334 SCIENTIFIC FEEDING OF ANIMALS 



food, it is not possible to produce a butter which 

 will in all respects resemble the food fat. The 

 mammary gland is apparently unable to work up 

 those fats which are foreign to the body. 



The carbohydrates also are not without influence 

 upon the composition of the butter. It has been 

 observed that towards autumn the butter from 

 cows on pasture has behaved like a mixture of 

 margarine and butter when chemically examined, 

 and that feeding with mangel tops has the power 

 to remove this drawback. Following upon this 

 observation, it was discovered that the improve- 

 ment must be ascribed to the sugar in the mangel 

 tops, and that sugar-containing foods, as well as 

 sugar itself, have the power of increasing the amount 

 of compounds of volatile fatty acids (glycerides) in 

 the butter. 



(/) The so-called specific effects of the food-stuffs. 



Alongside the effect which ordinary foods of good 

 quality exercise through the nutrients which they 

 contain there are, according to very prevalent 

 views, other powers which affect the produc- 

 tion of flesh or milk for good or ill. It certainly 

 cannot be denied that when a feeding-stuff agrees 

 with an animal it can increase the nutritive value, and 

 also that the palatableness not only influences the 

 consumption, but also the food value, particularly 



