BROODIXESS AND FECUNDITY IN FOWE 77 



^ij. Correlation Betiveen the Presence of Broodiness and Winter Production 

 above the Mean of Broodies and Xrm-broodies Combined — Pullet Year (Im- 

 proved Flock 1923). 



I I 



^\ inter Production Broody I Non-Broodv 



Coefficient of correlation 4" -l^GS ± .0317 



This constant is of questionalile magnitude and signifies that winter produc- 

 tion of the 1923 flock, above the mean of 53.62 eggs is but little dependent 

 upon tlie presence of the broody trait. The fact should be recalled, however, 

 that the maxinumi winter production (V4.5 eggs) was made by the 1921 flock 

 with 44-.56 per cent of the birds broody during the pullet year. 



The later sections of this report are de\ oted to a consideration of the cor- 

 relation between rate and egg yield and broodiness and eiis: yield. 



27. Correlation Beticeen Winter Rate and Annual Egy Production — Pullet 

 Year. 



In commercial poultry breeding for fecundity, a short-time measure of 

 probable annual production is of vast importance. If the winter rate could 

 be used as a basis for selecting breeding females as efficiently as the yearh' 

 record, it would be of vast economic importance. By making use of the co- 

 efficient of correlation, a measure of the probable worth of tlie winter rate in 

 selecting for large yearly records is obtained. The constants arrived at in 

 this study are given below: — 



Nmnlier of birds ....... 2212 



Mean winter rate ...... 66.41 



Winter rate standard deviation .... =1=9.38 



Mean annual production ..... 174.37 



Annual production standard deviation . . il;44.59 



Coefficient of correlation -[-.4561 ±: .0113 



Tlie mean annual egg production of the 2242 birds used in section 27 was 

 174.37, with a standard deviation of 44.59, or a coefficient of variation of 

 about 25 per cent. The class range in egg production is from 21 to 300 v.ith 

 class intervals of 10. This wide range in production is due to the hetero- 

 geneity of the flock and to the number of characteristics that affect production. 



The magnitude of the correlation coefficient, together with the small prob- 

 able error, suggests that winter rate is rather intimately correlated witli 

 annual egg production. 



28. Correlation Between Annual Rate and Annual Eijij Yield. 



Annual rate as calculated for this flock is a rather concise measure of in- 



