THE RELATION OF MICROORGANISMS TO MILK 441 



These figures indicate that the utensils may play a much more impor- 

 tant part in determining the total germ content of milk than was 

 formerly supposed. The use of steam is the most efficient means of 

 sterilizing all dairy utensils, but boiling water may give very satisfac- 

 tory results if used at actual boiling temperature. If not used at the 

 boiling temperature some of the resistant organisms will not be 

 killed and will be left to inoculate the fresh milk. The ropy milk 

 organism, B. lactis viscosus, often remains in the utensils from day to 

 day in this way. 



WATER SUPPLY. Sometimes the water used for washing the dairy 

 utensils is a serious source of contamination. Serious epidemics of 

 disease have been traced to this source where the utensils were washed 

 with water contaminated by typhoid or other disease organisms 

 and were not sufficiently sterilized to kill those remaining in the uten- 

 sils. Such dairy troubles as ropy milk and gassy milk may be caused 

 by the water used for washing purposes. 



METHODS OF PREVENTING CONTAMINATION OF MILK 



INDIVIDUAL Cows. Normally the number of microorganisms 

 found in the udder is not sufficient to be a serious source of contami- 

 nation for market milk. There are, however, certain cows which 

 have a much higher germ content than others, and where a very low 

 count is desired in the milk, it may sometimes be advisable to elimi- 

 nate such cows from the herd. 



CARE OF THE Cow's BODY. In order to reduce to the minimum the 

 contamination from the cow's body, she should be kept as clean as 

 possible. Dust should not be allowed to accumulate in her coat. 

 It is well to keep the hair of the flank and udder clipped in order to 

 prevent the accumulation of dust and also to facilitate the process of 

 cleaning. The use of a damp cloth for wiping the flank and udder 

 at milking time is a very efficient means of reducing this source of 

 contamination.. The beneficial effect of this method may be seen 

 in the following table. 



Even when considerable care is taken to clean the surface of the 

 cow's body, there will still be some organisms which may fall into the 

 pail at milking time. This number can be very materially lessened 



