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 
Fic. 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 
