318 The Feeding of Animals 



soon a return to the animal's normal product. In a 

 small proportion of experiments, the milk appeared to 

 sustain a permanent though not extensive modification. 

 The weight of testimon}^ bears out the statement that 

 the quality of milk cannot be changed at will by the 

 farmer, but is largely determined by causes not under 

 his control, such as breed and individuality, although 

 feeding and treatment, especially the latter, have more 

 or less influence upon the character of the milk secreted. 

 It is possible, even probable, that continuous feeding 

 either very poorly or very highly may bring about in 

 time a permanent change in a cow's milk, but to-day 

 no one is wise enough to point out a way of definitely 

 controlling this product through the food. 



{!)) In the discussions relative to feeding dairy cows, 

 another point has received much attention; viz., the 

 effect of foods upon the proportions of the constitu- 

 ents which make up the dry matter of milk. A popu- 

 lar notion has prevailed that it is possible to "feed 

 fat into milk," having its origin in part, perhaps, in 

 misconceptions as to the manner of milk formation. 

 If the mammary gland served simply to capture the 

 unchanged constituents of the food, then it might be 

 reasonable to expect the milk to partake of the char- 

 acter of the digested nutrients and be "fat" or "lean" 

 according to the proportions of proteids and fats sup- 

 plied to the animal. When, however, we consider that 

 this gland has the function of transforming the raw 

 material of the food into a milk which is characteris- 

 tic of the breed or of the individual in accordance with 

 somewhat fixed constitutional limitations, and that from 



