THE BREEDING OF ANIMALS, IN GENERAL 95 



and intensified them by in-breeding, and in a few generations 

 have succeeded in building up the best herds in the breed. 



Breeding from the best. — The advisability of breeding from 

 the best depends on the situation. When one is grading, it is 

 advisable to procure the very best obtainable. On the other 

 hand, when one is building up a pure herd, it is equally import- 

 ant to give due regard to the strain with which one is working. 

 That is to say, in actual practice the breeder who breeds from 

 the best without regard for blood lines is likely to bring to- 

 gether a confused herd, out of which nothing of note can be 

 established. Crossing family lines brings about much the same 

 condition as crossing the breeds, only on a more limited scale. 



From this it must be apparent that if one is to secure the best 

 results from any system of breeding whatsoever, he must have 

 due regard for ancestral lines. He must keep the strains pure, 

 intensify the desirable characters, thus increasing prepotency 

 and securing uniformity. If the purpose is herd improvement, 

 grading is practicable, as it is a cheap, quick, and conserva- 

 tive method, and if persisted in for a few generations, develops 

 animals about equal to pure breds for production. If the pur- 

 pose is breed improvement, then line-breeding or even in- 

 breeding will be found to be most effective, for by these 

 methods the ancestral lines can be kept true. 



