BREEDING 



129 



of persistent and continuous reproduction there must be a 

 very large excess. 



In order to realize on an inherited tendency to quick 

 growth and early maturity, there must be good digestive 

 power to prepare for assimilation large amounts of materials, 

 out of which growth is manufactured. 



Beyond this it is a law of universal application that low 

 vitality means weak defensive agencies throughout the body 

 and a greater susceptibility to disease. This extends not 

 only to the individual, but to the offspring by way of inherit- 

 ance and by lessening the bactericidal properties of the 

 secretions of the oviduct during the manufacture of the egg. 



Showing the difference in the offspring of strong and weak hens. These 

 chicks had the same sire. (Courtesy of Kansas Experiment Station.) 



A good constitution is as much a heritable character as are 

 color and comb. Proper housing, feeding, incubating, and 

 general care help to conserve the health of the flock, but the 

 very best management cannot obviate the necessity of a 

 vigorous fowl to begin with. It is "bred in the bone," and 

 handed down to offspring from both parents. 



Influence of Vigor of Bam upon Offspring. — ^Aside from 

 the question of the inheritance of vigor lies the fact that 

 only the complete health and nourishment of the body is 

 likely to insure the highest vitality and, in the case of the 

 males, activity in the reproductive cells. Furthermore, 

 9 



