Hadi Rahmati - Department of Animal Science, Mashhad Branch, Islamic Azad University, Mashhad, Iran
Mojtaba Hosseinpour Mashhadi - Department of Animal Science, Mashhad Branch, Islamic Azad University, Mashhad, Iran
Mahdi Elahi Torshizi - Department of Animal Science, Mashhad Branch, Islamic Azad University, Mashhad, Iran

The aim of this study was to investigate the polymorphism of leptin gene and its effects on milk production traits in Holstein cattle.In order to investigate the relationship between the polymorphism of leptin gene and some milk production traits in Holstein cows, blood samples were collected from 100 cows from a dairy farm in Khorasan Razavi province. GeNet Bio was used to extract the DNA from the commercial kit. In order to amplify a fragment of 94 pairs of the gene, the Pfu PCR PreMix (AccuPower-South Korea) was used to amplify the gene. Polymerase chain reaction (PCR) was performed for amplification of 94 pairs of games using a pair of proprietary initiators. The fragment was digested by PCR-RFLP by KPN2I restriction enzyme. Statistical data was analyzed using POPGENE software version 1.32 . The genotype of each animal was determined by using RFLP method and 3% agarose gel and ethiodium bromide staining. For digestion of PCR products, 1 unit KPN2I enzyme was used at 37 ° C for 6 hours. The frequency of T and C alleles were 0.53 and 0.47, respectively, and the TT and CT and CC genotypes were 0.397, 0.266 and 0.337, respectively. Chi square test showed that the studied population was not in Hardy Weinberg equilibrium (p <0.05). The relationship between the polymorphisms and traits was evaluated by SAS software. The Duncan test was used to compare the average of milk production traits. The polymorphism of the leptin gene was not significantly correlated with the traits of the milk yield, fat content, and milk protein content and percentage (P> 0.05). There was a significant relationship between the leptin polymorphism and the level of S.C.C (P <0.05) the highest mean of somatic cell count was related to TT genotype. This suggests the possible role of the leptin gene in the regulation of immune responses and the occurrence of mastitis.

Polymorphism, Leptin Gene, Holstein Cow, PCR-RFLP