Short communication: Differential endocrine and antioxidant responses to heat stress among native and crossbred cattle

Abstract

The present study was undertaken to evaluate the comparative effect of in vivo heat stress on native and crossbred cattle based on specific hormone responses and antioxidant enzyme activities. Eighteen healthy cattle aged between 4 and 5 years were selected and divided into three equal groups (n = 6) with consideration of breed as Sahiwal, Tharparkar, and crossbred (Hariana × Holstein Friesian/Brown Swiss/Jersey). The temperature-humidity index was calculated using temperature and relative humidity daily throughout the experimental period. Blood sampling was performed during summer and winter and the serum was used for the estimation of hormones such as triiodothyronine, thyroxine, and cortisol. The enzymatic antioxidant activity of catalase, superoxide dismutase, glutathione peroxidase, and total antioxidant capacity was also recorded. Temperature-humidity index values indicated that the animals were under thermal stress in summer but thermoneutral in winter. During heat stress, significant higher levels of triiodothyronine and thyroxine were observed in native cattle compared with the crossbred cattle. A significantly higher (P < 0.05) concentration of serum cortisol was recorded in crossbred cattle when compared with native breeds in summer. The total antioxidant activity (TAC) during summer was observed significantly (P < 0.05) high in Tharparkar cattle followed by Sahiwal and then crossbred. There was no significant difference in superoxide dismutase, catalase, and glutathione peroxidase activities between breeds in both the seasons. It can be concluded that indigenous cattle Tharparkar, followed by Sahiwal, exhibited more tolerance to heat stress than the crossbred during summer.