MILK PRODUCTION 



505 



have been grouped according to the amount of this surplus, and 

 the average percentage increase in the yield of milk solids and 

 of milk fat which resulted from an increase of the feed protein 

 has been computed for each group. 



TABLE 140. INFLUENCE OF PROTEIN SUPPLY ON MILK PRODUCTION 



On the whole, Morgen's investigations seem to furnish con- 

 clusive evidence of a stimulating effect of protein on milk pro- 

 duction. Even when the protein supply already largely exceeded 

 the minimum demand, a further addition was in most instances 

 followed by a distinct increase in the yield of milk solids and 

 usually in that of milk fat. It should be said, however, that a 

 respectable minority of the individual experiments failed to 

 show this effect. Of the nineteen single trials in which protein 

 was substituted for fat, eleven showed an increased yield of 

 milk solids and six an increased yield of milk fat. Out of the 



1 Digestible protein minus requirements for maintenance and for growth of wool. 



