FARM ANIMALS 191 



with another person affected with a contagious 

 disease, should milk cows during such time as 

 he is likely to carry infection. The cows should be 

 thoroughly groomed before milking and the milk- 

 ers' clothes and hands should also be free from 

 filth. 



In order to prevent fermentation and other bad 

 effects which must necessarily arise from the filth 

 and bacteria which get into milk even under the 

 best conditions it is desirable to adopt certain other 

 practices in order to make as little room as may be 

 necessary for the development of such bad results. 

 On this account milk should be strained and aerated 

 immediately after milking. It must at once be 

 removed from the milking stable and cooled down 

 to a temperature of forty to sixty degrees F. On 

 the farm it is often impracticable to cool milk to 

 forty degrees F., but it keeps better if this temper- 

 ature can easily be obtained. If the milk is to be 

 run through a separator this process should take 

 place while it is warm and fresh or, if that be im- 

 possible, and the milk is allowed to cool, it is best 

 to warm it up again to a temperature of one hundred 

 degrees F. or above, before running through the 

 separator. If there is any question about the qual- 

 ity of the milk as regards bacteria, and particularly 

 if any doubt exists regarding the fermentation of the 

 milk from disease germs it should be pasteurized 

 at a temperature which will destroy these organ- 

 isms. This may be accomplished by heating the 

 milk to a temperature of one hundred and forty 

 degrees F. for about twenty minutes. Not all 

 bacteria will be destroyed by this method, but the 

 milk will be rendered practically safe for all pur- 

 poses. If milk is cooked at the ordinary boilii 

 temperature, the composition is slightly cl 



