84 MANUAL OF FARM ANIMALS 



nearly every disease has at one time been classed as transmis- 

 sible. In a good many cases, diseases seem to pass from gen- 

 eration to generation with regularity or even certainty and are 

 often classed as hereditary diseases, whereas the facts are that 

 such troubles are germ diseases and are due to infection. 

 Again, there are diseases peculiar to certain conformations, 

 such as a curb or a spavined hock on the horse. The peculiar 

 conformation may be hereditary, and the animal contracts 

 the disease because of the conformation, but the disease as 

 such was not transmitted. The results are the same, but it is 

 best to state it correctly. 



Prepotency is the power that one parent has over the other 

 in determining the character of the offspring. It is usually 

 considered from two points of view; first, " race " or " breed " 

 prepotency, when all the individuals of the race or breed are 

 possessed of such power in transmitting their characters ; and 

 second, "individual" prepotency, when the individual possesses 

 the power to transmit its own characters to the offspring to 

 the exclusion of the other parent. 



Breed prepotency is clearly exhibited when two distinct 

 breeds are crossed, as the offspring will more clearly resemble 

 one breed than the other. Among cattle, the Galloways are 

 noted for being prepotent in color and in the polled charac- 

 ter, for when crossed upon other breeds, the offspring are 

 nearly all black and hornless. The Herefords are prepotent in 

 transmitting their white face to the offspring when crossed on 

 other breeds. 



Individual prepotency is a very great factor in breed im- 

 provement. Many of the modern breeds of farm animals owe 

 their existence to the individual characters of the animal that 

 founded the line. Hambletonian 10 among trotting horses 

 is an example. He sired horses who in turn sired animals of 

 great speed, with the result that most of the Standard Bred 

 horses trace either directly or indirectly to Hambletonian 10. 



