SYSTEMATIC IMPROVEMENT OF ANIMALS 187 



standard, then it would be at once necessary to keep records, 

 and the animals so handled would be no longer mixed bred but 

 would be on their way to becoming a new strain of pure breds. 

 • 2. Pure breeding, in which only registered animals are used. 

 This system has the advantage of securing the best results, but 



Fig. 28. Choice feeding steer, $6.25 per hundredweight (1910) ; usual 

 price, $4.50 per hundredweight 



From " Beef Production," by Mumford 



it is relatively costly, especially with horses and cattle, but less 

 so with the smaller and cheaper animals. 



3. Grading, in which the sire is pure bred, but the dam is 

 not. This system combines the advantages of both preceding 

 methods. It is but little more costly than the first, and is, for 

 practical purposes, almost as effective as the second. 



4. Crossing, in which the sire is of one breed or set of blood 

 lines, as Shorthorn, and the dam of another, as Jersey. This 

 method combines the disadvantages of both the first and second 

 methods in that it is as costly as pure breeding and in the end 



