OUEDLING 



229 



when the sale of milk is intended, than for the 

 economic production of butter or cheese. The 

 average results obtained at three American stations as 

 to the produce of milk and of milk fat, and as to 

 cost of food, with various breeds of cows, were as 

 follows : — 



The Holstein cow thus produced the cheapest milk, 

 and the Guernsey cow the cheapest butter. If 

 ordinary cheese is to be manufactured, the presence 

 of an exceptional amount of fat in the milk is not 

 desired, and is, in fact, uneconomical, as the fat 

 demands more food to produce it than any other 

 constituent of the milk. 



The influence of diet on the production of milk and 

 butter has been already considered (p. 203). 



Ctirdling.— Healthy milk as it occurs in the cow's 

 udder is free from the organisms which produce 

 change; but in the operation of milking, and during 

 subsequent exposure to air, bacteria, moulds, and 



