PRODUCTION OF MILK OF LOW BACTERIAL CONTENT, 59 



sterilizer described in Farmers' Bulletin 748 x was used very success- 

 fully for the sterilization of utensils on the farms. 



6. Small-top pails were found to lessen the quantity of manure 

 which may gain entrance into milk and to assist in lowering the 

 bacterial count. 



7. The sediment test was found to bear a somewhat close relation to 

 the number of bacteria in fresh, unstrained milk handled in sterilized 

 utensils. 



8. From an examination of a large number of samples of fresh milk 

 produced under varying conditions in an experimental barn and of 

 samples from a number of farms, it is believed that as a general rule 

 the bacterial content is relatively low. It would seem that when the 

 count is in the millions it is the result of bacterial growth in the milk 

 while being held. 



9. To show the growth of bacteria in milk held at various tempera- 

 tures for varying periods, a large number of samples were held at 

 4.4°, 10°, 15.5°, and 21.1° C. (40°, 50°, 60°, and 70° F.). It is abso- 

 lutely necessary, if milk is held on the farm, to keep it near 10° C. 

 (50° F.) or lower, in order to restrain bacterial growth, if the dairy- 

 man wishes to market milk of low bacterial content. 



CONCLUSIONS. 



The results of the experiments indicate that it is possible for the 

 average dairyman on the average farm, without expensive "barns and 

 equipment, to produce milk (practically free from visible dirt) 

 which when fresh has a low bacterial count. By the use of the three 

 simple factors, namely, sterilized utensils, clean cows with clean ud- 

 ders and teats, and the small-top pail, it should be possible on the 

 average farm to produce milk which corresponds closely to milk as 

 it leaves the udder of the cow. A fourth factor of holding milk at 

 as near 10° C. (50° F.) as possible is also absolutely necessary. 



To emphasize the value of the three simple factors, figure 23 shows 

 the average bacterial counts of milk produced under the various con- 

 ditions described in this bulletin. The results will not be discussed 

 in detail, but in a general way the figure gives a picture of the 

 results of the experiments in the order in which they were conducted. 

 The experiments were begun with dirty conditions and unsterilized 

 utensils, and milk of high bacterial count was obtained. Next the 

 factor of sterilized utensils was introduced, followed by the addi- 

 tional factor of clean udder and teats. A combination of the factors 

 and the use of a small-top pail permitted the production of a low- 

 count milk, which closely corresponded to that drawn directly from 

 the udder. In order to check the value of the essential factors, they 

 were again eliminated until a high-count milk was produced, then 

 reintroduced until a low-count milk was again obtained. 



1 Farmers' Bulletin 748 will be sent free to any one on application to the department. 



