ShekHy — The Infhience of Feeding on Milk Fat. 'ISt 



incieases the butter fat, a further similar addition does not increase the 

 butter fat to the same extent. In goal 1, the addition of half a pound of 

 fat to the ration (ration E to F) increased the milk fat by 0'05 lb. ; a further 

 addition of half a pound caused an increase of only 0-025 lb. milk fat. Even 

 where the diet already contains a large proportion of protein (ration F, 

 goat 3) the further addition of half a pound of fat to the diet gave an increase 

 of only 0'025 lb. milk fat. The percentage of fat in milk can obviously be 

 raised by extra feeding to a maximum ; aud, if fat percentage is the only 

 consideration, it might be said that the maximum is reached according to the 

 \aM of diminishing returns. But, as the ration is increased, body weight 

 and total milk may be also increased, and a successively larger proportion of 

 the food utilized for these purposes. Since, according to Nils Hansson [1916] 

 and Wilson [1920], the law of diminishing returns does not hold in the 

 production of beef and milk, neither is it likely to hold in the production 

 of butter fat. 



Summary. 



In the case of a lactating goat — 



1. A considerable reduction in the ration may cause a decrease in the 

 percentage of fat in the milk. This occurs when the total fat yield is de- 

 creased at the same time as the milk yield remains unchanged, or when the 

 proportionate decrease in the total fat is greater than the decrease in milk. 



2. The addition of a concentrate to a ration may cause an increase in the 

 percentage of fat in milk. This occurs when the total fat yield is increased, 

 while the milk yield remains unchanged, or when the proportionate increase 

 of total fat is greater than the increase in milk. 



3. In effecting an increase in the total and in the percentage of butter fat 

 in milk, starch, fat (soya and butter), and protein can replace one another. 

 After the necessary minimum of protein is supplied, starch and casein replace 

 one another for that purpose in equal parts. 



4. There is a maximum milk fat percentage, and, as this limit is 

 approached, the extra food added to the ration produces a successively 

 decreasing addition to the milk fat percentage, but at the same time a 

 successively increasing addition to the body weight or milk yield, or both. 



