Semen Quality of Rasa Aragonesa Rams Carrying the Allele of the Gene.

The mutation is a variant of the ovine gene in the Rasa Aragonesa breed. Information on the physiological importance of carrying the polymorphism in rams is limited. The aim of this study was to compare semen quality, testicle characteristics, and fertility rate of rams that carry the allele. Rams ( = 15) were either FecXR allele carriers ( = 10) or non-carriers, wild type (++) ( = 5). FecXR rams exhibited higher mass motility ( < 0.05), proportion of rapid sperm ( < 0.05), and a lower proportion of slow sperm ( < 0.0001) than did ++ rams. The presence of the allele was not associated with mean scrotal circumference or testicular length and diameter, although season had a significant ( < 0.05) effect on these traits. Genotype ( < 0.05) and season ( < 0.01) had a significant effect on mean fertility rate, FecXR rams had a higher proportion of pregnant ewes than did ++ rams ( < 0.05). In conclusion, the allele produced high-quality semen throughout the year, and corresponded with an improvement in some sperm parameters, particularly, mass motility and the proportion of rapid sperm.