BROODINESS AND FECUXDITY IN FOWL 



Number of birds .... 



Mean total days liroody 



Total days broody standard deviation 



Mean winter rate 



Winter rate standard deviation 



Coefficient of correlation 



2221 

 23..50 



±27.04. 



66.4.5 



±9.37 



+.0178 ± .0142 



The coefficient of correlation is practically the same figure as was obtained 

 between times broody and winter rate. This is also a false correlation be- 

 cause broodies and non-broodies each represent a genetic type. Since winter 

 production and annual production are so intimately correlated (Hervey 1923; 

 Hays, Sanborn and .Tames 1924), high winter record is of very great im]iort- 

 ance in breeding for fecundit}'. 



Blakeman's test for linearity of regression hiis been applied in this study 

 with tlie following results: 



Correlation ratio for days broody . . . -f-.1134 



Correlation ratio for winter rate . . . -(-.169.5 



(Cor. llatio)2^. (Cor. roeff.)2= . . . .007,5 ± .0024 



(Cor. Ratio)2^ (Cor. Coeff.)2=r . . .0233 ± .0043 



The difference lietween tlie corrt-Ialion ratio for winter rate squared and 

 the correlation coefficient squared is .0233 ± .0043, a ditference more tlian five 

 times as great as its probable error. This fact indicates that the coefficient 

 of correlation is false, as might l)e anticipated froni the fact that two genetic 

 races are concerned. 



10. Correlation Between To^al Dki/s Jiroo'l;/ and Winter Rate for Broo'hj 

 Birds- .Hone — Pullet Year. 



Winter rate records are available on 1098 l)irds that were l)roody tlie first 

 year. In this study days broody is tabulated ngainst winter rate to furtlier 

 disco\'er the correlation between degree of broodiness and winter rate. Con- 

 stants are as follows: — 



Number of l)irds 1098 



Mean total days broody 42.85 



Total days broody standard deviation . . . ±27.14 

 Mean winter rate ....... 67.57 



Winter rate standard deviation .... ±9.63 



Coefficient of correlation — .0241 ± .0203 



Regression broodiness on rate .... — .0679 



Regression rate on broodiness .... — .0085 



The coefficient of correlation as sliown above signifies independence between 

 degree of l)roodiness and winter rate. The intensity of the broody trait is 

 therefore of no concern in aflFecting winter intensity. 



20. Correlation Betzceen Total Dai/s Brood i/ and Annual Rate — Pullet Year. 



The total days broody for each Inrd are tabulated against her annual rate. 

 The lowest rate class is 16-20; the highest rate class is 86-90 The lowest 

 broody class is 0-9; the highest broody class is 1.50-159 days. This study on 

 the 2245 birds used in section 11 will show if broodiness is an advantage or 

 disadvantage from the standpoint of annual rate. Are broodiness and high 

 intensity linked together? Constants calculated are:— 



