Analysis of association among four candidate genes polymorphisms with milk yield and reproductive performance traits in Sarabi cow using PCR-RFLP marker

Selection for improving of production and reproductive performance traits in livestock is a time-consuming process and can only be applied to adult animals. Sarabi cow is one of the local Iranian dairy breeds with dominate geographical distribution on NorthWest of Iran. Characterization of candidate genes associated with milk yield and reproductive performance traits is important and can help to improve the efficiency of breeding programs in this breed. Therefore, the objective of the present study was to evaluate the association among four candidate genes (Leptin, Growth Hormone (GH), Growth Hormone Receptor (GHR) and pit-1) with milk yield and some reproductive performance traits in Sarabi cattle breed using PCR-RFLP marker. The obtained results revealed that the highest allele frequencies were observed for A (0.72), V (0.51), + (0.65) and B (0.55) for Leptin, GH, GHR and pit-1 genes respectively. The respective LL, -/- and AB-BB genotypes of GH, GHR and pit-1 genes showed higher milk yield production compare to other genotypes of these genes <em>(P< 0.01).</em> Also,<em> </em>LL and AB genotypes of GH and pit-1 genes were related to shorter open days <em>(P< 0.01). </em>No evidence showing the association between other genotypes of these genes and the other investigated traits were observed in the present study. Overall, candidate genes showed deficiency of observed heterozygosity value compare to the expected heterozygosity value. In addition, the results of chi-square analysis showed that all candidate genes were in Hardy-Weinberg disequilibrium. As a conclusion, the finding of the present study revealed the association of investigated candidate genes with milk yield and open days in Sarabi cattle breed and the application of these polymorphisms for marker assisted selection (MAS) should be further evaluated.