Abstract:

【Objective】 The polymorphism of CXCR1 gene and their correlation with somatic cell score(SCS) in Chinese Holstein cattle was analyzed for the purpose of providing molecular markers in the marker-assisted selections (MAS) to accelerate the disease-resistant breeding progress in Chinese Holstein cattle. 【Method】 The polymorphism of CXCR1 gene was detected by polymerase chain reaction-single strand comformation polymorphism (PCR-SSCP) technique in 610 Chinese Holstein cattle from 30 bull families.The association between polymorphic sites of CXCR1 gene and SCS was analyzed by the least square mean analysis, and the PHASE software was used as haplotype analysis 【Result】 Four SNPs were found, three SNPs (-1830(A/G), -1768(T/A), -344(T/C))were found in 5ˊflanking region, SNP 783(C/A) was reported in the coding region for the first time. At -1830(A/G) site, AA genotype had greatly significantly lower SCS than AG genotype (P＜0.01), at -1768(T/A) site, TT genotype had greatly significantly lower SCS than TA genotype (P＜0.01), at -340(T/C) site, TT genotype had greatly significantly lower SCS than TC and CC genotypes (P＜0.01). There were no significant differences in SCS among two genotypes at 783(C/A) site. The SCS of Haplo2(ATTA) haplotype homozygous genotype was significantly lower than that of Haplo1(ATCA), Haplo3(GACA) and Haplo4(GATA) haplotype homozygous genotypes (P＜0.01). 【Conclusion】 AA genotype at -1830(A/G) site, TT genotype at -1768(T/A) site, TT genotype at -344(T/C) site and Haplo2(ATTA) haplotype homozygous individuals had a great genetic effect on SCS in Chinese Holstein cattle, which can be used as candidate markers for mastitis resistance selection in dairy cattle.

Key words: Chinese Holstein cattle, CXCR1 gene, PCR-SSCP, polymorphism, haplotype, SCS