Effect of dietary zinc and α-tocopheryl acetate on broiler performance, immune responses, antioxidant enzyme activities, minerals and vitamin concentration in blood and tissues of broilers

• Positive interaction between zinc and α-tocopheryl acetate supplements on reduction of lipid oxidation.
• Positive impacts of zinc and α-tocopheryl acetate supplements on humoral and cellular immune responses.
• An increase in activity of Glutathione peroxidase and Superoxide dismutase enzymes in response to α-tocopheryl acetate supplement.

A total of 1350 one-day-old male broilers were allocated to nine dietary treatments in order to evaluate the effects of organic zinc (Zn) and α-tocopheryl acetate (α-TOA) supplements and their interaction on fatty acids profile, oxidation resistance state, vitamins and minerals concentrations in blood, liver, breast and thigh muscles. Three levels of dietary supplemental Zn (0, 50 and 100 mg/kg of diet) and three levels of α-TOA (0, 150 and 300 mg/kg of diet) were combined as a completely randomized design with 3 × 3 factorial arrangement. An increase in Zn supplementation enhanced Zn (P < 0.005), vitamin A (P < 0.05) and α-tocopherol (α-TO) (P < 0.005) concentrations in serum along with a reduction in iron (P < 0.005), copper (P < 0.005) and augmentation in humeral immune responses (P < 0.01). In addition, an increase in dietary Zn supplementation led to an increase in Zn (P < 0.005) and α-TO deposition (P < 0.05) in the liver, breast and thigh muscles. Dietary α-TOA supplementation resulted in an increase in serum vitamin A and α-TO (P < 0.005) and a reduction in malondialdehyde (MDA) concentration (P < 0.001) along with an improvement in antioxidant enzyme activities (P < 0.05). In addition, α-TOA supplements altered humoral and cellular immune responses and alleviated lipid oxidation in the liver, breast and thigh muscles (P < 0.005). The interaction of Zn and α-TOA reduced MDA generation in the breast and thigh muscles as well as serum and the liver (P < 0.005), in which supplementation of Zn could reinforce the effects of α-TOA supplement in reducing lipid oxidation. Overall, supplementation of 100 mg Zn/kg of diet and 300 mg α-TOA/kg of diet would alleviate lipid oxidation in broiler tissues along with increase in humoral and cellular immune responses without any adverse effect on fatty acids profile of meat.