Evidence for effects of testis and epididymis expressed genes on sperm quality and boar fertility traits.

Retinol-binding protein 4 (RBP4), androgen receptor (AR), relaxin (RLN), acrosin (ACR) and osteopontin (polymorphism in intron 6 named OPNin6; polymorphism in promoter region named OPNprom) were addressed as functional candidate genes for sperm quality and boar fertility and investigated for their association with sperm concentration, motility, semen volume per ejaculate, plasma droplets rate, abnormal spermatozoa rate as well as non-return rate and number of piglets born alive. Therefore 356 AI boars of the purebred Pietrain (PI) and crossbred Pietrain x Hampshire (PI x HA) were genotyped at these loci. Analysis of variance revealed significant associations of RBP4 (p < 0.05), ACR (p < 0.01), and OPNin6 (p < 0.05) with sperm motility. OPNin6 (p < 0.05) was also associated with number of piglets born alive. Moreover, AR (p < 0.05) and OPNprom (p < 0.05) were significantly associated with abnormal spermatozoa rate. For RLN (p < 0.01) there was evidence for effects on sperm volume and ACR significantly affected sperm concentration (p < 0.05) as well as non-return rate (p < 0.05). No significant effects of any locus on plasma droplets rate were observed.