54 SOURCE OF BACTERIA IN MILK. 



ing. The throwing of the dry hay from the mow is 'sure 

 to fill the air with dust, and if the cows are eating the hay 

 during the milking they are scattering in the air millions of 

 bacteria. The dairyman should remember that the use of 

 dry hay in the milking room is, under all conditions, a source 

 of troublesome bacterial contamination, for the bacteria are 

 so light that they will float in the air many hours after they 

 have been disturbed by the throwing of the hay from the mow 

 and, even if the feeding occurs after milking, the air does not 

 become wholly free from bacteria before the next milking. 



The so-called " wet milking " should never be allowed. 

 Wet milking only results in washing the hands of the farmer 

 in the milk, for the moisture with which the hands are wet 

 will cause the bacteria which chance to be on the hands of 

 the milker, or the outside of the teats, to run down and 

 mingle with the milk. 



Treatment of Milk after Milking. The longer milk is ex- 

 posed to the air, other things being equal, the greater the 

 amount of contamination. This, of course, represents a 

 general truth of which there can be no doubt. But it must 

 be remembered that it is the dusty, dirty air of the barn and 

 milking stall that furnishes the greater quantity of bacterial 

 contamination, while the pure out-of-door air does not con- 

 tain enough bacteria to produce much trouble. If the milk 

 can be immediately removed from the barn and carried to a 

 clean rriilk room the subsequent contamination from expos- 

 ure to the air is not very great. But even though this be 

 true, it is always wise to cover the milk as quickly as pos- 

 sible after it has been drawn. The use of sterilized bottles 

 for milk distribution has produced an improvement in the 

 quality of the milk so far as concerns external impurities. It 

 is quite a general practice to run the milk over a milk aerator, 

 and then to bottle at once. The milk cooler and aerator, of 

 which there are several kinds in use, always exposes a con- 

 siderable surface of milk to the air for a few moments, and 



