144 MODERN METHODS OF TESTING MILK 



or by weight alone, whether sold for direct consump- 

 tion or taken to a cheese-factory or creamery. But 

 whenever milk is paid for according to its percentage 

 of fat, as in certain forms of market milk, at cream- 

 eries, at condenseries, and at progressive cheese-fac- 

 tories, the cow producing the largest amount of milk- 

 fat will nearly always be found the most profitable. 

 As a rule, a pound of milk- fat can be produced at less 

 cost in rich milk than in poor milk. The only method 

 of ascertaining accurately the value of a cow or of a 

 herd for the production of milk-fat ic by testing the 

 milk. The real object of a test is to find the total num- 

 ber of pounds of fat produced in the milk for a defin- 

 ite period of time, the most satisfactory unit being one 

 period of lactation, that is, from the time of calving 

 to the time of becoming dry. 



In testing the value of a cow for the production of 

 milk-fat, two factors must be considered : ( i ) The 

 amount of milk produced and (2) the per cent, of fat 

 in the milk. The first amount is obtained by weigh- 

 ing the milk, and the second by testing the milk by 

 the Babcock test. From these data the amount of 

 milk-fat produced is easily found. 



In applying the Babcock test on the farm to indi- 

 vidual cows, certain details need to be considered, 

 such as (i) the duration of the testing, (2) the fre- 

 quency of testing, (3) the method of sampling, (4) 

 weighing the milk, (5) keeping records, and (6) cal- 

 culating results. In carrying out the work of the 

 milk-test, all necessary details are given in Chapter 

 IV, p. 53. 



Duration of testing. — For best results, the tests 



