DAIRY FARMING DAIRYING, 721 



DAIRY FARMING— DAIRYING. 



Investigation of the milk of 97 East Friesian cows from 7 herds 

 in East Friesland as to the yield and fat content during one period 

 of lactation, N. WYcnaiiAiVi {Bremen: M. IfeinsiKs Xncli/ohjer, 18!)7, 

 pp. 52; ahs. in Milch Zt{/.,45 {1896), Ko. 48, p. 704). — This investigation 

 \ras made under the auspices of the East Friesicin Breeders' Associa- 

 tion. The Association selected the 7 herds for investi,iintion. Samples 

 of the mixed milk for one day were examined t\A' ice each month, the 

 Gerber test being used. A large amount of tabulated data is given, 

 arranged to show the fluctuations in the yield and fat content of the 

 milk of individual cows as influenced by the stage of lactation, age, 

 pasturage, and other conditions. The averages for the 7 herds were as 

 follows : 



Average yield and fat content of milk from 7 herds during one period of lactation. 



The relation between specific gravity and solids of milk, 

 S. M. Babcock ( Wisconsin Sta. Bpt. 189.5, pp. 120-126).— In the Annual 

 Report of the station for 1891 (E. S. E., 4, p. 189), the following formula 

 is given : 



(IQQg -f g \ 



^QQ -. Qy-Q f g — 1 j (100 — f ) 2.6 



in which S = specific gravity of milk and f = percentage of fat. 



From data accumulated the author now believes the constant 2.G to 

 be too large for the average milk of this country and that it should be 

 reduced to 2.5, and he recommends the substitution of this in the above 

 formula. 



"In this formula it is assTimed that the difference between the specific gravity of 

 milk serum and that of water is directly proportional to the percentage of solids in 

 the serum. This assumption is not quite correct and would lead to a slight error if 

 the solids of the milk scrum were always of the same composition, for in such case 

 the specific gravity of the milk serum and the percentage of solids wliich it contained 

 would change at different rates. . . . 



"The error, however, from this source, with normal milks containing from 8 to 10 

 per cent of solids-not-fat, is small, auiounting in no case to as much as O.Of) per cent, 

 and this I believe is, in most cases, offset by changes in the composition of the milk 

 Bolids. If there is no compensation of this kind the formula should in general give 

 results too low with milks having less than the average percentage of solids in the 

 serum and too higli when tliese solids are above the average. I have not found this 

 to be the case, as in a large number of comparative determinations with milks 



