ANALYSIS OF SUBFERTILITY ASSOCIATED WITH HOMOZYGOSITY OF THE ROSE COMB ALLELE IN THE MALE DOMESTIC-FOWL

Sperm metabolism and duration of fertility were compared between roost ers homozygous (PR) and heterozygous (Rr) for the rose comb allele. In the absence or presence of Ca+2, a motility agonist, the metabolic ra te of spermatozoa from RR males was 76 to 77% of that of spermatozoa f rom Rr males. In the presence of caffeine, the metabolic rate of sperm atozoa from RR males was increased significantly (P < .05) to 86% of t hat of spermatozoa from Rr males. Although intramagnal insemination of ejaculated spermatozoa reduced the disparity in duration of fertility between RR and Rr males, the duration of fertility of PR males was st ill less than that of Rr males. No difference in duration of fertility was observed following intramagnal insemination of testicular spermat ozoa. Subfertility associated with RR males seems to stem from an aber rant activation or regulation of spermatozoal metabolism and not a red uction in absolute metabolic capacity per se.