Association of IL8 -105G/A with mastitis somatic cell score in Chinese Holstein dairy cows.

The single nucleotide polymorphisms (SNPs) in the 5' upstream of bovine IL8 gene were investigated in 810 Chinese Holstein cows from 35 bull families in a dairy farm in Shanghai using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique. The Real-time PCR and Western blot were used to detect the mRNA and protein levels of genotype Chinese Holstein dairy cows. The results showed that one SNP -105G>A was detected, designating three genotypes (GG, GA and AA) with respective frequencies of 0.38, 0.46, and 0.16. The significant association of the SNP -105G>A with somatic cell score (SCS) was identified. Genotype GG had a significantly lower SCS than genotype GA or AA (P < 0.01), and the relative mRNA expression and protein level of GG was found to be the highest. These results suggest that the genotype GG may be a useful genetic marker for mastitis resistance selection and breeding in Chinese Holstein dairy cows.