GnRHR gene polymorphism and its correlation with semen quality in Buffalo bulls (Bubalus bubalis)

Fresh semen from fifty bulls was evaluated for ejaculate volume, individual motility, concentration, lives sperm and abnormalities as well as acrosome integrity. Bulls were classified according to semen motility into two groups; good and poor. DNA was extracted from semen of both groups, then the PCR followed by single-strand conformation polymorphism (SSCP) techniques were performed for mutation detection in gonadotropin releasing hormone receptor (GnRHR) gene through multiple sequence alignment. The results showed that the percentages of sperm motility, sperm concentration and live sperm, were significantly higher in good than poor semen quality bulls. However, semen volume, percentage of acrosome integrity and abnormalities did not differ between good and poor. The PCR amplification of 240-bp fragment and the results of SSCP appeared a genetic polymorphism with two patterns. Pattern I was seen in all good bulls, with incidence of 100%. Pattern II appeared only in poor semen quality bulls with a frequency of 31.25%. The sequence analysis of the PCR product for the two patterns showed two single nucleotide polymorphisms (SNPs) as a transversion base substitution mutation at positions 20 (T/A) and 193 (A/T). The GnRHR gene could be used as a genetic marker related to semen quality in buffalo due to the good semen bulls had a unique pattern.