MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 
23 
Thus, for example, starting with the assumption that the energy 
of the feed minus the energy of the excreta equals the metabolizable 
energy then with an animal in nutritive equilibrium the total heat 
production (Table 19) equals the metabolizable energy. In case 
the animal gains body tissue the energy of the excreta is thereby 
lowered, the metabolizable energy is greater than the total heat 
production, and in computing the heat production, a correction for 
the chemical energy of the body gain must be subtracted from the 
metabolizable. Should the animal lose body tissue, then the heat 
production and the energy of the excreta are thereby increased by 
the energy equivalent of the tissue lost, and in computing the heat 
production the chemical energy of the body loss must be added to the 
metabolizable. 
It may be assumed that in the case of a cow receiving sufficient 
energy in her feed for maintenance, and also to supply the greater 
portion of the energy of the milk, any loss of body tissue goes to 
support the milk production, and that therefore the energy of this 
loss has been transferred to the milk. This transformation of body 
tissue into milk involves but a small loss of energy. Since the 
amount of this loss is not known to the writers, it has been omitted 
in the computation. Desiring at this time only to compare the total 
heat production as measured with the computed heat production, 
the heat of fermentation has also been ignored. 
The computed heat production per day and head has been calcu- 
lated in accordance with the foregoing methods and the results given 
in Table 19. 
Table 19.— 
Computed heat production (indirect calorimetry) 
Period I 
Period II 
Period III 
Intake 
Outgo 
Intake 
Outgo 
Intake 
Outgo 
Cow 631: 
Feed 
Calories 
32, 462. 6 
Calories 
Calories 
32, 364. 
Calories 
Calories 
32, 191. 6 
Calories 
10, 820. 6 
1, 583. 8 
2, 628. 
110.1 
5, 378. 2 
11,026.0 
1,691.1 
2, 522. 5 
78.3 
784. 1 
10, 702. 9 
1,431.7 
2, 419. 5 
93.7 
Milk 
136.8 
205.2 
660. 1 
Body fat 
358.2 
11, 720. 5 
3, 868. 4 
12, 598. 8 
3, 203. 4 
13, 680. 3 
Total . 
32, 599. 4 
32, 599. 4 
32, 569. 2 
32, 569. 2 
32, 191. 6 
32, 191. 6 
Cow 615: 
Feed . . 
33, 511. 3 
33, 407. 8 
33, 332. 3 
11, 397. 3 
1, 323. 4 
2, 404. 6 
107.5 
6, 020. 
116.3 
385.7 
11, 756. 5 
11, 076. 7 
1, 409. 2 
2, 420. 1 
97.6 
6, 278. 7 
11, 125.3 
1, 406. 3 
2, 457. 3 
89.1 
Milk . 
6, 157. 
41.0 
119.7 
242.8 
407.5 
Body fat 
12, 286. 2 
12, 747. 6 
Total 
33, 511. 3 
33, 511. 3 
33, 568. 5 
33, 568. 5 
33, 982. 6 
33, 982. 6 
Cow 579: 
Feed 
36, 762. 6 
36, 791. 4 
Feces 
11, 459. 
1, 487. 2 
2, 792. 
70.2 
7, 023. 6 
324.9 
59.8 
13, 545. 9 
11, 655. 5 
1,611.3 
2, 835. 2 
87.7 
6, 749. 5 
61.6 
625.1 
13, 165. 5 
Urine (uncorrected)... . . 
Methane.. 
Brushings 
Milk 
Body protein 
Body fat 
Balance 
Total 
36, 762. 6 
36, 762. 6 
36, 791. 4 
36, 791. 4 
