Association Of Microsatellite Markers With Physiological-Biochemical Indexes And Milk Yeild Of Diary Cows In High Temperature

The study aimed to reveal relationship between3microsatellites polymorphism of GSH-Px, SOD, Na+/K+-ATPase and daily milk yield by investigating physiological changes(respiratory rate and rectal temperature), antioxidant index (GSH-Px, SOD, and MDA), Na+/K+-ATPase activity and content of erythrocyte potassium of160Holstein cows in different seasons with variant humidity. The results showed that:1Influence of high temperature on physiological and biochemical parameters of Holstein cowsThe influence of temperature on rectal temperature, respiratory rate, GSH-Px activty, SOD activity and content of MDA of dairy cows were analyzed. The value of temperature-humidity index (THI) of the dairy sheds was all above72in summer. Compared to the group in fall, rectal temperature and respiratory rate of the in summer were significantly higher (P<0.01), and the GSH-Px and SOD activity were significantly lower (P<0.01), meanwhile, the content of MDA was significantly higher (P<0.05).2Relationship between Na+/K+-ATPase activity and productivty of Holstein cowsNa+/K+-ATPase activity, potassium content in erythrocyte and milk yield were determined in summer and fall. The Na+/K+-ATPase activity, potassium content in erythrocyte and milk yield were significantly higher in summer when the cows were suffering from heat stress(P<0.05). The cows with increased Na+/K+-ATPase activity showed a significantly rise of milk yield. Results implied significantly negative correlation (r=-0.784, P<0.01) between red cell potassium and drop rate of milk yield, and positive correlation (r=0.464, P<0.05) between Na+/K+-ATPase activity and red cell potassium.3Relationships of3Microsatellite loci with Enzyme Activity and Daily Milk Yields in Different Seasons in Holstein CowsGenetic variation of three microsatellite loci BMS2258, SOD1and BM723which were closely correlated with GSH-Px, SOD and Na+/K+-ATPase gene were analyzed in160Holstein cows by nondenaturing polyacrylamide gel-electrophoresis, respectively. Allele frequency, heterozygosity, polymorphic information content, and effective number of alleles of the three microsatellite loci were calculated. Relationships of three microsatellite loci with enzyme activity and daily milk yields in Holstein cows were preliminarily analyzed by least squares linear model. The results indicated significant correlations of microsatellite BMS2258with GSH-Px acticity and daily milk yield, microsatellite SOD1with SOD activity and daily milk yield, as well as microsatellite BM723with Na+/K+-ATPase activity and daily milk yields in summer and fall.182bp/164bp at BMS2258,148bp/148bp at SOD1, and161bp/lllbp at BM723were the most favourable genotypes for daily milk yield.182bp/164bp at BMS2258,148bp/146bp at SOD1, and161bp/lllbp at BM723was the most favourable genotype for GSH-Px acticity, SOD activity and Na+/K+-ATPase activity in summer and fall, respectively.It was concluded that:(1)Heat stress imposed significant influence in the rectal temperature and respiratory rate of cows.(2)High temperature had significant influence on the antioxidant index, Na+/K+-ATPase activity and red cell potassium of cows.(3)Microsatellite BMS2258, SOD1and BM723significantly correlated with GSH-Px, SOD, Na+/K+-ATPase acticities and daily milk yield in summer and fall.