Impact of thermal stress and vitamine supplementation on heat shock protein -72 and antioxidant enzymes in murrah buffaloes.

Thermal stress, the “silent stressor” has unique and complex effect on livestock in altering the normal physiological mechanisms. Induction of HSP72 and antioxidant enzymes can be used as an index of stress levels. The stress can be lowered with the supplementation of vitamin E. Keeping these points in mind, the present study was planned to examine the relationship of HSP72 mRNA expression in lymphocytes with antioxidant enzymes (Superoxide dismutase and catalase), blood profile (TEC, TLC, DLC and N:L ratio), physiological responses (RR,PR, Tre , Tskin and heat storage) and the effect of vitamin E supplementation (summer and winter season) in different physiological stages of Murrah buffaloes. The study was divided into two experiments. Experiment I was carried out on six each of growing calves, heifers and lactating Murrah buffaloes by exposing the experimental animals at 38± 1° C with 50± 2%RH (ExposureI) and at 42 ± 1° C with 40 ± 2 %RH (ExposureII) in climatic chamber. The HSP72 mRNA expression in lymphocytes and erythrocytic antioxidant enzymes (SOD and CAT) activity increased significantly (P<0.05) in all the stages Murrah buffaloes during both the exposures. The magnitude of increase in both HSP72 mRNA expression in lymphocytes and antioxidants (SOD and CAT) was higher at exposureII. In experiment II, twelve each of growing, heifer and lactating buffaloes were selected and further divided into two groups (6 each) i.e., control and experimental animals. The experimental animals of growing calves, heifers and lactating buffaloes were fed vitamin E @ 500,800 and 1000 IU/animal/day respectively for a period of 30 days during summer and winter season. The control group of animals were maintained on normal feeding and managemental conditions. The results of the present study showed that in all stages of Murrah buffaloes, the HSP72 mRNA expression and antioxidant enzymes (SOD and CAT) significantly (P<0.05) decreased in experimental group of buffaloes compared to control group during both the seasons. Overall values of αtocopherol was significantly (P<0.01) higher in experimental groups as compared to control group. Milk yield in treatment lactating group was significantly higher (P<0.01) than control lactating group of buffaloes during summer and winter season. Based on the results of the present study, it can be concluded that thermal stress (climatic chamber and stress seasons) had a significant negative impact on buffalo physiology by increasing the levels of HSP72 mRNA expression in lymphocytes, antioxidant enzymes (SOD and CAT), N:L ratio, deviating the normal picture of TEC,TLC, and DLC and physiological responses (RR,PR, Tre , Tskin and heat storage). The feeding of vitamin E to the treatment group of buffaloes showed a positive impact by lowering the levels of thermal markers viz., HSP72 mRNA expression in lymphocytes, antioxidant enzymes (SOD and CAT), N:L ratio, increased the count of TEC and TLC, reduced the number of neutrophils, increased the number of lymphocytes, monocytes and eosinophils, improving the levels of αtocopherol in blood plasma of all categories of Murrah buffaloes and even increasing the levels of milk yield in lactating group during summer and winter season.