Leptin gene polymorphism in Romanian cattle breeds and associations with milk production traits

The leptin (LEP) gene, mapped on chromosome 4q32 in cattle, is considered a potential QTL, influencing different traits, including those related to milk. Various single nucleotide polymorphisms (SNPs) were reported, several of them being associated with milk, fat, and protein yields or fat and protein percentages. One of them, A1620G, was chosen as the aim of our investigation, two alleles (A and G) and three genotypes (AA, AG, GG) being identified in a population of 82 Romanian Spotted and 55 Romanian Brown cattle. The G allele was predominant in both breeds (62.20% in Romanian Spotted and 73.64% in Romanian Brown), the AG genotype in Romanian Spotted (68.29%), whereas both AG and GG in Romanian Brown cattle (each of them, 49.09%). For 23 Romanian Spotted and 29 Romanian Brown cows, associations of LEP A1620G genotypes with milk, fat, and protein yields, fat and protein percentages were investigated. No significant differences were found among genotypes, but differences were found among breeds. This might be due to the influence of a small number of the individuals included in this second part of research and is the reason why we consider an enlargement of the base study for further studies, including here individuals'number and LEP loci number.