COMPOSITION OF MILK 21 



eighth milking. This colostrum milk, although it 

 is not in any way poisonous as human food, is 

 very undesirable for purposes other than food 

 for the calf, and should not be delivered to 

 a creamery or cheese factory until it is fit for 

 human use. 



Casein. The casein in milk varies with dif- 

 ferent animals from 1.8 per cent to 3.0 per cent, 

 but in the individual it is quite constant. This 

 casein, with the albumen, comprises what is 

 known as proteids of milk. These proteids are 

 very valuable as food and furnish the muscle 

 producing elements so essential. The casein and 

 the fat constitute what are known as the cheese 

 solids of milk. These two components determine 

 the value of the milk for cheese production. 



Milk sugar. The sugar in the milk is an impor- 

 tant constituent, but should not be confused with 

 commercial cane sugar. Milk sugar is only about 

 one-fourth to one-fifth as sweet as ordinary cane 

 sugar. It is manufactured from the whey at a 

 few cheese factories in this country, located 

 where large quantities of whey are available, 

 but has very little commercial value, being used 

 only in the preparation of modified milk. 



Kind treatment necessary. A great deal has 

 been written in regard to the quality of milk as 

 affected by varying conditions, such as slow and 

 fast milking, sudden changes in the feed, and the 



