Abstract: In order to clarify interleukin 8 （IL8） gene in the genetic variability of different domestic cattle populations， we detected IL8 gene 3′ untranslated region mutations among Chinese Holstein， Wenling humped cattle and Wenzhou buffalo by application of PCR\|SSCP technique. One haplotype block， containing g. 2831A/G， g. 2904 T/C， and g.3030 G/A was identified in 3′ UTR of IL8 gene by PCR\|SSCP and DNA sequencing in Chinese Holstein and Wenling humped cattle， while Wenzhou buffalo individuals were homozygous for the “mutant allele” in the same loci. The effect of IL8 gene 3′ UTR polymorphisms on Chinese Holstein 305\|day corrected milk yield fat percentage， protein percentage and somatic cell score was assessed by general liner mode. Three mutations in IL8 gene 3′ UTR were significantly associated with Chinese Holstein 305\|day corrected milk yield （P<001） and fat percentage （P<005）.

Key words: IL8, 3&prime, UTR, SNPs, Chinese Holstein, Wenling humped cattle, Wenzhou buffalo