2 
Journal of Agricultural Research 
Vol. XXI, No. I 
the body temperature of an animal weighing 400 kgm. is i° C. higher 
or lower than that at the beginning, it would mean, in the first case, a 
storage and, in the second case, a loss of heat by the body amounting to 
332 calories (assuming the specific heat of the body to be 0.83). Such 
a quantity would be too large to be entirely ignored in accurate deter¬ 
minations of heat production. 
It has been generally claimed that in 24- or 48-hour respiration calorim¬ 
eter experiments no serious error is introduced by the assumption that 
the body temperature is approximately the same at approximately the 
same hour of the day. It was the main purpose of this experiment to 
obtain data regarding the extent and the course of the body temperature 
variations in cattle and to study some of the factors that might influence 
them. With this object in view, observations on the body temperature 
of cows have been made with reference to the study of the following: 
1. Variations in body temperature from about 7.30 a. m. to about 5.30 
p. m., including the effect of water drunk. 
2. Thermal gradient in the body. 
3. Variations in body temperature from about 5 p. m. to about 7 p. m., 
including the effect of the feed. 
4. Effect of the act of defecation and of change in position. 
5. Daily variations in temperature measured at exactly the same time 
of the day. 
SUBJECT AND CONDITIONS OF THE EXPERIMENT 
It is essential, in order to get comparable results, that the temperature 
observations on the subject be made under as strictly uniform conditions 
as practicable. This condition of the experiment fortunately existed to 
great satisfaction, since the animals used for this experiment were those 
used at the same time at the Institute of Animal Nutrition for metabolism 
experiments with the respiration calorimeter, in which strict control of 
feeding, environment, etc., is maintained. It may perhaps not be super¬ 
fluous to give a complete description of the animals used for this experi¬ 
ment in order that a fuller appreciation of the individual variations in 
body temperature may be later had in considering the experimental 
results. 
DESCRIPTION OF THE ANIMALS 
The animals used were two dry cows, No. 885 and No. 886. They are 
both pure-bred registered Jerseys. Cow 885 was bom on March 27, 1914, 
and dropped her first and last calf on September 15, 1917. Cow 886 was 
bom on July 13, 1914, and dropped her first and last calf on October 10 
1917. They weigh about 400 kgm. each and resemble each other very 
much in respect to both size and color. 
Both cows were in good health throughout the experiment. 
