Characterization of polymorphism in the FSH receptor gene and its impact on some reproductive indices in dairy cows.

Follicle stimulating hormone (FSH) is released from the anterior pituitary gland and has an important role in female fertility. As FSH is a glycoprotein polypeptide hormone which cannot pass through the cell membrane, its influence on target cells must be mediated by the FSH receptor (FSHR). Accordingly, any kind of mutation in FSHR can affect reproduction in dairy cows. In this study, the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used for recognition of a point mutation (A/G: position -278) located in the FSHR gene in Iranian dairy cows. The association was evaluated of this mutation with reproductive performance. Blood samples were collected from 79 cows in a dairy farm in Iran and genotyped based on this single nucleotide polymorphism (SNP). The 5'-flanking regions of FSHR gene were successfully amplified and produced a fragment of 211bp in all cases. Three different patterns were, however, produced following restriction digestion with FaqI enzyme. The molecular results showed the existence of three different genotypes of AA, AG and GG among examined cows. In this study percentages of genotypes were 51.9%, 43.2% and 4.9% for AA, AG and GG genotypes, respectively. Allele frequencies were 73.5% and 26.5% for A and G, respectively. Results indicate that cows lacking allele G had desirable fertility in which a greater percentage (53.7%) of cows lacking Allele G (AA) had services per conception (SPC) of <2 in the previous lactation; while a lesser percentage of cows with Allele G (28.9%) had SPC of <2 (P<0.05). There was no difference in the days non-pregnant (DNP) and calving to first service interval among cows with these genotypes (P>0.05). Calving to first service interval was 69.9 ±12.3 in cows with Allele G and 74.73±13.9 in cows without Allele G (P>0.05). Percentage of cows with repeat breeder syndrome (SPC >3) was also 15.6% and 27.6% in cows without Allele G and with Allele G, respectively, but these values were not different (P>0.05). It can be concluded that the A to G mutation within the upstream region of FSHR gene (position -278) may affect some reproductive variables in Holstein dairy cows.