MILK AND ITS CARE. 171 



in combination with the casein and albumen, 

 and make up about .7 per cent, of average milk. 



IV. Color. 



The normal white color of milk is mostly due 

 to the casein. The yellow shade observed in 

 varying degrees is due to a specific coloring 

 matter called lactochrome, which is combined 

 with the butter fat, and gives butter the natural 

 yellow color. The amount of this coloring mat- 

 ter varies greatly, being affected the most by 

 the feed of the cow, but also by breed and in- 

 dividuality of the cow. Green feeds, as grasses, 

 give the highest color, while dry feeds, as hay 

 and grain, the least color. The Guernsey and 

 Jersey breeds produce the highest colored milk 

 and butter; the Holstein and Ayrshire the 

 lightest colored. The yellow color of milk is 

 often taken as an index of its richness, but this 

 cannot be relied upon, and is of little value as a 

 means of judging the quality of milk. 



V. Variation in Quantity and Quality. 



i. Breed. Certain breeds of cows are charac- 

 terized by producing rich milk, and others by pro- 

 ducing unusually large quantities. The breeds 

 that produce rich milk produce a less quantity, 

 on the average, than do those producing the 

 poorer quality. In order of richness, the com- 

 mon breeds stand as follows : Jersey, Guernsey, 

 Short Horn, Red Poll, Ayrshire, Holstein. The 

 Holstein breed stands considerably ahead in 



