The follicle-stimulating hormone (FSH) acts on the sertoli cells in the seminiferous tubules of the testis and regulates spermatogenesis up to the secondary spermatocyte stage. Allelic and genotypic frequencies of bovine follicular stimulating hormone (exon III) gene were studied for 83 animals from Iranian Holstein bulls. The blood and semen samples were collected from two artificial insemination and progeny test center (Jahed Co, Karaj, Iran and Shikh Hassan, Tabriz, Iran). We used polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) for animal genotyping. The PCR process conducted with protocol of Dai et al. (2009). PCR products were digested with 4 U of PST-I, using the supplied buffer and maintained at 37°C for1 h. The resulting fragments were separated by vertical electrophoresis (110 W 40 min) in3% agarose gel, stained with ethidium bromide and was visualized under UV light. The A (PST-I) allele had fragment sizes of 111, 202bp, whereas the B (PST-I) allele had fragments of 111, 202 and 313bp. The frequency of the A (PST-I+) and B (PST-I-) alleles are 0.675 and 0.325 respectively. The genotype frequency for AA and AB were 0.35 and 0.65 respectively. The BB genotype was omitted of analysis.
