Evaluation of ACE, SP17, and FSHB as candidates for stallion fertility in Hanoverian warmblood horses

The research of fertility in humans and other mammals has strongly advanced in the recent years. The examination of molecular mechanisms influencing horse fertility is relatively recent. We chose the angiotensin converting enzyme (ACE), the sperm autoantigenic protein 17 (SP17) and the follicle stimulating hormone (FSHB) as candidates for determining stallion fertility and to analyze associations of intragenic single nucleotide polymorphisms (SNPs), flanking microsatellites and candidate-gene linked haplotypes with the pregnancy rate per oestrus (PRO) in 179 Hanoverian stallions. Fertility traits analyzed were the least square means of PRO for stallions (LSMs) and the paternal and embryonic component of breeding values for PRO (BVs). We detected nine SNPs and two flanking microsatellites in ACE, eight SNPs and two flanking microsatellites in SP17 and four SNPs and one flanking microsatellite in FSHB. Three SP17-associated SNPs and the two flanking microsatellites showed significant association with the embryonic component of BVs and one SP17-associated microsatellite was also significantly associated with the paternal component of BVs. Two ACE-associated SNPs were significantly associated with the embryonic component of BVs. Significantly associated haplotypes were shown for all three candidate genes and the tested fertility parameters. The final regression analysis model indicated that haplotypes of all three candidate genes significantly contributed to the paternal and embryonic fertility components of PRO. This is the first report of associations of ACE, SP17 and FSHB with fertility traits of stallions.