Studies of the Relationship Between Fertility and the Gene for Rose Comb in the Domestic Fowl

IN THE first report of this series (Crawford and Smyth, 1964), data from natural matings and from artificial inseminations were presented which indicated that the subnormal reproductive ability of White Wyandottes was due to the poor performance of homozygous rose comb (RR) males. Heterozygous males, and females of both rose comb genotypes, were found to reproduce normally. It was concluded, from microscopic examination of blastodiscs of unincubated eggs, that the problem was one of infertility. In the present report, comparisons of duration of fertility and of sperm transport among males and females of RR, Rr, and rr comb genotypes will be described. Stocks: The two populations of birds derived from the Ottawa Meat Control strain (O.M.C. strain) used in these studies and the additional stocks against which they were tested have been described earlier (Crawford and Smyth, 1964). During all of the experiments reported here, the males…