Association between Genotypes of Growth Hormone Gene and Semen Quality Traits in Cow Bulls and Buffalo Bulls

The aim of this study was to detect the genetic polymorphism within the growth hormone gene Alu 1 locus in both Egyptian river buffalo and Holstein bulls using PCR-RFLP technique. The study was conducted on a total of 64 bulls which included 34 Egyptian buffalo bulls and 30 Holstein bulls. All the investigated buffalo bulls were genotyped as LL genotype. In turn, 25 and 5 Holstein bulls were of LL and LV genotypes, respectively while none of the examined cow bulls was genotyped as VV genotype. The genotype frequencies of LL and LV genotypes in Holstein bulls were 83.3% and 16.7%, respectively while the allelic frequencies of L and V alleles were 0.92 and 0.08, respectively. The obtained results revealed a significant positive association (P 0.05) between the LV genotype and semen volume, percentage of individual motility and post-thawing motility in the examined cow bulls while no sign of association with other investigated semen quality traits was observed. In conclusion, the buffalo growth hormone gene was found to be monomorphic for this locus while polymorphism in growth hormone can be a candidate gene for selection of Holstein bulls used in artificial insemination centers where we can early predict their fertility after the birth.