A STUDY OF THE UDDER FLORA OF COWS.* 



H. A. HARDING and J. K. WILSON. 



SUMMARY. 



(i) An examination of 1230 samples of milk direct from the 

 udders of 78 cows indicates that the germ content is smaller than 

 has previously been assumed, the average of these samples being 

 428 per cc. 



(2) The bacteria were not evenly distributed among the quarters 

 of the udder, there being about three times as many per cc. in the 

 back as in the front quarters. The factor controlling this dis- 

 tribution has not been found. 



(3) Neither the age of the cow nor the period of lactation ex- 

 erted any marked influence upon the germ content of the udder. 



(4) When classified in accordance with the system of the 

 Society of American Bacteriologists the organisms found in about 

 900 samples fell into 71 groups. The udder flora is characterized 

 by a lack of motility, of spore formation and of gas formation. 

 It is largely composed of micrococci and is practically all Gram 

 positive. 



INTRODUCTION. 



Bacteria exist in varying numbers in the udders of all cows. 



Therefore even extreme cleanliness in the dairy will not reduce 



the germ content of the milk below the number which it contains 



while it is yet within the udder. The finding by Hastings and 



Hoffmann 1 of an apparently healthy cow with an average udder 



content of 191,000 germs per cc, while an extreme case, shows 



the possible magnitude of this phase of the milk question. With 



1 Hastings, E. G.. and Hoffmann. C. Bacterial content of the milk of indi- 

 vidual animals. Wis. Agr. Exp. Sta. Research Bui. 6. 1909. Also in Ann. 

 Rpts. of same Station 25 & 26 (19-08-1909) : 189-196. 1910. 



Reprint of Technical Bulletin No. 27, March. 1913. 



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