36 



it is a fact that bacteria cannot increase rapidly in a temperature 

 of less than 55° ; when the temperature gets clown to this their in- 

 ci^ease is pi'actically suspended. Hence, if the number of bacteria 

 is reduced to a minimum to begin with, and then if the milk is 

 promptly cooled with ice or spring water to 55° or below, the 

 keeping qualities of the milk will be greatly increased, aud there 

 will be no trouble from sour milk in the ordinary course of getting 

 it to consumers. One authority says that by these precautions 

 milk may be kept merchantable a week or ten days. This is of 

 the utmost importance to farmers, particularly those who ship 

 milk to cities. 



The whole " secret " of avoiding sour milk trouble is in three 

 words, — cleanliness, prompt cooling. With these milk will with- 

 stand even the traditional influences of the thunder shower. 



The first source of the infection of milk with the bacteria of 

 souring seems an exception to the above general statement. 

 These bacteria get into the milk pail in the first few drops drawn 

 from the udder. At the close of the previous milking a little milk 

 is always left at the end of the teat, a drop often remaining in the 

 little orifice near the end of the teat. Here the bacteria multiply 

 to an enormous extent, the warmth of the animal body furnishing 

 excellent conditions for their increase. When the next milking 

 is commenced they are washed into the pail to contaminate the 

 whole of the milking and shorten its life. A material increase 

 of the keeping properties of milk will follow from milking on the 

 floor the first streams from each teat, enough to rinse them out. 



The next and most common source of infection is through the 

 air which is always loaded with bacteria. The number of bacteria 

 in the air varies very largely but the germs are more numerous in 

 inclosed spaces like rooms than in the open air. Hence, when 

 cows are milked in the barn the milk will have more bacteria than 

 when they are milked in the open field. We cannot tell all of the 

 ways in which these bacteria get into the air, but we do know that 

 they come from particles of manure, skin, food, hair, threads aud 

 cobwebs. They are intimately associated with the dust floating in 

 the air. From the body of the animal, the hands of the milker or 

 his clothes may also come the troublesome little " bugs." Hence 

 the more filthy the conditions the more bacteria and the sooner 

 the milk sours. Professor Sedgwick says " short-lived milk is 

 usually filthy milk." Another authority says : " Sour milk is due 

 to dirty handling." Grotenfelt says :" The impure air in the 

 stable is one of the main causes of bacterial infection of milk." 



Stables. — The barn should be cleaned at least annually, remov- 

 ing dust and cobwebs from timbers and corners, and cleaning out 



