RELATION OF BACTERIA TO THE DAIRY. 1/7 



hardly prepared to learn that, by the time it has been drawn 

 from the cow, received in the milk pail and removed from the 

 cow stall to the dairy, it may be contaminated with bacteria to 

 the extent of several thousand per c.c. But this is frequently 

 and, indeed, commonly the case. The number of bacteria in 

 freshly drawn milk will vary greatly with the conditions exist- 

 ing in the dairy. There may be only a few score in each c.c. 

 or, under exceptional conditions a smaller number still, but it 

 is much more likely that the milk contains many thousands of 

 bacteria by the time it has been removed from the cow stall. 

 The actual number is of no special significance, except as an 

 indication of the cleanliness of the dairyman in handling his 

 cows and in caring for his dairy. 



All of the troublesome changes which occur in milk and 

 make this product so difficult to handle are due to the action 

 of bacteria upon the milk ; hence it is a universal desire 

 of the dairyman, the milk distributor and the consumer, to 

 have the bacteria as few as possible. Every one wishes the 

 milk to remain sweet, and this is possible only as the number 

 of bacteria is kept small. It becomes a matter of much im- 

 portance to learn the sources from which these milk bacteria 

 are derived. Knowledge upon this point will enable the 

 dairyman to adopt a few precautions in the production of and 

 caring for milk which will considerably reduce their number. 

 A small amount of attention given in the right direction will 

 produce much better results than a much larger amount, mis- 

 directed and indiscriminately applied. 



The Cow. The chief sources of milk bacteria are the cow and 

 the milk vessel. Although the cow secretes milk in a sterile 

 condition it is by no means sterile when it leaves the milk 

 duct. There are always some bacteria in the milk ducts ready 

 to be washed into the milk pail with the first jet of milk. At 

 the close of the milking enough milk is left in the duct to 

 furnish food for bacteria which may get in through the ex- 

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