Evaluation of prolactin receptor (PRLR) as candidate gene for male fertility in Hanoverian warmblood horses.

Stallion fertility has increasing importance as the artificial insemination is employed in horses more intensely. Molecular genetic markers may be useful tools to evaluate the stallion fertility before breeding. The prolactin receptor gene (PRLR) was chosen as a candidate for stallion fertility because of its influence on testicular and accessory sex gland function. Screening the equine PRLR gene for polymorphisms in Hanoverian stallions revealed two single nucleotide polymorphisms (SNPs). Association and haplotype analyses were performed in 162 Hanoverian warmblood stallions for these intragenic SNPs using the least square means (LSM) of the pregnancy rate per oestrus for stallions and the paternal component and embryonic component of the breeding values (BV) of the pregnancy rate per oestrus. The two SNPs (BIEC2-589441, BIEC2-560860) showed significant associations using single marker and haplotype analysis with the embryonic and paternal component of BV and one SNP (BIEC2-560860) was also significantly associated with the LSM of the pregnancy rate per oestrus. This is the first report on an association of PRLR-associated genetic markers with fertility traits in stallions.