438 PRINCIPLES OF ANIMAL NUTRITION. 
Een 
Live Weight, | per 100 Pounds, 
Lbs. 
Winter (temp. about 40° F.) .... { eae bee 
Summer(“ = “80° F.) | “ee ae 
On the other hand, Cooke,* in a series of experiments on swine 
at the Colorado Station, found the following amounts of computed 
digestible matter required for maintenance per hundred pounds live 
weight of animals weighing from 85 to 182 pounds per head: 
In hot weather............. ccc cece eee 0.93 Ibs. 
In moderate weather..............ce000 1.25 “ 
In cold weather............0c cece ee eeees 1.41 “ 
Consumption of Water.—A not inconsiderable amount of energy 
is usually required to raise the ingesta to the temperature of the 
body. This is particularly true of the water consumed, especially 
in case of the herbivora, both by reason of its relatively large amount 
as compared with the dry matter of the food and on account of its 
high specific heat. At first thought it might seem that the warming 
of the ingesta is part of the work of digestion, since it is an expendi- 
ture of energy in preparing the food for assimilation. This same 
matter or its equivalent, however, finally leaves the body, in the 
form of various excreta, at body temperature, thus carrying off as 
sensible heat substantially the same amount of energy which was 
imparted to it when its temperature was raised, and this heat it 
imparts in cooling to the environment of the animal. It would 
seem, then, that the warming of the ingesta may be more logically 
regarded as a part of the general draft for heat which the surround- 
ings make upon the animal, the process being simply a little less 
direct than the loss of heat by radiation and conduction through 
the skin. 
From this point of view the influence of the consumption of cold 
food and particularly of cold water will be subject to the same 
general laws as the other forms of the demand for heat. On a 
ration supplying less than the critical amount of metabolizable 
* Private communication. 
