مشخصات پژوهش

A total of 360 male broiler chickens (Ross 308) were used in a 3 × 3 factorial arrangement of treatments consisting of 3 concentrations of NVC (0, 50 and 100 mg/kg of diet) and 3 concentrations of NZnO (0, 30 and 60 mg/ kg of diet) with 4 replicates of 10 broiler chickens each. Broiler chickens were reared under normal condition until d 25 and after that the heat stress (34 ± 2◦C) was applied for eight hours (0900 to 1700 h) from d 25 to 42. Body weight gain (BWG) and feed intake (FI) were measured weekly and feed conversion ratio (FCR) was calculated on pen basis. At d 42, all broiler chickens of each pen were individually weighed and the mean value of the pen weight was recorded then one broiler chicken weighing close to the mean weight of the pen was randomly selected, blood sampled and slaughtered for carcass measurements. There was an interaction (P≤0.01) between NVC and NZnO on BWG, FCR and relative weight of liver with the greatest BWG (P≤0.001), improvement in FCR (P≤0.01) and relative weight of spleen (P≤0.001) in broiler chickens fed the diet containing 100 mg NVC/kg diet with 60 mg NZnO/kg diet. Supplementation of diet with NVC linearly increased (P≤0.01) BWG. NZnO had a quadratic effect (P≤0.001) on BWG. Inclusion of NVC and NZnO had a quadratic effect (P≤0.01 and P≤0.05 respectively) on FCR. Vitamin C nano particles and NZnO linearly and quadratically (P≤0.001) increased the relative weight of liver. There was an interaction effect of NVC and NZnO on relative weight of thigh (P≤0.05), spleen, bursa and jejunum (P≤0.001). NVC linearly increased relative weight of carcass and spleen (P≤0.05) and had a quadratic effect on relative weight of bursa (P≤0.01). Supplementation of the diet with 50 mg NVC/kg diet and 60 mg NZnO/kg diet had the greatest effect on villus height and width, and on crypt depth (P≤0.05). Nanoparticles of NVC and NZnO linearly and quaratically (P≤0.01) increased villus height, crypt depth, and villus height: crypt depth. The interaction of NVC and NZnO on red blood cell (RBC) count was significant with broiler chickens receiving the diet supplying 100 mg NVC//kg diet with 30 or 60 mg NZnO/kg diet having the greatest number of RBC(P≤0.001). Nano zinc oxide linearly (P≤0.001) increased glutathion peroxidase concentration. It was concluded that supplementation of the diet with 100 mg of NVC/kg diet plus 60 mg of NZnO/kg diet can improve growth performance, glutathione peroxidase activity, immune function and carcass characteristics in broiler chickens under heat stress conditions.