Chromium and alpha-lipoic acid supplementation improved performance, antioxidant status, and immunity of broiler chickens under heat stress

Abstract

Heat stress is one of the most important challenges facing the poultry industry, affecting the performance, antioxidant status, and immune response of broiler chickens. This study evaluated whether dietary chromium propionate (CrPr) and alpha-lipoic acid (ALA) improve broiler performance, antioxidant status, and immune responses under both normal and heat-stress conditions. Heat stress was imposed from Day 24 to Day 42 at 35 ± 2°C. In total, 576 as-hatched Ross 308 chicks were assigned to a 3 × 2 × 2 factorial design, combining three doses of CrPr (0, 750, and 1500 μg/kg) with two doses of ALA (0 and 300 mg/kg). Under normal temperatures, the highest average weight gain and the lowest feed conversion ratio were observed in birds receiving 750 μg/kg CrPr with 300 mg/kg ALA (P ≤ 0.05). The lowest abdominal fat was observed in heat-stressed broilers given 1500 μg/kg CrPr plus 300 mg/kg ALA (P ≤ 0.05). Heat stress reduced blood antioxidant enzyme concentrations compared with normal temperatures (P ≤ 0.05). ALA at 300 mg/kg lowered triglycerides, cholesterol, and glucose under heat stress (P ≤ 0.05). Triglycerides and superoxide dismutase were highest under normal temperatures with 1500 μg/kg CrPr plus 300 mg/kg ALA (P ≤ 0.05). For heat-stressed groups, the combination of 750 μg/kg CrPr and 300 mg/kg ALA produced the highest glutathione peroxidase activity (P ≤ 0.05), and antibody titers against sheep red blood cells at Day 28 were highest with 300 mg/kg ALA under heat stress (P ≤ 0.05). Simultaneous 750 μg/kg CrPr and 300 mg/kg ALA improved broiler feed conversion, antioxidant status, and lipids. Implementing this targeted CrPr–ALA supplementation could be a practical, feed-based approach for poultry industries aiming to maintain productivity and health during summer or high-heat management conditions, although further work may be warranted to confirm dose scalability, cost-effectiveness, and consistency across different breeds, farm environments, and stress durations.