THE RELATION OF MICROORGANISMS TO MILK 

 Bacteria in Different QuARTteRS op Cow's Udder* 



371 



Average germ content per c.c. in 316 samples from herd of 1900-02 518 



Average germ content per c.c. in 730 samples from herd of 1910-11 4so 



Average germ content per c.c. in 184 samples from herd of A. G. L 320 



Average germ content per c.c. in 1,230 samples from 78 cows 428 



The number of organisms normally found in the udder is much 

 smaller than would be expected when we consider the fact that ideal' 

 conditions of food and temperature are provided there for bacterial 

 growth. The relatively small number of organisms is perhaps due to 

 some germicidal action existing in the udder. Attempts to increase the 

 germ content in the udder by injecting cultures of different species of 

 saprophytic bacteria have failed to produce a continued increase, the 

 injected organisms usually decreasing very rapidly in numbers until 

 they disappear at the end of a few days. From the standpoint of 

 ordinary market milk, the number of bacteria found in the healthy 

 udder is so small that it is of little commercial importance. In dairies 

 where a very small germ content is desired, however, this source, of in- 

 fection must be taken into account and in certain cases individual cows, 

 which normally have a high bacteria content in the udder, can be dis- 

 carded to advantage. 



It is evident that many species do not find the conditions in the 

 udder suitable for their growth, since investigations have ^hown that 

 comparatively few species exist for any length of time in the healthy 

 udder. Certain t3T)es of micrococci are the predominating forms with 

 occasional cultures of other species. The Bad. lactis acidi type does 



• Harding and Wilson: Technical Bui. No. 27, N. Y. Agril. Exp. Sta., 1913. 



