124 ELEMENTARY AGRICULTURE 



sweet lies in preventing the bacteria from getting 

 into it. 



Selection of the Herd. Next in importance to the 

 care of the milk comes the selection of the herd. Since 

 most creameries and cheese factories now pay by the 

 test that is, pay for the amount of butter- fat that 

 the milk contains it is important to the dairyman that 

 his milk tests well, and that his cows give a reasonably 

 large flow of milk. In general, no cow is profitable to 

 the dairyman whose milk tests much less than 3 per 

 cent of butter-fat. Neither is one which gives less 

 than twelve pounds of milk daily, no matter how rich 

 it is. Every farmer should own a small Babcock tester 

 and test every cow in his herd. Such a tester, with 

 directions and complete outfit for testing milk, can be 

 bought for six or seven dollars. Each cow in the herd 

 should be tested, her milk carefully weighed and her 

 dairy value figured out. All unprofitable cows should 

 be disposed of. The best cows in the herd may then 

 be kept for breeding purposes. In this way the herd 

 will be greatly improved and dairying made much more 

 profitable. 



Experimental Study of Milk. 



In all comparisons of milk, samples should be taken 

 under the same conditions and set at exactly the same 

 depth. Test tubes are most convenient for experi- 

 ments with milk. If bottles are used they should be 

 tall and slender, and as nearly the same size as pos- 

 sible. Sample bottles should never be filled above the 



