12 MARKET DAIRYVING 
in some cows to produce a soft butter fat, in others to 
produce a hard butter fat, even in cows of the same breed. 
Soluble Fats. The soluble or volatile fats, of which 
butyrin is the most important, give milk and sweet cream 
butter their characteristic flavors. Butyrin is found only 
in butter fat and distinguishes this from all vegetable 
and other animal fats. 
The percentage of soluble fats decreases with the period 
of lactation, also with the feeding of dry feeds and those 
rich in protein. Succulent feeds and those rich in carbo- 
hydrates, according to experiments made in Holland and 
elsewhere, increase the percentage of soluble fats. This 
may partly account for the superiority of the flavor of 
June butter. 
It may be proper, also, to discuss under volatile or 
soluble fats those abnormal flavors that are imparted to 
milk, cream, and butter by weeds like garlic and wild 
onions, and by various feeds such as beet tops, rape, par- 
tially spoiled silage, etc. These flavors are undoubtedly 
due to abnormal volatile fats. 
Cows should never be fed strong flavored feeds shortly 
before milking. When this is done the odors are sure 
to be transmitted to the milk and the products therefrom. 
When, however, feeds of this kind are fed shortly after 
milking no bad effects will be noticed at the next milking. 
Albumenoids. These are nitrogenous compounds 
which give milk its high dietetic value. Casein, albumen, 
globulin and nuclein form the albumenoids of milk, the 
casein and albumen being by far the most important. 
Casein. ‘This is a white colloidal substance, possessing 
neither taste nor smell. It is the most important tissue- 
forming constituent of milk and forms the basis of an 
almost endless variety of cheese. 
