lp:ngth of biological laying year 11 



IL Annual persistency of daughters from dams with a biological year greater 

 than 365 days is distinctly higher than in daughters from dams with a biological 

 year of from vil5 to 365 days or from dams with a shorter biological year than 315 

 days. 



12. Annual egg records of daughters from dams with extended biological year 

 are superior to those from dams with shorter biological year. 



13. (Treat duration of biological year in dams indicates superior vigor as mea- 

 sured b\' the lower mortality rate for their daughters in the laying houses. 



14. In general, the selection for breeding purposes of females having the ability 

 to lay continuousK- for more than 365 days is a commendable practice. 



References 



Hlakeman, J. 1905. On the tests of linearity of regression in frequency distribu- 

 tion. Biometrika 4:332-350. 

 Hays, F. A., and Ruby Sanborn. 1926. .\nnual persistency in relation to winter 



and annual egg production. Mass. .\gr. Expt. Sta. Tech. Bui. 9. 

 Hays, F. A. 1927a. The inheritance of persistency and its relation to fecundity. 



Proc. World's Poultry Congress pp. 92-95. 

 Hays, F. A., and Ruby Sanborn. 192713. Intensity or rate of laying in relation 



to fecundity. Mass. Agr. Expt. Sta. Tech. Bui. 11. 

 Hays, F. A., and Ruby Sanborn. 1927c. Net correlation of characters concerned 



in fecundity. Mass. Agr. Expt. Sta. Tech. Bui. 12. 

 Hays, F. A., and Ruby Sanborn. 1930. Duration of annual molt in relation to 



egg production. Mass. Agr. Expt. Sta. Bui. 264. 

 Hays, F. A. 1932. Hereditary and environmental factors affecting variability- in 



egg production. Mass. Agr. Expt. Sta. Bui. 289. 

 Hays, F. A. 1933. Relation of body weight and age at sexual maturity, i^oultry 



Sci. 12:23-25. 

 Hurst, C. C. 1921. The genetics of egg production in White Leghorns and White 



Wyandottes. \"I. Natl. Poultry Jour. Oct. 7. 

 Marble, D. R. 1930. The molting factor in judging fowls for egg production. 



N. Y. (Cornell) Agr. Expt. Sta. Bui. 503. 



PUBLlC.\TION OF THIS DOCUME.NT APPROVED BY COMMISSION ON ADMINISTRATION AND FINANCE. 



.^M-6-'33 No. S737 



