354 



NUTRITION OF FARM ANIMALS 



Both the respiration experiments and the comparative 

 slaughter tests demonstrate that the fattening of a mature 

 animal is, as its name implies, largely a production of fat, 

 which is deposited chiefly in the sub-cutaneous and internal 

 adipose tissue and to a limited extent also in the muscles. A 

 few of the comparative slaughter tests show a large storage of 

 water but the organic matter gained in every case was chiefly 

 fat. On the average of all the foregoing experiments by both 

 methods, the composition of the organic matter stored up in the 

 body of the fattening animal was as follows : - 



TABLE 67. AVERAGE COMPOSITION or ORGANIC MATTER GAINED IN 



FATTENING 



444. The gain of protein. The foregoing data also show, 

 however, that while the gain of dry matter in fattening consists 

 chiefly of fat there is also a gain of more or less protein and of 

 small amounts of mineral matter. 



The actual gain of protein in some cases was not inconsiderable. 

 This appears from Table 68, which includes both slaughter tests and 

 metabolism experiments, most of which are identical with those from 

 which the composition of the increase has been calculated. 



It is probably safe to assume that in most of these experi- 

 ments the feed contained a considerable surplus of protein 

 over that necessary for maintenance. Such a surplus of pro- 

 tein, as was shown in Chapter IX (406), has a tendency to pro- 

 duce a somewhat limited storage of protein, which probably con- 

 sists in an increase of the contents of the cells or of the protein 

 held in solution in the body fluids rather than in an increase of the 

 structural elements of the body. The observed gain, therefore, 

 may represent in part an actual increase in the cell protoplasm 

 or in the soluble protein of the body, while in addition, a rela- 

 tively small amount is accounted for by the growth of hoof, 

 horn, epidermis, etc., of the cattle and swine. Moreover, 



