ANNTAl. rKIJSISll-,N( ^ AND KCICI I'HODUCTIOxX 



10.5 



(xt nines iiro (>7 ;ind 366 cl;iys, rtsprctivrly. The sliindiird deviation for per- 

 sistenev is very large and indicates tliat a nuniher of faetors is concerned. 



'riie negative ciKnicient of correlation is of siicii niiiiiiiitudc as to suggest an 

 intimate relation between age at first egg and annual persistency. Those 

 pullets that lay at an early age ajipear to he nuuh more persistent layers 

 than those maturing later. Herein lies a partial explanation of the significant 

 iclation between early maturing and high annual production. These studies 

 point to age at first egg as a criterion of importance for i)redicting per- 

 sistency. 



4. Correldtiun Belxaeen Aye al First E(j(j Deloxv the Mean and High Per- 

 sistency. 



The population has again been di\ ided into the two possible genetically dif- 

 ferent classes for persistency as in section 2. These classes have been tabu- 

 lated against age below the mean and age above the mean as follows: 



Age at First Egg 



I 

 High Persistency | Low Persistency 



Below ))ojnilatii;n mean 



860 



387 



Above population mean 



276 



656 



Totals 



1136 



1043 



Coefficient of correlation 



.6816±.0077 



A very intimate correlation is shown by the above coefficient between early 

 sexual maturity and high persistency. This relationship is very significant to 

 the breeder, disclosing possible genetic linkage between two desirable inherit- 

 ed traits that may later be cleared up on a factorial basis. 



5. Correlation Betzceen Weight at First Egg and Annual Persistency. 



Body weight is a convenient standard to use for selection purposes. Weight 

 in poultry is inherited on a multiple factor basis according to Punnett and 

 Bailey (1914). If weight should prove a criterion of persistency, its value 

 for culling purposes soon after pullets begin to lay is very evident. Weight 

 records are available on 2125 of the birds being studied, and when correlated 

 with persistency give the following constants: 



Xuniber of birds 

 Mean weight at first egg . 

 Weight standard deviation 

 Mean annual persistency . 

 Persistency standard deviation 

 Coefficient of correlation . 

 Regression weight on persistency 

 Regression persistency on weight 



2125 

 5.58 

 ±.75 

 302.64 

 ±58.00 

 — .3225±.0131 

 —.004 

 —25.002 



