INVESTIGATIONS ON THE METABOLISM OE MILCH COWS. 911 



produced by the fasting animal performing no labor of digestion was 

 29.5 calories. Therefore 9.2 calories (3.87 — 29.5 = 9.2) represents the 

 labor per kilogram of live weight expended in digesting 28.17 gm. of 

 rice (the amount consumed per kilogram of live weight). The digest- 

 ible matter in 28.17 gm. of rice had a fuel value of 100.5 calorics 



1,568.2 



12.1 



/113 



( 71 X 4.1+ ^j— x 4.18+ 71 x 9.5 = 100.5). 



In the case of the soaked rice the labor of chewing can be left out of 

 account. The labor of digesting rice which contains practically no crude 

 liber required an expenditure of energy equal to 9.2 per cent of the 

 total energy of the digestible food. 



In the absence of more accurate data it can be said that in the case 

 of cattle crude liber yields the same amount of energy that is required 

 for its digestion. The labor of chewing and digestiug the remainder of 

 the food may be said to equal 10 per cent of the energy of the digest- 

 ible nutrients; and further, 24.1 per cent of the nitrogen-free mate- 

 rial undergoes fermentation. 



According to Kellner's calculations, a basal ration for maintenance 

 must furnish per 1,000 kg. of live weight 0.7 kg. of digestible protein, 

 and 0.0 kg. of nitrogen-free material, including 2.1 kg. of crude liber. 



In a metabolism experiment made by the writer with a milch cow, 

 the factors determined were the amount and composition of the food, 

 urine, feces, and milk, as a respiration apparatus was not available. 

 The details of the experiment were as follows: 



CALCULATION OF RESULTS' OBTAINED WITH COWS. 



During the test the cow weighed on an average 440 kg. and consumed 

 daily 5.4 kg. of wheat bran, 2 kg. of straw, 2.82 kg. of hay, 23.5 kg. of 

 fodder beets, 30 kg. of water, and 30 gm. of salt. The preliminary 

 period covered 15 days. The urine and feces were collected for 7 days. 

 On an average 13.004 kg. of urine and 25.814 kg. of feces (equal to 

 4.419 kg. of dry matter) and 9.998 kg. of milk, containing 12.1 per cent 

 of dry matter and 3.35 per cent of fat, were excreted per day. 



The amounts of nutrients iu the food and in the feces, with the coeffi- 

 cients of digestibility, are shown below: 



( ompasition of food and feces and coefficients of digestibility. 



18502— No. 10- 



