308 A STUDY OF FARM ANIMALS 



brown, and all the solids in the milk excepting the butter- 

 fat are destroyed. If this small bottle containing the milk 

 sample is then placed in a well balanced centrifugal machine 

 made for the purpose, and is turned for five minutes, the 

 fat is thrown to the surface of the fluid. Hot soft water is 

 then placed in the sample bottle, until it reaches the neck, 

 after which it is rotated in the centrifugal two minutes 

 longer. Then more hot water is added, to fill the neck high 

 enough to permit reading the per cent of fat, which accumu- 

 lates as a solid column when the bottle is whirled a minute 

 more in the centrifugal. One usually measures the fat by 

 use of common dividers, setting the points at the lower and 

 upper line of fat, after which one point is placed at the 

 mark, while the other point indicates the per cent of fat in 

 the milk. The fat should always be measured while hot, 

 before it has contracted by cooling. Every dairy farmer 

 should have a Babcock test outfit, and carefully test the milk 

 of his herd. 



Cow-testing associations have assumed much impor- 

 tance in the United States in recent years. The first asso- 

 ciation of the kind is said to have been established in 

 Denmark in 1895,* while the first one in America was organ- 

 ized in 1905 at Fremont, Michigan. In 1921 there were 

 452 of these associations in the United States, with Wiscon- 

 sin in the lead with 103, Pennsylvania second with 45, and 

 Ohio third with 35. The purpose of the cow-testing associa- 

 tions is to secure disinterested records of the individual cows 

 in the herds of a community. A group of farmers form a 

 co-operative association, adopt rules for conducting the tests 

 of herds and employ an expert or official tester to supervise 

 the work. This person visits each- herd at least once a 

 month, when he weighs each milking of the day, and takes 

 samples of the milk, which he properly tests. He may also 

 make a record of the kind and amount of food fed on the 

 day in question. Unless two small herds are close by, in 



*Farm Dairying, By C. Larsen, 1919. 



