1917] 



DAIRY FARMINC 



-DAIRYING. 



685 



germ <.'ontent was 17 and the highest was 218,250 bacteria per cubic centimeter 

 of milk; in barn 2 the lowest was 3 and the highest was 33,000; and in barn 3 

 the lowest was 307 and the highest was 63,835. "These are wide limits of 

 variation in the germ content of milk produced under uniform barn conditions." 

 The following table shows the grouping of all milk samples according to 

 germ content and the average germ content of the milk from the three barns: 



Arf-angement of milk samples according to germ content and average number 

 of bacteria per cubic centimeter. 



Most of the samples of high germ content in barn 1 came from a few ani- 

 mals. One of these animals persistently gave milk with high germ content 

 and subsequent studies showed that her udder was the source of these large 

 numbers of bacteria in her milk. Data are tabulated showing the average 

 content of the milk of each animal for each of the two j-ears. Of the 72 

 averages in barn 1, 30 were below 1,000 bacteria per cubic centimeter of milk, 

 36 were between 1,000 and 5,000, only 7 were over 5,000, and of these 7 only 2 

 were over 10,000. In bam 2, 30 of the 47 averages were below 1,000, and the 

 highest average was only 3,599. In barn 3 aU the averages were above 1,000 

 bacteria per cubic centimeter of milk, 11 were below 5,000, 6 were between 5,000 

 and 10,000 and 2 were over 10,000. 



It is thus seen that in the production of milk of low germ content the udder 

 of some cows may become the principal source of contamination. It is stated 

 that " no conclusion can be drawn from the data concerning the relative im- 

 portance of the practice of wiping the udders, as compared with the other sources 

 of contamination in these barns. The data, however, do point to the conclusion 

 that the wiping of the udders under the conditions obtaining in these barns 

 did not affect the germ content of the milk to any appreciable extent." 



Commenting on the results of this investigation, the authors state that it 

 might be argued from the results obtained in barns 1 and 2 " that a dirty barn 

 does not contribute more bacteria to the milk than a clean barn. Such con- 

 clusion, however, would be against a well-established fact. This apparent 

 discrepancy is only a side issue to the general problem, and it would be a mere 

 conjecture to attempt to explain it. The real significance of the results from 

 these two barns lies in the fact that the number of bacteria in the milk from 

 both barns was remarkably small, and that the difference in the conditions 

 and the operations tn the two barns exerted practically negligible influence 

 upon the germ content of the milk. 



" Even more significant are the results from barn 3. The average contami- 

 nation here was 5,777 bacteria per cubic centimeter. This milk, so far as the 

 germ content was concerned, would meet the requirements for certified milk, 

 and yet the conditions of the barn as to cleanliness were such thac it is doubt- 

 ful whether the milk produced here would have been admitted to the milk 

 supply of some cities. These results must not be construed as a defense of 



