SIGNIFICANCE OF COLON COUNT IN MILK. 



17 



relation between the quantity of manure and the colon count. This 

 is undoubtedly due to the variable number of such organisms found 

 in cow feces, and to the different degrees of such contamination 

 introduced through unsterilized utensils. 



The results thus far presented show very clearly that unsterilized 

 utensils play a prominent part in the contamination of milk with 

 organisms of the colon-aerogenes group. To emphasize this point 

 an experiment was conducted in which the milk from three cows went 

 into sterile utensils while that from three others went into unsterilized 

 utensils which had been allowed to stand for 24 hours before washing. 

 All six cows were clean and were kept in a clean barn, and the only 

 chance for difference in the contamination of the milk was due to the 

 unsterilized utensils. The results in Table 9 show that in the milk 

 handled in sterilized utensils there were no organisms of the colon- 

 aerogenes group present in 1/100 of a cubic centimeter, while all the 

 samples of milk handled in unsterilized utensils showed the pres- 

 ence of these organisms, ranging from 1,100 to 350,000, and averag- 

 ing 80,650 per cubic centimeter in the fresh milk. This, of course, 

 represents contamination from unsterilized utensils which were 

 handled in an unusual manner, but it serves to emphasize the impor- 

 tance of sterilized utensils in connection with the colon count. 



Table 9. — Effect of sterilized utensils on colon count. 



Sample No. 



Sterilized utensils. 



Utensils not sterilized 

 and not washed for 24 

 hours. 



Total 

 count. 



Colon 

 count. 1 



Total count. 



Colon 

 count. 



1 



2 

 3 



4 

 5 

 6 



7 

 8 



Average... 



17,100 

 4,600 

 7,300 

 5,700 

 3,900 

 4,300 



10, 200 

 6,300 





 

 

 

 

 

 

 



2,050,000 



2, 800, 000 



2,320,000 



2, 210, 000 



254, 000 



680, 000 



450, 000 



365, 000 



91, 000 



72, 000 



120, 000 



350, 000 



1,100 



1,400 



5,200 



4,500 



7,425 





1,391,125 



80, 650 





1 indicates none in 1/100 of a cubic centimeter. 



At this point it is possible to answer the question "How many 

 organisms of the colon-aerogenes group can be introduced during 

 milking?" The answer is, not over 2,000 per cubic centimeter, and 

 is based on the examination of 254 samples produced under both 

 clean and unusually filthy conditions, only one sample of which 

 showed a colon count of over 2,000 per cubic centimeter in fresh 

 milk. A summary of these counts is shown in Table 7 and also 

 in figure 1. If this is the maximum number of organisms of the 

 75649°— 18— Bull. 739 3 



