452 MANAGEMENT AND FEEDING OF SHEEP 



ing, the more quickly will improvement be effected, when 

 properly mated with prepotent rams, as such dilution of 

 blood elements makes it more plastic, and, therefore, 

 more susceptible to the influences exerted by the more 

 prepotent parent. The exceptions to this rule are found 

 in those instances in which the females are already graded 

 more or less by descent from pure sires of the breed from 

 which these are to be chosen in future breeding. Com- 

 mencing with very common females of mixed breeding 

 and using only pure-bred males in succession of only one 

 and the same breed, in four or five generations, the aver- 

 age of the animals for meat-making should fully equal 

 the average of the breed from which the sires have been 

 chosen. The improvement or change in wool production 

 will be less rapid. Improvement through grading is dis- 

 cussed by the author in Chapter XXVI of the book "Ani- 

 mal Breeding." 



The foundation ewes for grade flocks may usually 

 be obtained at the stock yards, where a very considerable 

 trade is conducted in supplies of sheep for feeding. As 

 a rule they can be more cheaply obtained in autumn. The 

 major portion come from the range. They are generally 

 of mixed blood elements, but Merino blood more com- 

 monly predominates, which is so far a guaranty of rug- 

 gedness. Such ewes are usually healthy, but this fact 

 does not certainly assure the buyer that they are abso- 

 lutely free from parasites. The aim should be to buy 

 ewes whose teeth have not been seriously injured through 

 age. 



Foundation stocks may also be obtained in many in- 

 stances from farmers who are breeders of grade sheep. 

 When thus purchased, the previous history of the flock 

 in relation to disease may be obtainable. The importance 

 of obtaining such information cannot be overestimated. 



The sires used in grade flocks — The sires used in 

 grade flocks should in all instances be purely bred where 

 it is possible to secure them. They should be purely bred, 



