Leptin plays a role in the regulation of appetite, energy partition, feed intake and body composition of mammals. The leptin gene influences economic traits in cattle such as meat production, milk performance, reproduction traits, and carcass quality. The objective of this study was to investigate the genetic variations in the exon2 region of the leptin gene for the Sarabi cattle breed of Iran. The measured traits included milk yield, fat yield, fat percentage, protein yield, and protein percentage. Blood samples were randomly collected from 274 Sarabi cows for genotyping of the leptin gene. The C and the T allelic frequencies were 0.67 and 0.33, respectively. Three genotypes (CC, CT and TT) were detected in the population with frequencies of 0.394, 0.555 and 0.051, respectively. The Average Heterozygosity was 0.436 in the population. The chi-square test confirmed Hardy-Weinberg equilibrium in the population. A univariate linear model was used to evaluate the association of each genotype with the traits. The CC and TT genotypes had significant effects on milk and protein yield (P<0.05). Cows with the TT genotype gave higher performance for milk yield, fat yield and protein yield. The association analysis showed a significant effect of the leptin SNP on protein and milk yield (p<0.05).

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