PRODUCTION OF MILK OF LOW BACTERIAL CONTENT. 



25 



Fig. 15. — Condition of the flank and udder of one of the 

 cows during Experiment No. 7. 



During this ex- 

 periment the aver- 

 age count of the 

 middle milk taken 

 directly from the 

 udder of two cows 

 was 1,172 bacteria 

 per cubic centimeter, 

 which, subtracted 

 from 2,667, the 

 count of the entire 

 milking which was 

 milked into small- 

 top pails, leaves 

 1,195, or the number 

 of bacteria per cubic 

 centimeter intro- 

 duced into the small- 

 top pari by external 

 contamination. 



Similarly the aver- 

 age udder count of 

 middle milk of the two cows milked into open pails was 1,557, which, 

 when subtracted from the average of the open pail, 4,947, gives a 

 difference of 3,390 bacteria per cubic centimeter to represent the 

 number introduced by external contamination. 



In this final experiment we again used a few simple factors, 

 namely, sterilized utensils, clean cows with clean udders and teats, 

 and the small-top pail. The figures confirm the previous results. 



CONTAMINATION OF MILK BY UNSTERILIZED UTENSILS. 



In this work the results have indicated that generally the greatest 

 contamination of milk comes from the use of unsterilized utensils. 

 Since that factor is so important in the production of low-count 

 milk it deserves special consideration, and therefore additional data 

 on the subject are presented. 



Table 9 shows the results of the bacterial examination of 60 sam- 

 ples of milk from both sterilized and unsterilized small-top pails. 

 Each number represents two samples taken at the same milking, 

 when two cows were milked into a sterilized pail and two into an un- 

 sterilized one. All the cows were cleaned and bedded, but the udders 

 were not washed. The 60 samples from the sterilized pail showed an 

 average bacterial count of 6,306, compared with 73,308 for the un- 

 sterilized pail, a difference of 67,002, which represents the average 

 number of bacteria per cubic centimeter introduced through unsteril- 

 1 —18— Bull. 642 4 



