134 



POULTRY PRODUCTION 



conductor that makes possible in production tlie possibilities 

 generated in breeding. 



There must be ph> sical thrift to withstand the exhaustion 

 of an iidierited heavy production. Reproduction in the hen 

 is normal only when there is an ex'cess of vitality, as well as 

 of feed, beyond that needed for the hen herself. In the case 

 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, 



Fi.i. 66 



ShovviiiE the (lillurence in the olTapring of strong and weak hens. These 

 chicks had the same sire. (Courtesy of Kansas .^Ki'icultural Experiment 

 Station.) 



out of which growth is manufactured. This can only be had 

 when e\'ery organ of digestion and assimilation and of re])ro- 

 duction is large and active. Such organs can e.xist only in 

 a capacious ))ody and capacity is a first recjuisite of ^'igor. 



Beyond this it is a law of universal application that low 

 vitality means weak defensi\e agencies throughout the body 

 and a greater suscei)tibility to disease. This extends not 

 only to the in(li\'idual, but to the offspring by way of inherit- 

 ance and b\' lessening the bactericidal projterties of the 

 secretions of the oviduct during the niaiiuFacture of the egg. 



A good constitution is as nuich a heritable character as are 



