548 ANNUAL. REPORT OF THE Off. Doc. 



a well kept milk room petri plates sometimes showed no contamina- 

 tion and at other times very little. Those exposed in the milk room 

 averaged about 1-30 as many colonies as those exposed in another 

 room in the same building used for ordinary purposes. 



The use of the small top milk pail is the simplest way of reducing 

 contamination of milk due to particles falling into the milk while 

 it is being held under the cow's udder. It has been shov.n that 63 

 per cent, of the dirt is excluded by a partially covered milk pail. 

 These figures are the more striking when they are compared with the 

 percentage of dirt removed from milk by straining, namely only 47 

 per cent. 



The care of dairy utensils is a more important matter than many 

 people think. They should be washed and sterilized everytime after 

 they are used, and then they should be kept in a place as free as pos- 

 sible from dust. The ordinary cleaning preparations, such as Gold 

 Dust and Pearline, have considerable value as disinfectant agents 

 when used in the strength of 1,300 of water, as shown by Doane, of 

 the Maryland Experiment Station. His investigations proved that 

 these preparations in the strength named can be depended upon to 

 kill more than 90 per cent, of the organisms on the surface of dairy 

 utensils. But steam or hot water is the best agent for sterilizing 

 after cleansing. Eussell has shown the importance of sterilizing 

 utensils. Even exposure of one or two minutes to live steam re- 

 sults in killing almost all organisms. The necessity of protecting 

 utensils after once cleaned and sterilized is often overlooked. Bergey 

 reports that the first milk passing through a strainer contains 60,900 

 bacteria per c. c, while the milk passing after 200 quarts contained 

 only 3,350. Similar contamination results on the cooler and in a 

 tank below the cooler, and the first milk falling from the milk bot- 

 tle was found to contain 84,000 bacteria per c. c, while a sample 

 after 200 quarts had passed through the machine contained only 

 4,750 bacteria per c. c. 



About the same should be said regarding the cleanliness of the 

 attendants in the dairy as the cleanliness of the cow. It is highly 

 important to have the attendants in good health and for them to 

 wear some special garment while milking. 



Contamination of milk due to its age or storage conditions de- 

 pends upon the length of time it is kept and the temperature. The 

 importance of cooling to 50 degrees F. or lower is shown by the fol- 

 lowing figures: A sample was divide'd into four parts and these were 

 h£ld at different temperatures for 24 hours at the end of which time 

 the number of bacteria were as stated. 



45 degrees F., ' 445 colonies. 



50 degrees F., 3,162 colonies. 



55 degrees F., 67,170 colonies. 



68 degrees F., 134,340 colonies. 



In spite of all that can be done, milk becomes more or less con- 

 taminated and the dairyman is confronted with the question as to 

 how best to handle such milk. Filtration, certrifugalization, pre- 

 servatives, high pressure, vacuum, electricity, have all been experi- 

 mented with and without success. Pasteurization is recommended 

 by many persons and undoubtedly it is a good remedy under certain 



