Single nucleotide polymorphism detection of the HSP70-A8 gene by PCR-SSCP and analysis of its relationships with DHI performance measures in Holstein cattle
319 Holstein cattle were used to detect the polymorphism of the HSP70-A8 gene using PCR-SSCP method. The results showed that a GC mutation occurred in 1522 base position in exon 1 of HSP70-A8, and three genotypes(AA,AB and BB) were found, in which genotypic frequency of AA was 38.56%, AB was 31.03% and BB was 30.41%. The polymorphism information content(PIC) was 0.3733 in the population, showing a moderate polymorphism. According to the results of χ2 test, the locus was in Hardy-Weinberg non-equilibrium state in the population. No pdymorphism was detected in exon 2 to 8 of the HSP70-A8 gene in the population. It was investigated that cows with BB genotype had higher lactation to date milk yield, lactation to date fat-corrected milk yield, 305-day fat-corrected milk yield, 305-day fat yield, 305-day protein yield, lactation to date fate yield and lactation to date protein yield than cows with AA and AB genotypes(P0.01). Cows with AA genotype had lower somatic cell numbers than cows with AB and BB genotypes(P0.01). It was suggested that exon 1 of HSP70-A8 should be selected as one of indicator molecular marker genes for milk performance of Holstein cattle.