CHAPTER IV 

 SANITARY MILK PRODUCTION 



Milk Must Satisfy the Purchaser. To bring good price, milk must 

 have good food value and certain other qualities that are affected by the 

 sanitary conditions under which it is produced. Care must be taken to 

 keep milk clean. 



Dirty Milk. The dirt that gets into milk is of many sorts and comes 

 from different sources. The large particles are noticed and objected to 

 by consumers but the invisible dirt that comes from a foul strainer cloth 

 or from the film of milk that dries on the carelessly washed pail escapes 

 attention, yet it is quite as likely to deterioriate the milk. Dirt from 

 various sources is not equally objectionable. That blown from a newly 

 ploughed field is regarded with less aversion than that blown from a 

 much-used driveway because the one is relatively free from animal ex- 

 cretions whereas the other is likely to contain them. The dirt or dust 

 raised in a barn by tumbling hay from the mows is of a different sort 

 than that raised by currying the cows. The dirt from utensils, from soil, 

 from dung, from the skin of animals and from other sources each has its 

 peculiar character and may be expected to affect milk differently. Wherein 

 does this difference chiefly lie? Not in the dirt itself, but in the bacteria 

 attached to it. Practically all dirt that gets into milk carries its quota 

 of bacteria but some of it is much more heavily seeded with germs and 

 dirt from some sources is more likely than that from others to carry 

 those germs that markedly affect milk, or those that infect people who 

 drink it. So all dirt and all sources of pollution are not of equal im- 

 portance. Bacteria are washed into milk from the dirt that falls into 

 it and much dirt, as for instance manure, partially dissolves; consequently 

 the removal of visible particles by straining or centrif ugalizing does not re- 

 store milk to its original purity, for these operations leave bacteria in the 

 milk. To keep dirt out of milk is comparatively easy but once it is in, 

 to remove it completely is impossible. Milk once contaminated remains 

 so. Therefore, cleanliness at the farm is of the utmost importance, for 

 if it is rieglected there all the pains that are taken with the milk afterward 

 are in part nullified. Since clean milk ordinarily contains but few bac- 

 teria, and milk that has been much exposed to dirt contains many, low 

 bacterial counts of milk at the farm have been widely accepted in 

 the United States as a guarantee of the use of cleanly methods by the 

 dairyman.- 



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