Association of bovine PPARGC1A and OPN genes with milk production and composition in Holstein cattle

Several studies have reported quantitative trait loci on chromosome 6 affecting milk production and composition traits in dairy cattle. Osteopontin (OPN) and peroxisome proliferator activated receptor-γ coactivator-1α (PPARGC1A) genes have been located on this chromosome and identified as positional candidates for milk traits. We investigated the associations of single nucleotide polymorphism (SNP) T>C at position 1892 and SNP A>C at position 3359 in PPARGC1A gene as well as SNP C>T at position 8514 in OPN gene with milk production and composition. Hence, 398 Iranian Holstein cows were genotyped through polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). The Least Squares methods were used to examine the effects of genotypes on milk traits. The frequencies of the C allele at position 1892, A allele at position 3359, and T allele at position 8514 were 0.56, 0.64, and 0.53, respectively. In this study, c.1892T>C genotypes indicated significant associations with milk fat content adjusted for two milkings per day (FATP2X; %), estimated breeding value for milk (EBVM; kg), milk protein yield adjusted for mature body weight (PROME; kg), milk protein yield adjusted for 305 days (PRO305; kg) (P < 0.05), and estimated breeding value for milk fat content (EBVFP; %) (P < 0.01). There were significant associations between c.3359A>C genotypes and FATP2X, EBVFP (P < 0.01). Moreover, significant associations were shown between c.8514C>T genotypes in OPN gene and FATP2X (P < 0.05), and PROPER305 (P < 0.01). Thus, these SNPs would provide an excellent opportunity for marker assisted selection programs in dairy cattle.