96 Scientific PmceeiUngs, Royal Dublin Society. 



giving 800 gallons and over during a normal lactation. In the following 

 years these did not all increase in their yields so regularly as the others ; some 

 even fell back the next year ; but such as remained productive till they were 

 five or six years old rose to the 1,000 gallon stage or over. In these cases, it 

 is a fair suggestion that they probably overdid themselves by milking too 

 long as three-year-olds, and did not recover sufficiently to give their full 

 3'ield in the next lactation or even in the next again. 



The estimate also was substantially confirraed for the higliest class cows 

 by the reports of the milking trials of the last twelve London dairy shows. 

 At tliese shows the cows are milked two days, and the average yield for one 

 day is calculated from the total : due allowance being made for cows that are 

 more than sixty days calved. Most of the cows exhibited are of the highest 

 class. The few that are otherwise have been eliminated. The following 

 table shows the rate of increase. It should be noted that there has been no 

 class for three-year-old cows till recently, consequently their niimbers are 

 small, and that few four-year-olds have been exhibited because they have 

 had to compete with mature cows. The few cows that have been exhibited 

 over ten years old are no doubt abnormally good ones. 



Having discussed the most important circumstances that may have to 

 be taken into account in estimating a cow's normal yield at maturity, we can 

 now consider the manner in which the capacity for yield is passed on from 

 one generation to another. First of all, we shall show that improvement, 

 or the reverse, is not gradual, but abrupt and sharp : that if a daughter is 

 not on an approximate equality with her dam as a milk-producer, she is 

 either much higher or much lower. 



This can be shown by quoting the yields of the cows entered in the first 

 volume of the red Danish herd-book along with those of their dams, grand- 

 dams, and so on, where such are known. In this herd-book the cows' ages, as 

 Vejl as the dates at whicli their calves were born, are nearly always given. 



