Effect of antioxidants supplementation on plasma hormonal profiles in Hallikar cattle during different seasons

Present study was carried out to ascertain the influence of different seasons on hormonal profiles in Hallikar cattle. Two groups (control and supplemented) of healthy female Hallikar cattle with six animals in each group selected from Madabal Village of Ramanagara District, Karnataka, India, were utilized for the present study. Selected animals were exposed to environmental stressors during three different seasons (winter, summer and rainy) by allowing them for grazing daily. Animals of control group received no supplementation but supplemented group received oral supplementation of vitamin E and selenium, during the study period. Blood samples collected from all the animals at monthly interval during three different seasons were processed to obtain the plasma which were stored at -80 degrees C until they are utilized for determination of hormones like triiodothyronine (T-3), thyroxine (T-4), insulin and cortisol using radioimmunoassay technique. In the present study, triiodothyronine and thyroxine levels reduced significantly (P<0.05) during summer season compared to other seasons in control group animals. In both control and supplemented group, plasma insulin levels declined significantly (P<0.05) and plasma cortisol levels increased significantly (P<0.05) during summer compared to other seasons. Form the study, it was concluded that the summer stress reduces the thyroid and pancreatic activity leading reduced secretion of thyroid hormones and insulin. Further, the summer stress stimulates the adrenal cortical activity leading to enhanced secretion of the cortisol in Hallikar cattle.