THE BREEDING OF ANIMALS, IN GENERAL 85 



Again, the breed of American saddle horses owes much of its 

 excellence to the individual prepotency of Denmark. The 

 families of the various breeds of farm animals that owe their 

 existence to the individual prepotency of the animal that founded 

 them are almost without number, such as the St. Lambert 

 family descended from Stoke Pdgis, 1259, and the Eurotas family 

 descended from Eurotas, 2454, among Jerseys; the Johanna 

 family descended from Johanna, 1421, and the De Kol family 

 descended from De Kol 2d, 734, among Holsteins ; the Perfec- 

 tion family descended from Chief Perfection, 32144, and the 

 Corwin family descended from Tom Corwin 2d, 2037, among 

 Poland China swine. 



Since prepotency is of so great importance in improvement 

 among farm animals, those influences that tend to produce it 

 in the individual are worthy of note. While many of the 

 factors surrounding prepotency are not well understood, yet 

 those that do aid and are under the control of man are : purity 

 of breeding, strong constitutional development, and in-breeding. 

 Purity of breeding strengthens prepotency in individual as well 

 as in the breed or race. It strengthens prepotency because it 

 makes for stability. The introduction of outside animals 

 becomes a disturbing factor in the stabihty of the characters of 

 the individual and therefore a disturbing factor in the cer- 

 tainty of transmission. On the other hand, each generation of 

 pure breeding adds to the stability of the type and to the cer- 

 tainty of transmission. 



Vigor in the individual is a very important factor when 

 selecting for prepotency. This is sometimes lost sight of, as 

 in selecting hens for high egg production when nothing but 

 production is considered, and always with serious results, for 

 without vitality all else will fail. 



In-breeding aids prepotency, for it strengthens dominant 

 characters. The more inbred the animals the more intense 

 their power of transmission. This applies, however, to good 



