440 Pork Production 



Prepotency. 



As understood by the breeder, prepotency is the ability 

 of an animal to impress on his offspring his own charac- 

 teristics to the exclusion of those of the other parent. It 

 is the ability of an individual to " breed on." Because the 

 sire is more depended on than is the dam in live-stock im- 

 provement, prepotency is sought in the sire rather than in 

 the dam. A prepotent sire is the cornerstone of all herd 

 improvement. Prepotency is desirable in the sire used 

 for the production of grade stock and of supreme impor- 

 tance in the head of a pure-bred herd. 



Observations show that prepotent animals are usually 

 the product of rather close breeding, or, in other words, 

 the result of selecting animals within certain clearly de- 

 fined limits of type and breeding. As shown by experi- 

 mental studies, the result of such selection is that the 

 germ-cells produced by the boar or sow will be more alike 

 in their hereditary qualities and, further, that there will 

 be fewer differences between the hereditary qualities of 

 the sperms on the one hand and the eggs on the other. 

 Pigs resulting from the union of such germ-cells will be 

 prepotent when mated with individuals the result of di- 

 verse germ-cells the product of mixed breeding. Line and 

 in-breeding have the practical effect, therefore, of intensify- 

 ing the hereditary qualities and hence of securing prepo- 

 tency in animals so bred. Scrub animals which are the 

 result of scrub ancestry are prepotent in the qualities of 

 the scrub, just as superior specimens are prepotent in their 

 desirable characters. 



Relative influence of the sire and dam. 



As a general rule, it may be said that the sire and dam 

 are equal in the influence which each exerts on the charac- 



