Effect of Cyclic Heat Exposure on the Growth Performance and Metabolism of Broilers Fed Palm Kernel Meal

The aim of this study was to evaluate the interaction between heat stress (HS) and the incorporation of palm kernel meal (PKM) in broiler chicken diets, as well as their effects on growth performance and metabolism. A total of 288 21‐day‐old male Arbor Acres chicks were used in a 21‐day experiment. The birds were randomly assigned to two temperature conditions: thermoneutral (TN; 23°C) and HS (33°C for 9 h per day). Each group received one of two diets (P0: 0% PKM; P1: 10% PKM) in a 2 × 2 factorial design, with environment (TN vs. HS) as the first factor and diet (P0 vs. P1) as the second. Each treatment included six replicates. The results showed that HS increased cloacal temperature ( p < 0.05). Serum CK concentrations were not affected by treatment ( p > 0.05), but an interaction was observed for serum corticosterone ( p = 0.0049). In contrast, analysis of serum oxidative stress revealed no differences in CAT or SOD activity ( p > 0.05), whereas GSH‐Px, T‐AOC, and malondialdehyde levels were influenced by treatment ( p < 0.05). Examination of tight junction proteins in the jejunum indicated no effects of temperature or diet ( p > 0.05), although an interaction was found for claudin‐1 gene expression ( p = 0.026). Finally, analysis of the cecal microbiota showed that temperature increased the relative abundance of several bacterial species ( p < 0.05), whereas dietary treatment affected only the Phocaeicola species ( p < 0.05). In summary, PKM supplementation did not mitigate the adverse effects of HS.