Growth performance, carcass criteria, and serum biochemical parameters of broiler chickens supplemented with either synbiotic or prebiotic under hot climatic conditions.

1. Two separate experiments were conducted to evaluate the efficacy of either prebiotic or synbiotic on growth performance, carcass yield, organ weights, and serum metabolic profile of broilers under hot climatic conditions. 2. In experiment 1, 150 1-d-old Ross 308 male broiler chickens were fed dietary synbiotic (Biomin® IMBO, 0, 1 or 1.5 g kg-1 of the starter diets and 0, 0.5 or 0.75 g kg-1 of the grower diets) for 6 weeks. In experiment 2, 150 1-d-old Ross 308 male broiler chickens were fed dietary prebiotic (Mannan oligosaccharide 0, 0.5 or 1 g kg-1 of the starter diets and 0, 0.25 or 0.5 g kg-1 of the grower diets) for 6 weeks. Each treatment had 10 replicates containing 5 broiler chickens each. 3. Supplementation of synbiotic at 1 or 1.5 g kg-1 feed to broiler diets during 1-21 d and 0.5 or 0.75 g kg-1 feed, respectively, during 22-42 d improved (P < 0.01) body weight gain, feed conversion ratio (FCR), and decreased (P < 0.01) abdominal fat, serum total cholesterol, and low-density lipoprotein (LDL) cholesterol levels in experiment 1. 4. Similarly, supplementation of the prebiotic at 0.5 or 1 g kg-1 in broiler diets during 1-21 d and 0.25 or 0.50 g kg-1 feed, respectively, during 22-42 d improved (P < 0.01) body weight gain, FCR, and decreased (P < 0.01) abdominal fat, serum cholesterol, and LDL-cholesterol levels in experiment 2.