14 UNIV. OF N. H. AGR. EXPERIMENT STATION [Bulletin 232 



energy production between different individuals and between different 

 species. 



Under as nearly comparable conditions as it was possible to obtain to 

 those of non-ruminants, the basal heat production of steers was found to 

 be 1,300 calories every twenty-four hours per square meter of body 

 surface, or more than twice that (600 calories) found in the white rat and 

 much in excess of that found in humans (925 calories for men and 850 

 calories for women). 



In this relatively small group of warm-blooded animals, therefore, — the 

 man, the steer, and the rat, — there is a variability ranging from 600 to 

 1,300 calories per twenty-four hours. The heat production of the steer 

 under conditions comparable with man is fully 40 per cent greater. Thus, 

 the laws governing heat production and heat loss may be very different 

 with different types of animals. Indeed, it is possible that the two proc- 

 esses are to a considerable extent independent of each other. 



Other Observations on Fasting 



With ruminants the food residues in the intestinal tract are very large, 

 amounting at times, in the case of the steer, to one-fifth of the entire body 

 weight. The possibility of these residues serving as a source of energy 

 for a considerable period has long been assumed. 



The studies in the respiration chamber, however, have definitely shown 

 that live weight losses are no indication of real tissue changes. Nitrogen 

 losses indicate drafts upon body protein; but for sustaining the life proc- 

 esses during fasting, by far the largest draft upon the body stores is made 

 upon fat. With steers the experiments showed a distinct tendency for 

 the fat to fall off rather rapidly during the first one or two days of fasting. 

 As fasting continues, however, the heat or energy production continually 

 and regularly declines. 



The general behavior of fasting steers leads to the deduction that the 

 so-called "hunger feeling" is merely the temporary sensation caused by 

 physical contraction of the alimentary tract to meet requirements of a 

 diminished bulk. In no sense does it represent distress due to lack of 

 nourishment of tissues. After the second day no particular irritation or 

 craving for food was manifested. 



Equipment and Technique 



Noteworthy changes and improvements in equipment and technique 

 have been made in gas analysis. With the new apparatus now installed 

 the capacity of the operator in determinations of carbon dioxide, oxygen, 

 and methane gas has been trebled. 



A small respiration chamber for individual sheep has also been installed 

 to supplement some of the earlier work done in groups on sheep. 



This apparatus is designed entirely on new lines and, if successful, will 

 simplify materially the problem of indirect calorimetry. (Adams Fund.) 



