Study of Prolactin gene associations with milk production traits in Iranian proved Holsteins

A total of 130 Iranian Holstein bulls were used to study polymorphisms of the prolactin (PRL) gene. The genotypes were detected by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). The frequencies of A and G alleles for PRL gene were 0.873 and 0.127, respectively. The, PRL-RsaI genotypes distributed according to the Hardy–Weinberg equilibrium (P 0.05). No significant correlation (P 0.05) was found between genotypes of the PRL-RsaI, with studied milk production traits. It may be necessary to carry out further studies with larger sample sizes to make a clear results between detected variants and milk production traits.