BREEDING 137 



ment of the general farm. For improvement in this quaUty, 

 great as is its importance, the ordinary producer must depend 

 upon the breeder, seeking it through the medium of grading. 



Heavy Production and Hatching Power. — The question of 

 whether high fecundity tends to lessen hatching power or 

 not is one upon which opinion varies and upon which there 

 is comparatively little evidence. Rogers^ reports on work 

 with eighty-two hens in which all the eggs incubated during 

 the second season were used. He found that taking the 

 two years' production as a basis of comparison the hatching 

 power was higher with average producers than with those 

 individuals whose production was exceptionally high or 

 exceptionally low. 



The hen that lays large numbers of eggs appears to slight 

 them somewhat from the physiologic stand-point. Beyond 

 a certain limit, increased egg production is obtained only at 

 the expense of hatching power. . 



On the other hand, with the hen that produces an unusually 

 small number of eggs, lack of vitality is likely to be the limit- 

 ing factor which affects the hatching power as well as the 

 production. 



Bearing on this same point. Pearl and Surface^ reached 

 the conclusion that "there is a distinct correlation between 

 winter (November to March) egg production and the per- 

 centage of fertile eggs hatched during the subsequent breed- 

 ing season. This correlation is of such sort as to indicate 

 that in general the higher the winter egg production of a 

 particular bird the lower will the percentage of that bird's 

 fertile eggs hatched probably be, and vice versa." 



Rate of Production and Hatching Power. — ^There seems 

 also to be a relation between the rate of egg production 

 during the incubating season and hatching power. As 

 shown by Table No. XV, hens laying eleven eggs or less 

 during the same period that other hens were laying 19 or 

 more, were credited with a 17.3 per cent, greater hatch, con- 

 sidering all eggs that were set. 



' Cornell Countryman, vol. ix, No. 3. 

 2 Maine Bulletin No. 168. 



