FEEDING MILK COWS 



471 



protein must replace fat or carbohydrates. The addition of 

 carbohydrates or fat should, in such case, increase pro- 

 duction. If there is sufficient proteids and the nitrogen- 

 free nutrients are increased, the result depends upon the 

 nutrition of the animal and the capacity of the milk 

 glands, and also upon the depression in digestion of proteids 

 caused by the additions. If the latter occurs to a great extent, a 

 decided depression in milk yield will take place, while with more 

 proteids in the ration, a less decided effect will be produced. With 

 poorly nourished but productive animals, the additions would 

 cause an increase in milk due to better nutrition, which would 

 not appear in the case of a better nourished or a less productive 

 animal. The result of the addition would therefore be different 

 according to conditions, and experiments may give contradictory 

 results. 



Both carbohydrates and fat of the feed take part in the pro- 

 duction of milk fat. For example, from an experiment of W. H. 

 Jordon, 1 we can calculate the maximum quantity of fat possible 

 to be formed from the fat fed and the proteids fed, and we know 

 from analyses the quantity of fat in the milk : 



The increase of live weight showed that the animal did not lose 

 weight. After allowing for all the fat possible from protein and 

 fat in the food, there still remains a considerable amount of fat 

 which could only come from carbohydrates. 



Increase of carbohydrates does not affect the fat in milk. Ex- 

 1 Bulletin 197, New York Geneva Station. 



