244 THE BREEDING OF ANIMALS 



a race of animals that will breed true. It matters not how 

 many good qualities the individual breeding animal may 

 possess; if he cannot transmit these good qualities to 

 his offspring, he is not a desirable animal for breeding 

 purposes. He may be valuable for commercial purposes. 

 Such an animal might be a fast horse, a prize-winning 

 beef animal, or a great producing cow, but lacking the 

 ability to transmit these qualities this animal would not 

 be a desirable or valuable individual in a breeding herd. 

 It may be quite possible, therefore, for a method of breed- 

 ing to have a distinct economic value for the production 

 of commercial animals and at the same time be a very 

 bad method for the breeder of improved live-stock whose 

 purpose is to produce animals for breeding purposes and 

 not for slaughter or work. What effect does cross-breed- 

 ing have on the breeding powers of the domestic animals ? 

 What value, if any, has cross-breeding in the production 

 of animals for commercial purposes and which are not 

 intended to be used for breeding ? The breeder's interest 

 in cross-breeding will naturally center about the relations 

 of this practice to heredity. 



227. Advantages from cross-breeding. Breeders of 

 the domestic animals have frequently practiced cross- 

 breeding in the belief that certain very definite and specific 

 benefits followed such practice. In attempting to analyze 

 the reasons for practicing cross-breeding, it is apparent 

 that this has been generally followed for one or more of 

 the following reasons, to increase fertility, to restore 

 weakened constitution, to increase the size or for improve- 

 ment. 



228. Grading. The practice of grading, by which 

 is meant the improvement of native or unimproved ani- 

 mals by mating with pure-bred or registered animals, 



