Comparative analysis of physiological, biochemical and immunological responses to heat stress in hybrid and purebred ducks in tropical environments

Heat stress is a major environmental constraint compromising poultry productivity, welfare, and health in tropical regions. This study evaluated the adaptive responses of five duck genotypes, including local Rupali, a BLRI-improved common duck with white plumage; Pekin, an exotic duck; F1, a crossbred (two-way crossing: Pekin ♂ x Rupali ♀); Muscovy duck, an exotic and H1, the first hybrid (three-way crossing: Muscovy ♂ x Pekin ♂ x Rupali ♀) under heat stress in tropical Bangladesh. A total of 200 ducklings (40 ducklings/genotype) were used in the study and allocated into 4 replicate groups per genotype (10 ducklings/group) housed in individual pens. The ducklings were exposed to elevated temperature in a controlled environmental chamber for 21 days. Respiration and panting rate, skin and rectal temperature, plasma corticosterone, immunological Y and M (IgY, IgM), cholesterol, triglycerides (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), hemoglobin (Hb), heterophil to lymphocyte ratio (H/L ratio), white and red blood cells (WBC and RBC) count parameters were assessed at baseline (day 21), during acute heat stress (day 35), and after prolonged heat stress (day 42) period. Significant genotypic differences were observed in heat tolerance. H1 hybrid ducks exhibited comparatively balanced physiological and biochemical responses relative to the exotic genotypes under heat stress. These findings suggest that heterosis in H1 ducks may support partial metabolic stability and adaptive responses under heat stress conditions. The results support the potential use of H1 hybrids to enhance sustainable duck production in tropical environments.