Single Nucldeotide Polymorphism Of Hsp70-1and Hsp32Gene And Their Correlations With Production Traits And Mastitis Resistance In Chinese Holstein Dairy Cows

Bovine mastitis, a major disease affecting dairy cattle worldwide, results from the inflammation of the mammary gland. Currently, milk quality payments are based on somatic cell counts (SCCs). This, in addition to reduction in milk volume and treatment costs, significantly affects farm incomes.Heat shock proteins (HSPs) are molecular chaperones essential for maintaining cellular functions by preventing misfolding and aggregation of nascent polypeptides and by facilitating protein folding. Heat shock protein synthesis is increased to protect mammalian hosts from various insults caused by infection, inflammation, or similar events. Both Hsp70-1and Hsp32can participate in immune reaction directly and indirectly, so they are very important for mammalian hosts to resist stress and different kinds of adverse environmental factors.DNA sequencing, Nest-PCR and PCR-RFLP were used to investigate mutations in the coding region of Hsp70-l and Hsp32gene in375Chinese Holstein dairy cows, and the associations between the polymorphisms and production traits and mastitis resistance were analyzed.â… . Genetic Polymorphism and Population Genetic Characteristics of Hsp70-1and Hsp32Gene in HolsteinThe Gâ†'A mutation at3099bp in Hsp70-1gene and Gâ†'A mutation at6356bp in Hsp32gene were found and both of them were silence mutations that caused no alteration in amino acid sequence. Chi-square test showed both loci were not in Hardy-Weinberg equilibrium in Chinese Holstein.â…¡. Genetic Polymorphism of Hsp70-1and Hsp32Gene and their Correlation with production traits and mastitis resistance.The associations between the polymorphisms and all production traits, except SCS, were not significant. The polymorphism in Hsp32gene affected SCS significantly (P=0.041), however, the association between the Hsp70-1polymorphism and SCS was not significant (P=0.053). After analyzing the relation between SCS and combined genotypes, the result showed that the combination of Hsp70-1genotype GG and the Hsp32genotype AA was the best one, the SCS of this combination was lower than almost all other combinations significantly or very significantly, so this combination may be used as a molecular and genetic marker to improve the phenotype of anti-mastitis in Chinese Holstein dairy cows.