Investigation of the 5′ flanking region and exon 3 polymorphisms of IGF-1 gene showed moderate association with semen quality in Sanjabi breed rams

Abstract

In this study, semen samples were collected from 96 Sanjabi rams in order to investigate the IGF-1 gene polymorphisms and their relationship with the characteristics of semen quality and testicular size. The dimensions of scrotal length, width and circumference were measured during autumn and spring over two years. Blood samples were simultaneously collected from jugular vein to extract DNA. PCR was performed using specific primers to amplify 294 and 272bp fragments including 5′ regulatory region and exon 3 of IGF-1 gene, respectively. PCR products were digested by BFOI and Eco88l restriction enzymes, respectively. Two genotypes including AA (194 and 100bp), AB (294, 194 and 100bp) and all possible genotypes including CC (182 and 90bp), CT (272, 182, and 90bp) and TT (272bp) were observed for 5′ flanking region and exon 3 of IGF-1 gene, respectively. The significant differences among IGF-1 genotypes for testicular dimensions were not observed. However, the polymorphism of 5′ flanking region in the studied population had significant effect on individual motility and percent morphology traits. Animals with AB genotype had significantly higher individual motility compared with AA genotype (P < 0.05). Also, animals with AA genotype had significantly the highest percent morphology compared with AB genotype (P < 0.1). The exon 3 of IGF-1 gene had significant effect on individual motility, concentration, morphology and water test traits. Animals with CT genotype had the highest sperm concentration (P < 0.1) and water test (P < 0.05) compared to CC and TT genotypes. Moreover, animals with TT genotype had significantly the highest percent morphology compared with other genotypes (P < 0.05). Briefly, the results indicated that individual motility, concentration, percent morphology and water test traits could be in association with IGF-1 genotypes. It might be concluded that polymorphisms in IGF-1gene can be considered to develop male fertility in future and for using in selection process of better animals under masker assisted selection programs.