THE RELATION OF MICROORGANISMS TO MILK 443 



Results of extended trials in different barns demonstrate the fact 

 that approximately two- thirds of the organisms which would fall into an 

 ordinary open pail are kept out by the use of a pail of the type shown in 

 No. 3, figure 142. The following figures give average results of trials 

 in three different barns. 



BACTERIAL COUNTS OBTAINED WITH OPEN AND SMALL TOP PAILS 



Barn Kind of pail Average bacterial count 



f Open 1,610 



\ Covered 280 



/ P Cn 6 000 



\ Covered 3,ooo 



/ Open 33,ooo 



' \ Covered I >74 



AVOID DUST IN THE ATMOSPHERE. Many of the necessary 

 operations of the cow stable stir up large quantities of dust and fill the 

 air with microorganisms. It is astonishing to see how many bacteria 

 can adhere to a small piece of hay or may be found in a gram of some 

 of our common dairy feeds. When these materials are fed dry just 

 previous to milking time, the atmosphere of the stable will be filled 

 with organisms some of which may settle into the milk while it is ex^ 

 posed during the process of milking. The effect of this source of con- 

 tamination in one stable may be seen by the following experiments: 



BACTERIAL CONTENT OF MILK AS AFFECTED BY FEEDING DRY HAY AND GRAIN 



Experiment Date Nature of sample Number bacteria per 



In another stable* where the sanitary conditions were above the aver- 

 age and where all the conditions were carefully controlled, the atmos- 

 phere added from 7 to 937 germs to each c.c. of the milk, the number 

 varying with the amount of dust in the air. 



* X. Y. (Geneva) Agr. Exp.[Sta.'^Bull/40O. 



