340 FARM ANIMALS 



roundings, temperature, light, and ventilation. A last 

 element in securing rich yields, both in quantity and 

 quality, is the milker himself. If quiet, even-tempered, 

 and gentle, he will get more milk than if the reverse 

 are his characteristics. If he is a rapid milker, he will 

 get more and richer milk as a result, for the expert 

 milker gets the most butter fat from the cow. 



PURE MILK 



The only way milk can be kept pure is through 

 cleanliness. The barn must be clean, the cow must be 

 clean, the milker must be clean, the utensils must be 

 clean. Bacteria abound everywhere, in the dust of 

 the barn, on the animal milked, on the person of the 

 milker, and unless great care is taken, they enter the 

 milk in large numbers. These are not necessarily 

 disease-producing bacteria, although such may also 

 be present, but they are organisms harmful to the sweet- 

 ness and purity of milk. They multiply rapidly in 

 warm fresh milk, and unless preventive measures are 

 taken, soon cause the milk to sour. Cooling the milk 

 while it is perfectly fresh will not kill the germs, but 

 it will retard their growth and increase, and this pre- 

 vents its turning sour so soon. Pasteurizing the milk, 

 that is, heating it to i3O-i6o F., keeping it there 

 25 minutes, and then rapidly cooling it to 50, will 

 kill most of the germs and keep the milk sweet for some 

 time, especially if it is carefully sealed in air-tight vessels. 



Composition of Milk. - - The average composition 

 of the milk of the cow in this country is as follows : 

 water, .875; milk sugar, .0475; fat, .036; casein, .029; 

 mineral matter, .0075 ; albumin, .005. 



The fat in milk is the constituent that makes butter. 



