1911.] 



PUBLIC DOCUMENT — No. 31. 



119 



Influence of Protein on Milk Shrinkage {Average Itcsults). 



The average amount of digestible protein consnmed daily 

 by each of the high-protein cows (1.83 jxmnds) was not qnite 

 as high as intended, hence the difference between the low and 

 high protein rations was not particularly pronounced. Never- 

 theless, one would expect if the conditions were reasonably 

 satisfactory that the low-protein cows would have shrunk in 

 their milk yield (over an average of two hundred days) rather 

 more than the high-protein cows. Such, however, was not the 

 case, the shrinkage of both herds being substantially identical. 

 The only explanation that can be offered is the undue influence 

 of individuality and the small number of cows in each group. 

 For example, Mary shrunk 49 per cent, during the experiment, 

 it being characteristic of this animal to dry off quite rapidly 

 after she had been four months with calf; Daisy also had 

 such a tendency. The individuality of each animal, as well 

 as its age and condition, all have a pronounced influence, 

 especially when the experiment is extended over a long period 

 of time, and in order to arrive at the truth a large number of 

 animals must be used with as near similar conditions as it 

 is possible to secure. Is it probable that if an animal receives 

 sufficient protein to supply the daily demands of her body 

 (maintenance) and of the milk produced, she will not shrink 

 in her yield during a milking 'period any more than when she 

 is receiving 25 to 50 per cent, protein in excess of the actual re- 

 quirements ? In other words, is it not possible that the excess 

 protein acts as a stimulus for a time, after which the in- 

 dividuality of the animal becomes the more pronounced factor ? 



