MILK PRODUCTION AND BODY INCREASE OF DAIRY COWS 33 
as measured by the calorimeter. This difference indicates the degree 
of accuracy which may be expected from metabolism experiments 
where only the respiration chamber and the bomb calorimeter are 
employed, as compared with results from the use of the respiration 
calorimeter. The presumption is that the direct measurement of 
heat production is less than the actual, and that the error involved 
in the indirect measurement of heat is therefore somewhat less than 
suggested by the foregoing figures. 
Indirectly the results from one cow seem to indicate that in the 
last stages of gestation the animal requires approximately 2 per cent 
more feed for maintenance than an animal of the same weight with- 
out a developing fetus. 
The apparent digestibility of the feed, in terms of energy, was the 
same for two of the cows, and for the third approximately 2 per cent 
higher. 
The difference in the digestibility of the feed, in terms of energy, 
when computed according to the usual method, as compared with 
the improved method, which considers all useless matter and energy 
in the light of excreta, was from 16.6 to 18.8 per cent. 
The percentage difference in heat emission for standing and lying 
as determined with cows was similar to that obtained with steers in 
earlier experiments. 
The dry matter of the feces, notwithstanding its much higher 
percentage of ash and lower percentage of ether extract, has a higher 
energy value per gram than the dry matter of the feed. 
Methane production tended conspicuously toward uniformity, and 
the average per day for the eight periods was 191.8 grams, or 267.6 
liters of CH 4 . 
During the drying of the feces to the air-dry condition there is a 
loss of about 10 per cent of the total nitrogen; hence it is necessary 
to determine nitrogen in the fresh material. 
LITERATURE CITED 
(1) U. S. Dept. of Agr., Office of Exp. Stas. Buls. Nos. 63 and 136. 
(2) U. S. Dept. of Agr., Bur. Anim. Indus. Report, 1906. 
(3) Am. Soc. Anim. Prod., Rept. of Proceedings 1922, pp. 33-46. 
(4) U. S. Dept. of Agr., Office of Exp. Stas. Bui. No. 136, pp. 146-148. 
(5) U. S. Dept. of Agr., Bur. Anim. Indus. Bui. 128, p. 113. 
(6) Proc. National Academy of Sciences, vol. 6, pp. 539-541 (1920). 
(7) Vermont Agr. Exp. Sta. Bui. No. 226, p. 182. 
(8) Kungl. Landtbruksakademiens Handlingar och Tidskrift, 1923. 
(9) Zeitschrift fur Geburtshiilfe u. Gvnakologie 52 (1904), 116. 
(10) Proc. Am. Phvsiol. Soc, Amer. Journ. Physiol. 23 (1909), p. xxxn. 
(11) Archives of Internal Medicine 7 (1911), p. 184. 
(12) Jour. Agr. Research, vol. in, No. 6, p. 467. 
(13) lll te Beretning for Forsogslaboratoriet, Copenhagen, 1923. 
