Influence of olive pomace extract on performance, gut health, immune indices, carcass traits, and meat quality of broiler chickens raised under tropical conditions

This study evaluated the effects of dietary supplementation of an olive pomace extract (OPE), with or without salinomycin, on growth performance, gut health, immune indices, carcass and meat quality in broiler chickens raised under tropical conditions. A total of 1,500 one-day-old male Ross 308 chicks were randomly assigned to six treatments with 10 replicates of 25 birds per replicate in a 3 × 2 factorial design with three levels of OPE (0, 600, or 1,200 ppm) and two levels of salinomycin (SAL; 0 or 66 ppm). Birds were raised during the hot summer season in Thailand for 40 days across three feeding phases. Results revealed that OPE supplementation improved body weight gain (BWG) in a dose-dependent manner, with OPE₁₂₀₀ reducing feed conversion ratio (FCR) at the grower, finisher and overall phases (P < 0.05). Salinomycin supplementation increased BWG while reducing feed intake, FCR, and mortality. SAL and OPE independently enhanced lymphocyte counts (L), and lowered heterophil counts (H) and H/L ratio (P < 0.05). SAL reduced serum fluorescein isothiocyanate-dextran, IL-8, and incidence of foot pad dermatitis (P < 0.05). Neither additive affected gut health indices or carcass traits. OPE₁₂₀₀ reduced drip loss and lipid oxidation and enhanced total, monounsaturated, saturated and polyunsaturated fatty acids in breast meat. No significant interactions between OPE and SAL were observed, indicating independent effects. Overall, OPE and SAL independently enhanced growth performance and immune status, with OPE additionally improving meat quality traits in broiler chickens under tropical conditions.