Abstract：Abstract: iSingle strand conformation polymorphism (PCR-SSCP) and direct sequencing methods were used to analyze the polymorphism at 3′-UTR of HSP70 gene in bovine.The PCR-SSCP products showed that there was polymorphism and could be divided into three genotypes: AA, AB, BB among 673 Luxi and Holstein cattle. The direct sequencing of products showed that there was a new SNP in the 3′-UTR of the hsp70 gene.In this study the cows with BB genotype showed higher milk fat percentage, milk proteinum percentage and 305 days milk yeld than that of AA genotype,and cows with BB genotype showed lower blood potassium and milk production decrease ratio (p<0.05). Cows with BB genotype have higher heat tolera nce than AB and AA. Luxi cattle have higher heat tolerance than Holstein. B allele frequency in Luxi cattle is much higher than that in Holstein which also suggest BB genotype have higher heat tolerance than AB and AA.This mutation site can be used as molecular genetic markers to assist the selection for anti-heat stress cows.
