Milk Yield of Cows. 



219 



Agricultural Experiment Station in New York in 

 a recent bulletin. Records have been kept of the 

 milk yields obtained from the University herd during 

 the seven years 1891-98. This herd, which consists of 

 about twenty cows, mostly Jerseys and Holsteins, has been 

 developed from the ordinary stock of the neighbourhood by 

 the use of thoroughbred bulls and a rigid selection of the 

 best heifers. This course of breeding was established 

 in 1875 and has been continued ever since ; and the succes- 

 ful results of the care bestowed on their selection may be 

 judged from the fact that in 1875 the average yield of milk 

 per cow was little more than 300 gallons, whilst the 

 descendants of these same cows produced an average of 

 750 gallons in 1897-98. 



The cows are bred, so far as possible, to calve during the 

 early autumn, and they are milked for about ten months, 

 most of them being dry during July and August. In summer 

 they are kept at pasture, which is supplemented when neces- 

 sary with green forage ; in winter they are stabled, but 

 have access during the day to a covered yard. The average 

 milk production of the cows for each year is given in the 

 following table : — 



Year. 



1891- 2 - 



1892- 3 - 



1893- 4 - 



1894- 5 - 



1895- 6 - 



1896- 7 - 



1897- 8 - 



An examination of the records of all the 135 cows made for 

 the purpose of determining the average rate of decrease in 

 yield of milk as the period of lactation advances, and also 

 the average increase in the percentage of fat during the same 

 time, shows a gradual and fairly regular decrease in milk 

 flow from the time of calving until the cow is dry. With 

 regard to the percentage of fat, the records show a decrease 

 from the first month to the second, and then a gradual rise 



Number of 

 Cows. 



Age. 



Gallons of 

 milk per 

 Cow. 



Average 

 percentage of 

 fat. 



19 



4-0 



7i6'34 



3 '94 



17 



4'6. 



687-50 



3 '93 



19 



4*5 



756-33 



3-86 



22 



4-8 



716-29 



377 



19 



4-2 



745 " 62 



3"57 



20 



4 -2 



749-54 



3-62 



19 



47 



757-53 



3-68 



