124 AGRICULTURAL RESEARCH AND THE FARMER ! 



Research Institute on the question of the " heat " periods in 

 cows, and it was shown that one of the main reasons why farmers 

 are often unable to get their cows to the bull at any particular 

 period is that the period of heat is sometimes so short as to be 

 overlooked in ]>ractice. It is hoped that the Cambridge workers 

 will before long be able to furnish information to the farmer 

 which will enable him to mate his cows at any period. This 

 work has a close bearing on an enquiry that has recently been 

 made at Reading into the yield of milk from cows calving in differ- 

 ent months in the year. The enquiry has involved the examina- 

 tion of over 4,000 milk records of cows of three or more calves. 

 The main source of information has been the records of the Berk- 

 shire Milk Recording Society — but particulars have also been 

 obtained from other counties, and the results may be fairly said 

 to cover most of the systems of management adopted in this 

 country. The main facts emerging are that in the case of the 

 cows calving during the winter (October-February), the milk 

 yield per lactation period is from 50-75 gallons higher than that 

 given by cows calving during the summer. In the case of cows 

 of high milk-yielding capacity, it appears that the highest yield 

 will be obtained if they calve in October or November. Cows 

 of average milk-yielding capacity, however, give the highest 

 yield if they calve in December, January or February. In other 

 words, the date of calving should be timed so that the cow's 

 inherent tendency to produce milk will maintain a high daily 

 output from calving until the advent of early summer grass 

 brings about a second " flush " of milk. 



The enquiry has also extended to the milk-yields of cows of 

 different ages. About 3,000 records have been examined in 

 this connection, nearly all of them being from cows of the Dairy 

 Shorthorn type. The average yield from 1,143 first-calf cows was 

 5,645 lb. The yield increases with each lactation period with 

 marked uniformity ; rising gradually to an average of 7,985 lb. 

 obtained from 137 sixth-calf cows. This increase, however, is 

 not due solely to advancing age, for the taking of milk records 

 often results in the drafting out of poor milkers. An attempt is 

 now being made to eliminate this factor and thus get an accurate 

 measure of the increase in milk yield due to age, and at the same 

 time to secure information as to the milk yields of the same cows 

 during successive lactation periods. 



Breeding. — Are good dairy qualities inherited ? To this 

 question, which is of vital importance to the dairy industry, 

 only a very qualified answer can be given, and the answer is 

 chiefly of value in showing the lack of our present knowledge 



