22 



DAIRYING 



Variation in the Daily Weight and Test (per cent, fat) of Milk 

 of Two Cows in the Same Herd.* 



A glance at these figures shows that the per cent of fat in the 

 milk of cow No. I varied considerably more from one day to 

 another than that of cow No. 3, even though they were fed and 

 handled in the same herd. 



B. Lactation Period. 



168. The time between the calving or "freshening" and the 

 "drying up" of the milk flow of a cow is called her period of 

 lactation. This comes usually within one year, but the length 

 of one period of lactation varies with different cows: it is in- 

 fluenced, first, by the natural characteristics of the cow, second, 



* 111. Bui. No. 24. 



