MEAT PRODUCTION 453 



No similar compilations for other species of farm animals have 

 yet been reported, although much valuable material in the 

 publications of the experiment stations awaits such discussion. 



4. INFLUENCE OF EXTERNAL CONDITIONS 



While the capacity of the animal as a meat producer and a 

 supply of feed sufficient in quantity and quality to fully utilize 

 that capacity are the two great factors in meat production, yet 

 the conditions under which the animal is kept are not without 

 influence on the results obtained. 



Temperature 



535. Teachings of practice. Since the temperature of the 

 animal body is maintained by the katabolism of materials de- 

 rived from the feed, it seemed natural to conclude that cold 

 surroundings would lead to a wasteful oxidation of feed for 

 simple heat production, and considerable emphasis has been 

 laid in the past upon the economic importance of providing 

 fairly warm quarters for live stock. At the same time, however, 

 great numbers of cattle, in particular, were being successfully 

 fattened in sheds and open feed lots and more recently a con- 

 siderable amount of experimental work has been reported show- 

 ing that this supposedly uneconomic practice actually gives 

 better returns than feeding in warm quarters. The results of 

 a considerable number of such comparisons have been sum- 

 marized by the writer 1 and leave no doubt as to the validity 

 of this conclusion, while it is entirely in harmony with the prin- 

 ciples governing the influence of external temperature upon 

 metabolism which were discussed in previous chapters. 



536. Critical temperature. As was shown in Chapter VII 

 (354), there is a certain approximate temperature, called the 

 critical temperature, at which the minimum outflow of heat 

 just balances the necessary heat production resulting from the 

 internal work and below which more or less oxidation of tissue 

 is required to maintain the normal temperature of the body. 

 Furthermore, it has been shown (395-397) that the digestion 

 and assimilation of feed and its conversion into tissue result in 



1 U. S. Dept. Agr., Bur. Anim. Indus., Bui. 108 (1908), pp. 7Q-86. 



