i36> testing Milkjind Its Products. 



some cows' milk will often change very considerably 

 without any apparent cause. The dairyman who is in 

 the habit of making tests of the milk of his individual 

 cows at regular intervals will have abundant material 

 for study in the results obtained, and he will soon be 

 able to tell from the tests made, if these are continued 

 for several days, whether or not the cows are in a normal 

 healthy condition or have been subjected to excitement 

 or abuse in any way. 



161. Number of tests required during a period of lacta- 

 tion in testing cows. The daily records of the six cows 

 referred to on page 133 give data for comparing their 

 total production of milk and butter fat during one period 

 of lactation, as found from the daily weights and tests 

 of their milk, with the total amount calculated from 

 weights and tests made at intervals of 7, 10, 15 or 30 

 days. The averages of all results obtained with each of 

 the six cows show that weighing and testing the milk of 

 a cow every seventh day gave 98 per cent, of the total 

 milk and butter fat, which according to her daily record 

 was the total product. Tests made once in two weeks 

 gave 97.6 per cent, of the total milk, and 98.5 per cent, 

 of the total butter fat, and tests made once a month, or 

 only ten times during the period of lactation, gave 96.4 

 per cent, of the total milk, and 97 per cent, of the total 

 production of butter fat. 



162. The record of one of the cows will show how 

 these calculations are made: It was found from the 

 daily weights and tests that cow No. 1, in one lactation 

 period of 307 days, gave 5,044 Ibs. of milk which con- 

 tained 254 Ibs. of butter fat. Selecting every thirtieth 



