158 



CITY MILK SUPPLY 



covered with wire lath and two coats of cement down to within 3 ft. 

 of the floor; the area between the cement and the floor was covered with 

 zinc. In putting the barn in order after plastering, the stanchions, 

 floors and mangers were thoroughly cleaned. Then milk from the same 

 six cows was tested again on 6 days, every effort being made to keep the 

 barn management and bacteriological examination identical to that which 

 obtained in the unplastered barn except that in this series of tests no 

 dust was permitted to accumulate. Next, the woodwork and ironwork 

 of the stable were painted and a series of six tests with the same six 

 cows was run under these conditions. A summary of the counts ob- 

 tained are shown in Table 45. 



TABLE 45. AVERAGE GERM CONTENT OF MILK UNDER VARIOUS BARN CONDITIONS 

 (HARDING, WILSON, RUEHLE AND SMITH) 



The table needs little explanation further than to state that the figures 

 in the columns headed difference are obtained by deducting from the 

 bacteria in the whole milk the bacteria in the strippings, it having been 

 found by the authors that the bacteria in the strippings fairly represent 

 the number of bacteria in the udder. 



In commenting on the results from the 212 samples the authors point 

 out that they show that in the last two sets of tests when the barn was 

 clean, the difference in germ content of the milk was greater than the 

 difference between the results when the barn was clean and when it 

 was dirty. The gist of the matter is that the influence of these barn 

 conditions upon the germ content of the milk was so slight that it was 

 immeasurable. 



About a year after the station barn was plastered a series of tests was 

 made to determine the effect of the whitewashing of a barn on the bac- 

 terial count of milk produced in it ; the experiments were suggested by an 

 ordinance that is found in many health codes requiring dairy barns to be 

 whitewashed once a year or oftener. For 20 successive days the milk 

 of each of three cows was sampled and plated. Comparison of the 

 results shows that the general average of the 60 samples taken after white- 



