Estimation of association between leptin gene polymorphism and somatic cell count and milk production traits in cattle

A total of 699 Holstein-Friesian (Red-White strain) cows were used to investigate how leptin gene polymorphisms affect somatic cell count (SCC) and milk production traits such as daily milk yield, fat content, protein content and dry matter content. Three single nucleotide polymorphisms (SNPs) were genotyped, including the Sau3AI and Sau' polymorphisms in intron 2 as well as the A59V polymorphism in exon 3. The genotype, allele and haplotype frequencies were estimated. Statistical analysis revealed that the Sau3AI and Sau' polymorphisms significantly affected the fat content and dry matter content (P <= 0.01, P <= 0.05) with C and 2 as desirable alleles respectively. No associations were observed between the A59V polymorphism and the traits analysed in this study. However, the genotype combinations (haplotypes) significantly affected the fat content and dry matter content. The results indicated that selection for the Sau3AI CC and Sau' 22 animals might contribute to increase fat content in Holstein-Friesian cattle.