PRODUCTION OF MILK OF LOW BACTERIAL CONTENT. 



37 



Table 1G. — Number of bacteria in fresh cow manure. 



Sample No. 



Bacteria 

 per gram. 



14, 500, 000 



51,000,000 



3, 500, 000 



12, 009, 000 



40, 000, 000 



8, 000, 000 



52, 000, 000 



23,300,000 



650, 000, 000 



53, 000, 000 



15,000.000 



12 1 160,000,000 



13 30,000,000 



14 19,700,000 



15..- 690,000,000 



Sample No. 



17 



18 

 19 



20 

 21 



22 

 23 

 21 

 2.") 

 26 

 27 

 28 

 2!) 

 30 



Bacteria 

 per gram. 



Sample No. 



31 



32 

 33 

 34 



3.". 

 36 

 37 



38 

 39 



40 

 41 

 42 

 43 

 44 

 45 



Bacteria 

 per gram. 



6,200,000 



5, 800, 000 



7, 800, 000 



6, 900, 000 



41,000,000 



88, 000, 000 



14,500,000 



11,000,000 



55, 000, COO 



5, 000, 000 



32, 000, 000 



13, 000, 000 



40, 000, 000 



9, 500, 000 



26, 300, 000 



Sample No. 



46 



47 



48 



49 



50 



51 



52 



53 



54 



55 



56 



57 



Average 



Bacteria 

 per gram. 



6,800,000 



9, 400, 000 



71,000,000 



38, 700, 000 



17, 200, 000 



41, 000, 000 



60, 000, 000 



10, 400, 000 



8, 700, 000 



3, 200, 000 



2, 900, 000 



11,500,000 



49, 645, 614 



Table 11, 



-Theoretical number of bacteria which may be added to milk by vary- 

 ing quantities of manure. 



Quantity of wet 

 manure added to 

 1 pint of milk. 



Number of bac- 

 teria added to 



each cubic centi- 

 meter of milk. 



Oram. 

 0.5 

 .4 

 .3 

 .2 

 .1 



.075 

 ,05 

 .025 

 .01 



52, 854 



42, 283 



31,712 



21,141 



10, 571 



7,907 



5,285 



2,642 



1,057 



In order to show how much manure would be added to the milk, 

 on the basis shown in Table 17, Plate VI shows a number of sedi- 

 ment disks. 1 It will be seen from the figure that 0.5 of a gram of 

 wet manure represents a quantity far in excess of that found in milk 

 as produced on an average farm, and by referring again to Table 17 

 it is evident that this excessive quantity of manure would add only 

 52,854 bacteria per cubic • centimeter. If 0.1 of a gram of manure 

 were added to a pint of milk, that quantity would add only 10,571 

 bacteria to each cubic centimeter. 



It is realized, of course, that these figures are only relative because 

 of the variation in the bacterial content of manure, and, furthermore, 

 that which does enter the milk is not necessarily fresh. The figures, 

 however, confirm former conclusions that manure, though an im- 

 portant source of contamination in general, is not so great a factor 

 as unsterilized utensils in causing high bacterial counts. 



1 The authors are indebted to George B. Taylor, of the Dairy Division, for this series 

 of disks showing definite quantities of fresh manure. 



