Identification of g.170G>A and g.332G>A mutations in exon 3 of leptin gene (Bcnl and Cail) and their association with semen quality and testicular dimensions in Sanjabi rams.

The purpose of this study was to investigate leptin gene polymorphisms and their relationships with the characteristics of sperm quality and testicular dimensions. Semen samples were collected from 96 Sanjabi rams during autumn and spring seasons over two years. Simultaneously, the dimensions of length, width and scrotal circumference were measured. Blood samples were taken from the jugular vein to extract DNA. PCR was performed to amplify a 463bp fragment including exon 3 of leptin gene. PCR products were digested by Bcnl and Cail restriction enzymes to identify 170G>A and 332G>A mutations in exon 3, respectively. Leptin gene polymorphism in 170G>A locus had an effect on individual motility trait, water test and scrotal circumference (P<0.05) and animals with the AA genotype had the highest individual motility compared with the GG and GA genotypes (P<0.05). The AG genotypes had the highest water test compared with the GG and AA genotypes (P<0.05) but GG genotype had higher scrotal circumference than that of GA and AA genotypes (P<0.05). The results showed that polymorphism in 332G>A locus had a significant effect on viability trait, water test and scrotal circumference as GA genotypes had the highest amounts for these traits compared with GG genotypes (P<0.05). Based on our knowledge, the current study is the first report on the association of leptin gene polymorphisms with sperm fertility and testicular dimensions in sheep, which suggests leptin gene as a potential gene to be used in breeding programs in order to improve fertility in herds.