42 SOURCE OF BACTERIA IN MILK. 



udder for some distance. But such a method of milking 

 has proved impractical. 



The Cow. From the moment the milk leaves the milk 

 ducts it is subject to a number of external sources of bac- 

 terial contamination. The most important of these is prob- 

 ably the cow herself. At the present time much greater 

 attention is given on the part of the dairyman to cleanliness 

 of his cows than a few years ago, and hence the contamina- 

 tion of milk from this source is probably less to-day than 

 it was ten years ago. But in the best dairies the skin of the 

 cow is likely to be more or less covered with dirt unless the 

 cow is carefully groomed daily, and even daily grooming 

 does not keep her clean. In the less carefully kept dairies, 

 and particularly in poorly kept dairies, which two classes 

 represent the majority, the condition of the cow in mat- 

 ters of cleanliness is surprisingly bad. In many barns 

 the animal is rarely groomed and becomes covered with 

 excrement and all sorts of miscellaneous filth, especially 

 on her flanks. This filth dries upon her skin and, being 

 completely loaded with bacteria, the result is that such 

 dried filth on the flanks of the cow becomes a constant 

 source of bacteria in the milk. Every motion that the cow 

 makes, and every time she switches her tail, showers of filth, 

 loaded with bacteria, drop from her body, filling the air in 

 her immediate vicinity. Indeed, even when she is perfectly 

 quiet there is a considerable quantity of bacteria-laden filth 

 and dust which falls from her flanks. During the milking, 

 when her body is more or less rubbed by the milker and 

 when she is herself undergoing various motions, there is a 

 constant shower of bacteria from the animal into the milk 

 pail. This is not a matter of simple theory, but one which 

 has been demonstrated by bacteriological tests. The dust 

 and dirt that falls into the milk pail during the milking has 

 frequently been collected, analyzed, and found to contain 

 bacteria in very large numbers (38). 



