Mar. as. 191S Energy Values of Feeding Stuffs for Cattle 459 



RELATION TO AMOUNT OF FEED 



In spite of the considerable variations in the individual results and of 

 some negative values,. it appears clear, both from Table VII and from fig- 

 ure I, especially if the comparisons be made between the smallest and the 

 greatest rations, that the effect of the feed in increasing the metaboUsm 

 tended to be distinctly greater during standing than during lying, and 

 that, on the whole, the differences tended to be greater with concentrates 

 or with mixed rations than with coarse feeds. In other words, the differ- 

 ence between the metabolism of the animal when standing and when 

 lying was relatively greater on the heavier than on the lighter rations. 



This difference can hardly be ascribed to a greater direct stimulus of 

 cell metabolism by the products of digestion. One explanation for it 

 might be sought in the fact that the feed was consumed by the animal 

 while standing. Experiments by Paechtner (39) and by Dahm (17) on 

 cattle and by Ustjanzew (46) on sheep, in which the respiratory exchange 

 was determined in short periods, showed that the mastication of i kg. 

 of hay increased the metabolism of the animal by approximately 60 

 Calories. In our experiments this would be equivalent to the production 

 during perhaps half an hour after feeding — i. e., at 6 a. m. and 6 p. m. — 

 of from 12 to as much as 200 Calories of heat, or twice this amount in 24 

 hours, which amounts would be added to the standing metabolism. On 

 the other hand, however, according to the same experimenters, the 

 rumination of the feed would increase the heat production by, roughly, 

 two-thirds as much, and this would constitute to a considerable extent 

 an addition to the metabolism of the animal when lying, thus partially 

 but not wholly compensating for the addition to the metabolism when 

 standing consequent on mastication. 



It would appear, then, that the mastication of the heavier rations would 

 tend to increase the ratio of heat production of the animal when standing 

 to that when lying. The heat elimination, however, in our experiments 

 showed no distinct evidence of such an increase. The rate of heat emis- 

 sion per minute while the feed was being eaten showed infrequently a 

 slight rise, which was seldom sharp and which was far less than would 

 correspond to the presumable increase in the gaseous exchange. In 

 many instances no effect upon the heat elimination was observed, but 

 rather frequently there was a distinct fall. Sometimes, although not in 

 the majority of cases, a rise was observed after the animal had finished 

 eating. The animal was watered after the 6 a. m. feeding. Sometimes 

 no perceptible change in the rate of heat emission resulted, but not infre- 

 quently a fall was observed, which was occasionally considerable. It can 

 hardly be doubted that there must have been an increased production of 

 heat during mastication, but apparently this heat was not given off 

 promptly. Part of it at least, it may be conjectured, was applied to warm 



