FERTILITY IN RHODE ISLAND REDS 15 



freezing, fertility ranged from 70 to 85 percent. With weekly hatches over an 

 eleven-week period, fertility rose consistently until the outside temperature was 

 about 37°. 



2. Males had their maximum fertility as cockerels and showed a marked 

 decline in fertility each succeeding year. Females had their ma.ximum fertility 

 as yearlings and exhibited a less marked decline in fertility in succeeding years 

 than did the males. 



3. The percentage of fertile mates for the males used each year remained 

 essentially unchanged through fifteen years. This fact tends to discredit the idea 

 that fertility is governed by inheritance, because indirect selection for high fertility 

 was constantly practiced. The percentage of males having a fertility record of 

 61 percent or more remained unchanged throughout the experimental period. 



4. Males appeared to be responsible for infertile matings in most cases, 

 because a change of males resulted in 93 percent of the infertile matings becoming 

 fertile. 



5. Females did not show a constant fertility from year to year but were likely 

 to e.xhibit declining fertility' after the yearling age. 



6. The number of eggs laid by pullets up to March 1 had no significant effect 

 on their fertility record. 



7. A range from 1 to 14 in the number of females mated to each male had no 

 effect upon the fertility record of the males. 



8. The percentage of infertile matings fluctuated considerably during the 

 period but showed no definite trend. 



9. Mean fertility, obtained by taking the average of the individual female 

 records, had no definite trend in fifteen years. 



10. Fertility was highest when outside males were mated to Station females. 

 From inbred matings fertility was higher than from check matings, except when 

 sires were mated to their daughters. The percentage of unsuccessful matings 

 was high with sire-daughter matings but lower in other inbred matings than in 

 the checks. Outside stock from three different sources, when mated to Station 

 stock, gave no infertile matings, but stock from two other outside sources gave as 

 many infertile matings as did most inbred matings. 



IL There was no correlation between fertility of mothers and daughters, 

 suggesting that fertility does not depend on inheritance. 



References 



Crew, F. A. E. 1926. On fertility in the domestic fowl. Proc. Roy. Soc. Edinb. 



46 (20):230-238. 

 Curtis, v., and W. V. Lambert. 1929. A study of fertility in poultry. Poultry 



Sci. 8 (3):142-150. 

 Dunn, L. C. 1927. Selective fertilization in fowls. Poultry Sci. 16 (5):201-214. 

 Jull, M. A. 1935. Studies in fertilitv in the domestic fowl. Poultry Sci. 14(1): 



37-41. 

 Warren, D. C., and Lester Kilpatrick. 1929. Fertilization in the domestic fowl. 



Poultry Sci. 8 (5):237-256. 



Publication of this Document Approved by Commission on Administration and Finance 

 3500-5-'39. No. 7386. 



