r ^70 ] 



XXXV. 



THE SEPARATE INHERITANCE OF QUANTITY AND 

 QUALITY IN COWS' MILK. 



By JAMES WILSON, M.A., B.Sc, 

 Professor of Agriculture in the Royal College of Science, Dublin. 



[Eead May 24. Ordered for Publication June 14. Published July 28, 1910.] 



It is a very general opinion that the milk of high-yielding cows is usually 

 poorer and tliat of low-yielding cows richer in quality. The origin of this 

 opinion lies, perhaps, in the fact that some breeds, like the Dutcli, tliat are 

 at the top of the scale with regard to quantity, are nearer the bottom witli 

 regard to[,quality; while others, like tlie Jersey, that are at the top with 

 regard to quality, are lower down with regard to quantity. No one denies 

 tliat there are many exceptions to the rule, but these exceptions are generally 

 regarded as departures in some degree from the normal. At the same time 

 it would be difficult to find any cautious writer vehemently dissenting from, 

 or assenting to, the general opinion, for the reason that, till recently, no large 

 body of data bearing upon tlie question had been brought together. Now, 

 however, in the " Report of Milk Records for Season 1908," recently published 

 by the Ayrshire Cattle Milk Records Committee, we are furnished with data 

 from which it is possible to obtain a ruling. 



The systematic milk-testing scheme for Ayrshire cattle, the inception and 

 success of which are almost entirelj'due to the late Mr. John Speir, Kt. St. 0., 

 of Newton, near Glasgow, was inaugurated in 1903 ; and 1342 cows were 

 tested in that year. The records of 8132 cows are contained in the report 

 for 1908. The scheme is worked as follows : — The Ayrshire cattle country is 

 divided into districts each containing either about ten or eleven or about 

 seventeen or eighteen farms coming under the scheme. To each district is 

 appointed a trained official whose duty it is to visit all his farms in rotation. 

 If tliere are eleven farms in his district, he can visit each of them once a 

 fortnight ; if tliere are eighteen, he can visit each once every three weeks. 

 The official reaches a farm in the afternoon, stays over niglit, and leaves next 



