of the dietary rec- ommendations, and for consumer groups because of the new technologies which enable the production of leaner food. This book may be interesting for those involved in advisory services on breeding, nutrition and management of farm animals. It is also recommended for research people because it offers a broad perspective of the current technologies in animal production and the needs for future research.

L.O. FIEMS National Institute for Animal Nutrition

Scheldeweg 68 9231 Melle-Gontrode

Belgium

ENERGY METABOLISM

Energy Metabolism of Farm Animals. Y. van der Honing and W.H. Close (Compilers). Proceedings of the l l t h Symposium, Lunteren, The Nether- lands, 18-24 September 1988. EAAP Publication No. 43, Centre for Agri- cultural Publishing and Documentation, Pudoc Wageningen, The Nether- lands, 1988, 414 pp., Dfl. 160, ISBN: 90-220-0951-3.

Probably the first meeting specifically on the energy metabolism of farm animals was held in 1935 at the State College, Pennsylvania, where H.P. Armsby had made his major contributions to the subject. It was organized under the auspices of the Committee on Animal Nutrition of the U.S. National Research Council, and among those present were S. Brody, N.F. Colovos, E.B. Forbes, T.S. Hamilton, M. Kleiber, L.A. Maynard, H.H. Mitchell, E.G. Ritzman and R.W. Swift. Two of these (Colovos, Kleiber ) became members of the triennial EAAP Symposia on Energy Metabolism and continued as active participants until the 1970s. It could be assumed that those engaged in such studies use and conserve energy very effectively. The first Symposium (Copenhagen, 1958) was contributed to and edited by Greta Thorbek, who has also contributed to the 11th Proceedings now being reviewed. In addition to K.L. Blaxter, A.J.H. van Es, N. McC. Graham and M. Kirchgessner, who also appear in both vol- umes, many others have contributed to nearly the whole series.

This volume is dedicated to van Es, marking his recent retirement (but not inactivity), and a special session on Past Achievements and Future Perspec- tives in Energy Metabolism was held to honour him. Among the future prob- lems mentioned by Blaxter were the need for better estimation of the energy

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values of feeds, the requirements of growing animals, and the composition of body gains, complexities resulting from genetic manipulation and the use of exogenous hormones, and the replacement of metabolizable energy as a basis for feeding systems by more objective assessments of what nutrients in what amounts and proportions are provided to the animal from its feed, and mech- anisms involved in and controlling their use. In the same session, E. Jecquier discussed energy metabolism in human obesity, and M.P.M. Vos discussed the impact of energy metabolism research on animal feeding in The Netherlands.

At the 1935 conference, H.H. Mitchell commented that "problems involved in the securing of reliable energy measurements at the present time are entirely overshadowed by those relating to the significance of the measurements ob- tained", and desired "working theories that explain or reconcile all recorded observations". Much of the first Symposium described the hardware of calor- imetry, and discussed a variety of technical principles and procedures. Subse- quent proceedings have continued to provide valuable information on such matters, as does the present volume. Thus the session on Methodology and Techniques, with 12 contributions, included a survey by P.W. Moe of new de- velopments in the measurement of energy expenditure, and three papers re- porting measurements made with the doubly labelled water technique. Human subjects were used in two of the latter, and illustrated the interesting excur- sions in the Symposia into studies on animals other than the usual 'farm' an- imals (poultry, pigs, sheep, cattle, horses); as well as a paper on rainbow trout there is one on small marsupials.

A session with 20 papers on Energy Utilization during Growth and Repro- duction was discussed by A.J.F. Webster in the context of the two fundamental questions they address: (1) how do animals make nutrient energy available for metabolism and allocate it among saleable and other products, and heat? (2) how is the allocation affected by the interaction between the diet and the ani- mal? There was a group of 19 papers on Factors Influencing Energy Expendi- ture, which included behaviour, ambient temperature, light-dark patterns, genotype, and diet composition.

In addition to methodology and observation the Symposia have increasingly been intended to 'explain and reconcile'. There were 24 papers in the session on Nutrient Partition and Energy Metabolism and 11 in the one on Modelling Energy Expenditure. The former, summarized by H.F. Tyrrell, dealt with ef- fects of the administration of exogeneous agents (beta-agonists, somatotropin, growth hormone) or the manipulation of nutrient supply on the metabolism of specific organ systems, the whole body, or both. The various measurements included protein synthesis and turnover, adipose tissue metabolism, the energy costs of ion transport, and metabolite and hormone concentrations in plasma. In discussing the models that were described, R.L. Baldwin and P.S. Miller distinguished those that would most appropriately be identified as empirical from those that were mechanistic. The equations employed in empirical models

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describe relationships among variables, but need not imply anything about underlying processes; limits of applicability are determined by the range of the information used in their construction, but they are very useful, notably in the present context in the evolution and application of feeding systems. Mecl~an- istic models are based upon an understanding of underlying cause and effect relationships and should be applicable in a wide range of conditions. They are very complex and require information on fundamental processes at the cellular level rather than at the level of, for example, input-output data across the liver.

The Symposia are a continuing record of the development of knowledge of energy metabolism and its applications. This volume, like its predecessors, should be studied by all interested in any of the many facets of the subject.

J.L. CORBETT 'Harlaw '

Donald Road Armidale, N.S. W. 2350

Australia

R U M I N A N T N U T R I T I O N

Recent Developments in Ruminant Nutrition 2. W. Haresign and D.J.A. Cole (Editors). Butterworths, 1988, Paperback, 387 pp., tables, figs., £17.50, ISBN: 0-407-01164-1.

This volume is the second in a series; the first volume was published in 1981. The present volume is a selection of chapters from Recent Advances in Nutri- tion, which represents the Proceedings of the University of Nott ingham Feed Manufacturers. Twelve of the 22 articles were published in the proceedings prior to 1985. The reader should be aware that these 12 articles may not con- tain some of the most recent information in the subject area presented. Never- theless, they are very comprehensive and contain extremely useful information that both the researcher and the producer can make use of in their area of interest. Space does not permit each of the 22 chapters to be discussed in detail, only by general subject area. Several chapters deal with various aspects of milk production, such as dietary concentrate level, fiber, dietary fat, silage, manip- ulation of milk composition and protein utilization. Feed intake is discussed in several areas as related to dietary formulation, ration components and per- formance. There is considerable discussion of ruminal degradable and nonde- gradable protein as related to differences in feeding management for the dairy cow, particularly in early lactation. Someof the factors important in this con- cept are roughage level and types, and rapidly degradable protein supply and type. To date there is no general agreement on a new system to take these factors into account because of the complex aspects of ruminant protein me- tabolism. The nutrient requirements of intensively raised beef cattle is dis-