UNITED STATES DEPARTMENT OF AGRICULTURE 



1 BULLETIN No. 739 £ 



Contribution from the Bureau of Animal Industry ?Jj 



JZ&'^P&U JOHN R. MOHLER. Chief J&P^&U 



Washington, D. C. 



PROFESSIONAL PAPER 



December 30, 1918 



THE SIGNIFICANCE OF THE COLON COUNT IN RAW MILK. 



By S. Henry Ayers and Paul W. Clemmer, Bacteriologists, Dairy Division. 



CONTENTS. 



Present status of the question 1 



Do organisms of the colon-aero genes group in- 

 dicate the presence of manure in fresh milk? 3 



Can milk be produced commercially without 

 contamination by organisms of the eolon- 

 aerogenes group? 9 



How many organisms of the colon-aerogenes 

 group can be introduced into milk during 

 milking? 12 



Why are high colon counts often found in raw 

 milk? 19 



Page. 

 Are both the B. coli and B. aerogenes types 

 present in milk; and if so, is their relative 



proportion of any value? 27 



Has the colon count any significance in raw 



milk? 31 



Significance in fresh milk 31 



Significance in milk that has been held ... 31 



Summary 32 



Literature cited 33 



PRESENT STATUS OF THE QUESTION. 



For many years the organisms of the colon-aerogenes group have 

 occupied a position of very great importance in the eyes of sanitarians. 

 From the public-health standpoint the quality of water supplies has 

 been determined by means of the number of these organisms present; 

 not because they are considered pathogenic but rather because they 

 are present in fecal material in large numbers, and therefore their 

 presence" in any considerable number in water may indicate the 

 presence of pathogenic organisms of fecal origin. 



Investigations have shown, however, that the colon bacillus is by 

 no means confined to the human intestines, but is often the pre- 

 vailing form in the intestines of many animals, including cows. It 

 would seem at first thought, therefore, that the presence of colon 

 organisms in milk might afford a valuable means for determining 

 pollution by cow feces. In fact, the determination of colon bacilli 

 in milk as a means of indicating manurial pollution has become quite 

 general on account of the value of the colon test as an index of the 

 purity of water and the apparent analogy between the contamination 

 of water by fecal material and the contamination of milk by cow 

 feces. 



75649°— 18— Bull. 739 1 



