Rose comb and fertility in silver Spangled Hamburgs

EXTENSIVE studies have been conducted on the effects of the autosomal dominant gene for rose comb (R) on reproductive ability in domestic fowl. Crawford and Smyth (1964a) have shown that reproduction is faulty only in RR males, heterozygotes and homozygous recessive single-combed (rr) males being normal; females of all three genotypes reproduce equally well. The defect in RR males is expressed mainly as a reduction in fertility and in duration of fertility (Crawford and Smyth, 1964a, b). Petitjean and Cochez (1966) found that motility of sperm from RR males was decreased following in vitro storage. Reduced fumarase activity in sperm from RR males was subsequently demonstrated by Buckland et al. (1969), which may account for the observed low fertility. Nearly all of the reported studies have utilized the rose comb gene as obtained directly or indirectly from the Wyandotte breed. It has been of interest to consider whether the gene…