6 -7 



138 Testing Milk and Its Products. 



of a cow may be obtained by making correct weighings 

 and tests of her full day's milk once every thirty days. t| 



163. When to test a cow. 1 The Vermont experiment 

 station for several years made a special study of the 

 question when a cow should be tested in order to give a 

 correct idea of the whole year's performance, when only 

 one or two tests are to be made during the lactation 

 period. 2 The results obtained may be briefly summarized 

 as follows: tl 



a. As to quality of milk produced. If two tests of each 

 cow's milk are to be made during the same lactation 

 period, it is recommended to take composite samples at 

 the intervals given below: 



First sample. Second sample. -3 



For spring cows, 6 weeks after calving. .6 J-7 mos. after calving. 

 For summer" 8 " " " 

 For fall " 8-10 " " " 



If only one test is to be made, approximately correct 

 results may be obtained by testing the milk during the 

 sixth month from calving, in case of spring cows; during 

 the third to fifth month in case of summer-calving cows, 

 and during the fifth to seventh month for fall-calving 

 cows. 



In all cases composite samples of the milk for at least 

 four days should be taken (165). "The test of a single 

 sample, drawn* from a single milking or day, will not of 

 necessity, or indeed usually, give trustworthy results." 



1 H. B. Gurler in American Dairying, p. 18, suggests that three months 

 after calving a cow's milk may be weighed for a week and a composite 

 sample tested. The average weight of butter fat produced per day is cal- 

 culated and this average figure multiplied by 252 or the number of days in 

 8.4 months. It is assumed that a cow gives milk more than 8.4 months 

 and the quantity produced beyond this time will bring the production 

 during the last 2.4 months up to the same average per month as in the 

 first six months. 



2 Sixth report, 1882, p. 106; Ninth report, 1895, p. 176. 



