MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 5 
ing feed. The work was carried on by the aid of the respiration 
calorimeter, and at some time during the last 10 days of each period, 
the animal was placed in this apparatus so that C0 2 , CH 4 , and 2 as 
well as the heat given off by the animal might be measured. 
Table 1. — Amounts of feeds and dates of periods 
Period 
Daily feed 
Dates of the periods 
Cow No. 
Hay 
Grain 
Feeding 
begun 
Calorim- 
eter test 
Collection of urine 
and feces 
631 
f I 
II 
III 
f I 
II 
I III 
{ i 
Kg. 
3.280 
3.280 
3.280 
3.364 
3.364 
3.364 
3.730 
3.730 
Kg. 
4.900 
4.900 
4.900 
5.080 
5.080 
5.080 
5.590 
5.590 
mec. 8 
fDec. 8 
jjan. 24 
[Jan. 12 
^Mar. 8 
Upr. 19 
[Feb. 9 
^Mar. 22 
iMay 3 
/Feb. 23 
\Apr. 5 
Jan. 14-22. 
Mar. 10-18. 
615... 
Apr. 21-29. 
Feb. 11-19. 
Mar. 24-Apr. 1. 
579 
May 5-13. 
Feb. 25-Mar. 4. 
Apr. 7-15. 
ANIMALS 
The subjects of this experiment were of quiet disposition and fair 
productive capacity. The choice of these particular individuals was 
determined in large part by the fact that tney were free from tuber- 
culosis, the general presence of this disease having been discovered in 
the college herd not long before the beginning of this research. After 
the conclusion of the tests here reported these cows also became tuber- 
culous, and were sacrificed before the maintenance requirements could 
be determined. The three cows were numbered 579, 615, and 631 
and are so designated throughout this bulletin. 
Cow No. 579 was a grade of seven-eighths Guernsey blood, born 
November 7, 1911. Her first calf was dropped on October 5, 1914, 
and her second on November 25, 1915. She was not bred after the 
second calving. 
Cow No. 615 was also a grade of fifteen-sixteenths Guernsey blood, 
born October 22, 1912. She aborted with her first calf May 1, 1915, 
and with her second calf (a 2-months fetus) February 20, 1916. 
Cow No. 631 was a grade Jersey, bought with age and breeding 
unknown, and supposed to have been dropped in 1906. She calved 
April 11, 1915, and was due to calve again about May 27, 1916. 
RATIONS 
All the animals were fed rations consisting of the same feeding 
stuffs mixed in the same proportions throughout the experiment. 
The quantity for each animal was adjusted so as to be sufficient at 
the outset to support milk production but not to cause any consider- 
able gain of body tissue, and remained unchanged throughout the 
experiment. It was anticipated that as the milk production decreased 
with advance in the period of lactation the surplus feed would be 
utilized for body gain in place of milk, thus affording a means of 
comparing the relative utilization of the feed for the two purposes. 
To insure complete consumption a minimum ratio of hay to grain 
was fed. The ration fed was identical with that in use at the same 
time in the dairy husbandry department of the college, the grain 
mixture being composed of wheat bran, yellow corn meal, ground 
