5-Z 



influences, factors, or whatever they may be, to a maximum, the mean l)ody 

 weight should not diminish in an early maturing flock. On the face of it, the 

 major problem here seems to be to discover just what these influences are and 

 to make all conditions optimum for their manifestation. 



Daily Gain versus Days Between 150 Days Old and Age at First Egg 



The degree of importance of the time element in relation to daily gains may 

 be ascertained from the degree of correlation between daily gain and number 

 of days between 150-day age and age at first egg. Records on 814 pullets have 

 been tabulated for studv. The constants derived follow: 



Number of birds 



Mean daily gain ..... 



Daily gain standard deviation 



Mean days between weights 



Days between weights standard deviation 



Coefficient of correlation .... 



814 



.0269 

 ±.0084 

 60.78 

 ±28.12 



-.4145±.0196 



A negative coefficient of .4145 ±.0196 substantiates the opinion that pullets 

 tend to accumulate weight very rapidly just before they begin laying. We have 

 already shown that relative rate of gain is not of much importance in selection 

 for winter fecundity, and that the 150-day weight is just as accurate a basis of 

 selection as rate of gain and entails only half the labor. 



Winter Production versus Annual Production. 



It is important to know the degree of correlation between winter production 

 and annual production since winter egg record may conveniently be used as a 

 basis for selecting pullet breeders. Furthermore, winter record could be used 

 as a basis of culling for high annual records and as a basis for determining the 

 intensity of pullets. Annual records are not yet complete on the flock being 

 studied, consequently the winter record of three previous flocks has been 

 tabulated against their 365-day record. A total of 845 individuals hatched in 

 1920, 1921, and 1922 have been studied. Constants have been calculated as 

 follows : 



Number of birds .... 



Mean winter production . 



Winter production standard deviation 



Mean annual production 



Annual production standard deviation 



Coefficient of correlation . 



845 



70.26 



±25.07 



193.95 



±40.25 



-f-.6214±.0142 



The above coefficient shows that in approximately six cases out of ten high 

 winter record is directly associated with high annual record. In other words, 

 selection for annual egg yield would be about sixty per cent accurate if made 

 on winter trap-nest records alone. This fact makes very evident that winter 

 egg record is of very great importance in its relation to annual record and that 

 it is of great value in selecting pullet breeders. 



In previous sections the relative importance of different measurable char- 

 acteristics in relation to winter production has been discussed and the degree 

 of correlation calculated in each case. These findings help to make clear why 

 winter egg record as determined on a calendar basis is subject to wide variation 

 aside from the variation caused by hereditary factors known to affect it. Such 

 facts being known, the difficulty and uncertainty of properly classifying the 

 pullets in distinct genotypes becomes very apparent. Such variables as have 

 been considered must be reduced to a minimum in order to make proper matings 

 for purposes of reducing genetic variability to a minimum. When the genetic 

 nature of each breeding bird is discovered, definite types of matings may be 

 made and progress assured. There can be no short road in the establishment 

 of a flock breeding true for high winter fecundity. 



