Pit-1 Gene Polymorphism of Holstein Cows in Isfahan Province

A total of 262 Holstein cows of four different herd managements in Isfahan province were used to obtained polymorphism of Pit-1 gene for a possible genetic marker information. Average frequency of the A allele among herds was 0.256 while the frequency of B allele was 0.744. Results showed there was no significant relationship between herd management and genotypic frequency, for different herds. However, BB genotype was the most frequent in the 1st, 2nd and 4th herds (0.500-0.600), while in the 3rd herd AB genotype was the most frequent one (0.564). AA genotype was the least frequent frequency (0.018-0.050) among all the genotypes. Statistical analysis showed that there was no Hardy-Weinberg equilibrium for average genotypic frequencies of different herds. Overall, the lack of equilibrium seems to be due to preference of AB genotype in the studied populations which could be as a result of selection that normally would apply in commercial herds. It should be noted that dairy producer in Iran, prefer dairy cattle for fast growing male calves and preference of fat milk daughters.