404 



NUTRITION OF FARM ANIMALS 



growing animals, there are a considerable number of experi- 

 ments, especially upon immature fattening animals, in which 

 the increase of live weight has been determined upon rations 

 otherwise reasonably similar but containing varying propor- 

 tions of protein. 



In the immature fattening animal, it seems safe to assume that the 

 feed protein (in excess of maintenance) is applied substantially to the 

 support of growth and that this growth goes on parallel with the 

 fattening process but more or less independent of it. There appears 

 to be no evidence that protein specifically stimulates or aids fatten- 

 ing, so that conclusions regarding the protein supply drawn from 

 fattening experiments may be regarded as applicable to growth without 

 fattening. 



If in such an experiment, in which the total amounts of feed 

 consumed do not differ widely, it appears that the smaller 

 amount of protein has been as efficient as the larger as regards 

 gain in live weight, and if the gain appears to be normal in 

 amount, there is a strong presumption that the lesser amount 

 of protein was at least sufficient for the needs of the animal for 

 growth and maintenance, while if a block test shows a normal 

 character of increase this presumption is further strengthened. 

 Obviously, results of this sort cannot be relied on to fix definitely 

 the lower limit of protein supply, but they may furnish indica- 

 tions regarding it. 



486. Experiments with cattle. In the experiments upon 

 calves by Soxhlet, De Vries Jzn and Neumann, included in 

 Table 80 (463), showing the rate of gain of protein, the amounts 

 of digestible protein consumed as compared with the actual 

 gains were as follows : 



TABLE 95. PROTEIN CONSUMED BY CALVES 



