The chemokine receptor 1 gene polymorphism and its association with Somatic Cell Score and milk production traits in dairy cattle*

CXC chemokine receptors 1 (CXCR1) play a key role in inflammatory response and eventual activation of the innate immunity. Mastitis is a big problem in dairy industry. In the presented study the bovine CXCR1 gene was considered a candidate gene of anti-mastitis defense in Chinese Holsteins. Polymorphism of bovine CXCR1 was investigated and its associations with Somatic Cell Scores (SCS) and milk production traits (milk yield, milk fat and milk protein content) analysed. Six single nucleotide polymorphisms (SNP) were identified within a 311 bp segment of the bovine CXCR1 locus at positions +570 (G>A), +642 (G>A), +735 (G>C), +816 (C>A), +819 (A>G) and +820 (G>A) relative to the available mRNA sequence, of which CXCR1c.+820 G>A was revealed for the first time. The SNP CXCR1c.+735G>C resulted in the mutation of amino acid, but it showed no significant association with the SCS, milk yield, milk fat and milk protein percentage of Chinese Holsteins (P>0.05). Fifteen haplotypes were reconstructed by the six SNPs in the sample of Chinese Holstein population. The most common haplotype was Haplo1 carrying alleles AAGCAG equal to 0.37, followed by 7 haplotypes (from 2 to 7) with frequencies equal to 0.13, 0.11, 0.08, 0.08, 0.07, 0.07 and 0.06, respectively. Haplotype analysis revealed no significant associations with SCS and other milk production traits.