Mar. 25. 191S Energy Valiies of Feeding Stuffs for Cattle 



475 



Table X. — Increments of heat production per kilogram of dry matter — Continued 



CRITIC.\I, TEMPERATURE 



In order that comparisons like the foregoing shall be valid, the experi- 

 ments must, of course, be made above the so-called ''critical tempera- 

 ture" for the animal experimented with and for the minimum quantity 

 of feed consumed, since below this temperature part of the heat produced 

 is utilized to maintain the body temperature and thus to reduce the 

 amount of heat liberated by the katabolism of body substance (2, p. 

 347-359, 407-410). Our experiments have been made at about 17° to 

 18° C, and we have not attempted to determine the critical temperature 

 for cattle, but the fact clearly shown in figure 2 that the heat production 

 per kilogram of feed consumed showed no tendency to increase as the 

 rations were made heavier leads us to believe that even on the lightest 

 rations the temperature was safely above the point at which the so-called 

 "chemical" regulation of body temperature begins. Kellner's experi- 

 ments were made at somewhat lower temperatures, mostly between 12° 

 and 15° C, but on heavier rations. 



