10 



MASS. EXPERIMENT STATION BULLETIN 359 



A group of 129 females showing 3.10 percent of infertile matings as pullets 

 showed 6.20 percent of infertile matings as yearlings. There were 24 individuals 

 tested for three years with no unsuccessful matings the first two years and 4.17 

 percent failures in the third year. Four females were carried through four seasons 

 without any infertile matings. 



A group of 105 birds was tested first as yearlings and carried through two 

 breeding seasons. There were no infertile matings as yearlings and 8.57 failures 

 as two-year-olds. A group of 22 females began as yearlings and carried through 

 three seasons with no infertile matings. Si.x birds had no infertile matings through 

 three seasons, but as four-year-olds showed 16.67 percent failures. 



These data in general agree with the observations of Jul! (1935). As a rule, 

 fertility of females appears to decline with age. There are many exceptions to 

 this rule, however, and the data suggest that age in females is less important 

 than in males. It seems probable, also, that the male is more important than the 

 female from the standpoint of fertility. 



4. Relation Between Winter Egg Production and Fertility 



'The number of eggs laid from the first pullet egg up to March 1 varies widely 

 in a flock bred for high production. This winter egg record depends upon a 

 number of factors such as hatching date, age at first egg, intensity, and winter 

 pause, as well as upon many environmental influences. For the period from 1922 

 to 1936 the mean yearly egg production ranged from 76 to 104 eggs and the 

 individual range was from 1 to 165. It is desirable to know whether there is any 

 relation between winter egg production and the fertility of eggs laid from Feb- 

 ruary 1 to April 25 of the pullet year. The mean fertility of pullets in the different 

 winter egg production classes is recorded in Table 6. 



Table 6. 



-Mean Fertility of Different Egg Production Classes Includ- 

 ing Zero Fertility 



