Single nucleotide polymorphisms of the prolactin receptor (PRLR) gene and its association with growth traits in Chinese cattle.

Genetic polymorphism of the prolactin receptor (PRLR) gene was detected by PCR-SSCP and DNA sequencing methods in 665 individuals from five Chinese cattle breeds. The results showed that at the P1 locus, three observed genotypes (AA, AB and BB), two linked SNPs (G1267A and T1268C), and one missense mutation (S18N) within a putative signal peptide were determined. The frequencies of haplotypes A and B in the five breeds were 0.596-0.802 and 0.198-0.404, respectively. Polymorphism of the PRLR gene was shown to be significantly associated with growth traits in the Nanyang breed. Individuals with genotype BB had greater hucklebone width, body weight and average daily gain than those with genotype AA at 6 months old (P<0.01), as well as better body height, body length and heart girth when 6 months (P<0.05). This study revealed for the first time that the PRLR gene is a promising candidate gene that affects growth traits in cattle.