DAIRYING 



219. Results similar to this were reported in Bulletin 122 of 

 the West Virginia Agricultural Experiment Station in which 

 mixed Holstein and mixed Jersey milk were skimmed, with the 



following results : 



It is a well known fact that the fat globules in Holstein milk 

 are much smaller than in Jersey milk and the difference in the 

 per cent, of fat in the skim milk here given is undoubtedly caused 

 by this fact. 



220. The effect of agitation of the milk is to break up the 

 fat globules into smaller ones, and thus reduce the skimming 

 efficiency. Cream will not rise on milk that has been transported 

 either by rail or by wagon nearly as well as it will on the same 

 milk before this agitation. And heaters used for bringing milk 

 to a skimming temperature for centrifugal cream separation should 

 not agitate the milk violently. This is shown by the following 

 experiment. Milk was churned for five minutes in a churn having 

 a dasher, at different temperatures, and it was found that the 

 churned milk always left more fat in the skim milk than the un- 

 churned. The effect of the churning increases with the temper- 

 ature of the milk. 



Temperature of milk 87 F. 122 F. 185 F. 



Milk not churned 13 .12 .13 



Milk churned before separated... .14 .69 .72 



The influence of agitation on the rising of cream when milk 

 is allowed to stand for some hours in pans or cans is much 

 greater than when milk is skimmed by a centrifugal separator. 



