Testing Milk on the Farm. 143 



On July 17, 1893, the mixed milk of the Jersey cows 

 tested two-tenths of one per cent, higher than on the pre- 

 ceding day; the Guernsey herd milk tested one- tenth of 

 one per cent, lower, while the Shorthorn milk did not 

 change in composition; comparing the tests on July 19 

 and 20, we find that the Jersey and Shorthorn milk tested 

 four- tenths and one- tenth of one per cent, higher, respect- 

 ively, on the latter day than on the former, and the 

 Guernsey milk tested one-tenth of one per cent, lower. 



169. Ranges in variations of herd milk. According to 

 Fleischrnann, 1 the composition of herd milk may on single 

 days vary from the average A^alues for the year expressed 

 in per cent, of the latter, as follows: 



The specific gravity (expressed in degrees) may go above or 

 below the yearly average by more than 10 per cent. 



The per cent, of fat may go above or below the yearly average 

 by more than 30 per cent. 



The per cent, of total solids may go above or below the yearly 

 average by more than 14 per cent. 



The per cent, of solids not fat may go above or below the 

 yearly average by more than 10 per cent. 



To illustrate, if the average test of a herd during a whole 

 period of lactation is 4.0 per cent., the test on a single day may 

 exceed 4.0+ T 3 o% X 4.0 = 5.2, or may go below 2.8 per cent, (viz., 

 4.0 T 3 X 4.0); if the average specific gravity is 1.031 (lacto- 

 meter degrees, 31 2 ) the specific gravity of the milk on a single 

 day may vary between 1.0279 and 1.0341 (31 + ^ X 31 = 34.1; 

 31- T 'o X31 = 27.9). 



170." Influence of heavy grain-feeding on the quality of 

 milk. If cows are not starved or underfed, an increase 

 in the feeding ration will not materially change the rich- 

 ness of the milk produced, as has been shown by careful 



1 Book of the Dairy, p. 32. 



2 See page 94. 



