LIMITED TRAPNESTING 13 



LIMITED TRAPNESTING FOR ESTIMATING AGE AT FIRST EGG 



Age at first egg is recognized as having an important association with egg pro- 

 duction. For pullets hatched during March and April, a reasonable approxima- 

 tion of age at sexual maturity may be secured by trapnesting through the month 

 of October. 



Of the total population of 1684 pullets, 1268 or about 75 percent laid some eggs 

 during October. The mean number of eggs laid was 16.6 and the mean age at 

 first egg was 187 days. The correlation between the number of eggs laid in 

 October and age at first egg was —.4619+ .0149, with slight deviation from 

 linear regression. The correlation ratio was .4853. 



The regression of age at first egg on October production is recorded in Table 9. 

 The estimates agree closely with the actual ages. The data indicate that any 

 bird that laid any eggs during October is likely to fall below the limit of 216 days 

 at sexual maturity. It would be reasonably safe, therefore, for the breeder to 

 classify birds that failed to begin laying in October as late in sexual maturity. 



Table 9. — Limited Trapnesting as a Means of Estimating Age at First Egg, 

 C. Regression^ of Age at First Egg on October Egg Record. 



October 



Egg 

 Record 



1 -2 



3-4 



5-6 



7-8 



9-10 

 11 - 12 

 13 - 14 

 15- 16 

 17 - 18 

 19- 20 

 21 - 22 

 23-24 

 25 - 26 

 27 -28 

 29-30 

 31 



1268 

 ' Regression not strictly linear. 



