Efficacy of turmeric (Curcuma longa) as antioxidant in combating heat stress in broiler chicken

Abstract

A study was undertaken to evaluate the antioxidants potential of herbal turmeric (Curcuma longa) in combating heat stress on120 broiler chicks in hot summer months. The day old Vencobchicks were randomly divided into five groups in a completely randomized design. The dietary treatments were basal diet (no antioxidant supplementation, BD), and the other four diets were BD supplemented with vitamin E (200 mg/kg), vitamin E (200 mg/kg) + Se (0.15 mg/kg), Turmeric (0.2%) and turmeric (0.4%), respectively. Additionally, a group of 24 chicks was raised separately in stress free environment on BD without any antioxidant supplementation and this diet acted as control. Blood was collected at 4th and 6th week of age from 12 birds from each group. Enzymatic and non-enzymatic antioxidant concentrations were estimated in plasma and cortisol concentration was analyzed in serum. Birds were vaccinated with Newcastle disease (ND) vaccine on 7th and 21st day and humoral response (HI) was assessed in sera samples at 4th and 6th wk of age. Cell mediated immune response (CMI) was assessed by injecting Phytohaemagglutinin (PHA-P) intra dermally into inter digital fold at the end of 4th and 6th wk and increase in the skin thickness was measured after 24 h. At the end of 42nd day, 6 birds from each group were sacrificed to observe the histological changes in bursa, spleen and liver. Serum cortisol was highest in heat stressed birds and lowest in heat stress free (control) group. On contrary, the activities of enzymatic antioxidants i.e. superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase and non enzymatic antioxidants (reduced glutathione) and immunological indices HI and CMI were lower (P<0.01) in heat stressed birds compared to control group. Inclusion of vitamin E in combination with Se showed the highest (P<0.01) response in reducing cortisol levels and improving antioxidant and immune status followed by vitamin E sole supplementation. Turmeric supplementation at either dose significantly (P<0.01) lowered serum cortisol and increased the antioxidant activity and immune status. However, the improved response obtained was more significant (P<0.01) with Turmeric supplementation at higher dose (0.4%) than supplementation at lower (0.2%) level. The study indicated that Turmeric at 0.4% level of supplementation to basal diet was effective in lowering the oxidative damage caused due to heat stress, but it was less effective than supplementation of vitamin E either alone (or) in combination with Se.