350 
Journal of Agricultural Research 
Vol. XXI, No. s 
namely, somewhat above the critical point, but not so much as to affect 
the appetite and thrift. These limits, evidently, will vary with the 
species of animal and with the amount and character of the ration. The 
best temperature surroundings for animals being fed high, according to 
King, are likely to lie between 45 ° and 50° F., while for animals on a 
maintenance ration, the best temperatures may be between 55 0 and 65°. 
For dairy cows having large udders only scantily clothed with hair and 
through which much blood must flow, a temperature as high as 50° to 
6o° is considered as probably the best. 
Whether the heat eliminated by animals is sufficient to maintain in 
the stable approximately these temperatures in cold weather when the 
air movement is at the proper rate will be considered on subsequent 
pages. 
METHOD OF COMPUTING HEAT PRODUCTION 
The discussions of the foregoing paragraphs make it evident that the 
heat produced by an animal may be regarded as the sum of two factors, 
first the necessary internal work due to the vital activities of the internal 
organs and, second, the “work of digestion." The first gives rise to an 
amount of heat equivalent to the fasting katabolism, which varies with 
the species and size of the animal, while the second gives rise to an incre¬ 
ment of heat due to feed consumption, which varies with the character 
and quantity of the ration. It is clear, then, that no single standard 
value can be assumed as representing even approximately the heat pro¬ 
duction of any species. 
When the fasting katabolism of an animal and the heat increment 
due to the feed eaten are known, it is evident that the total heat produced 
by the animal can be computed by simple addition. Experimental data 
are available from which it is possible to estimate more or less accu¬ 
rately the fasting katabolism of farm animals according to their live 
weights, and also the increment of heat due to the ration feed. These 
data have been used as the general basis for computing the heat produc¬ 
tion. The details of the method are best illustrated by the computation 
on subsequent pages of the heat production of dairy cows. 
ACCURACY OF THE COMPUTATIONS 
The reader should beware of being led by the apparently very exact 
figures of the tables on succeeding pages to ascribe to these data a greater 
degree of accuracy than they really possess. 
In the first place they represent specific cases assumed to be more or 
less typical. The actual production of heat, carbon dioxid, and water by 
a given species will show wide variations from stable to stable, and in 
the same stable from time to time, according to the size of the 
animals, their degree of activity, and especially the amounts of feed 
which they consume. 
