LENGTH OF INCUBATION PERIOD 



Table 7. — Relation of Length of Incubation Period to Egg 

 Production 



The data are rather limited, but they show a consistent dechne in mean annual 

 egg production as the length of the incubation period increased. There was a 

 difference in annual egg production of about 55 eggs between the very early 

 emergmg pullets and the very late emerging pullets. In view of this fact, it would 

 seem advisable for breeders to breed selectively for early emergence of chicks 

 from the shell, and information regarding possible hereditary factors that may 

 influence time of emergence would be very useful. 



Annual Persistency 



High persistency is vitalh' important from the stan dpoint of maxinmm egg 

 production in any flock; hence it is desirable to ascertain whether persistency 

 bears any relation to the length of the incubation period. Table 8 presents the 

 mean persistency of birds in the seven different emergent periods. 



A rather consistent decline in persistency may be observed as the length of the 

 incubation period increased. There was a decline of about 25 days in the length 

 of the production year in the birds of group 7 as compared with group 1. It 

 seems probable, therefore, that earlier emerging birds are likely to be somewhat 

 more persistent layers than late emerging birds. 



Table 8. — Relation of Length of Incubation Period 

 TO Annual Persistency 



Emergent Period 



Number 

 of Birds 



Mean Annual Persistency 

 Days 



