FERTILITY IN RHODE ISLAND REDS 9 



male. There were 54 females that began the breeding season laying infertile eggs 

 and that were later mated to a different male. Almost 93 percent of these females 

 began to produce fertile eggs after the introduction of the second male. Even 

 though temperature conditions were more conducive to fertility at the time the 

 second male was used, the data suggest that in the majority of cases the male 

 was responsible for infertility and that a change of males was very effective. 

 Two females that were fertile became infertile with a change of males; and 80 

 females were fertile with both males. A change of males was not made because 

 of infertility in these cases. 



In the early-hatched group, the number of infertile matings when the male 

 was not changed rose to 10.59 percent. There were 23 females that began the 

 breeding season laying infertile eggs. A change of males was followed by 91 

 percent laying fertile eggs. Here again is evidence that the male was very likely 

 responsible for the infertility. In this group 6.32 per cent of the females were 

 fertile with both males. 



The combined data show that out of 1,775 matings, 174 females (9.8 percent) 

 started the breeding season laying infertile eggs. An attempt was made to over- 

 come this infertility in 77 cases by a change of male, and in 71 matings of the 77 

 a change in male was followed by fertility. 



Constancy of Fertility in Fe;inales 



Jull (1935) reported that fertility in Leghorn, Rhode Island Red, and Crossbred 

 females was highest in the pullet year and that it declined in the yearling and in 

 the two-year-old. His birds were mated to cockerels in all cases. In our data 

 females that were bred from for more than one year are considered. The age of 

 males used ranged from cockerels to three-year-olds. The data are summarized 

 in Table 5. 



Table 5. — Fertility of Females Used for More than One Year 



Began as Pullets Began as Yearlings 



Classes of Females ■ -~~ 



Number Percentage Number Percentage 



of of of of 



Females Failures Females Failures 



Used for two years: 



First year 129 



Second year 129 



Used for three years: 



First year 24 



Second year 24 



Third year 24 



Used for four years: 



First year 4 



Second year 4 



Third year 4 



Fourth year 4 



