206 



NUTRITION OF FARM ANIMALS 



be subtracted from the total gain of carbon, the remainder 

 can have been gained only in the form of fat and the corre-. 

 spending amount of this substance can be readily computed. 



294. Example of a carbon balance. In a respiration experi- 

 ment on a steer a complete statement of the nitrogen and carbon 

 balances is as follows : 



TABLE 23. NITROGEN AND CARBON BALANCES OF A STEER 



The nitrogen balance shows that the animal gained n.i X 6.0 = 

 66.6 grams of protein. According to Kohler's results (88), the 

 average protein of cattle contains 52.54 per cent of carbon. Conse- 

 quently, the protein gained in this experiment contained 66.6 X -5254 

 = 35.0 grams of carbon. The total gain of carbon, however, as 

 shown by the carbon balance, was more than this, viz., 46.6 grams, and 

 we accordingly have the following : 



Total gain of carbon 46.6 grams 



Carbon in protein gained . . . 35.0 grams 

 Carbon gained as fat .... 1 1.6 grams 



The elementary composition of animal fat was shown in Chapter 

 I (34) to be very uniform, averaging 76.5 per cent of carbon. A 

 gain of 0.765 gram of carbon in the form of fat, therefore, is equiva- 

 lent to a gain of one gram of fat or a gain of one gram of carbon to 

 1.31 grams of fat, and accordingly the gain of n.6 grams of carbon 

 in the form of fat shows a gain by the animal of n.6 -f- 0.765, or 

 11.6 X 1.31 = 15.2 grams of fat. Substantially the same method of 



