Effects Of Dietary Copper And Immunological Stress On Antioxidant Capability Of Broiler Chickens

Three experiments were conducted to investigate the effects of dietary copper and immunological stress on the antioxidant capability of broiler chickens.In experiment 1, the broiler chicks were fed with three different diets containing 0, 8 and 50 mg/kg copper respectively besides the basal level of 6.5mg/kg from one day old till the end of the experiment. The growth performance data were recorded weekly during the first three weeks. The results showed that the supplementation with 50 mg/kg Cu significantly improved growth performance compared with the supplementation of 8mg/kg, which further demonstrates that copper may work as a growth promoter.In experiment 2, 48 day-25 chicks with uniform weights were selected from each group in Experiment 1. The chicks in each group were fed with the same levels of copper as their former ones and were divided into two subgroups. On day 25, the chicks in one subgroup from each group were injected with LPS at hour 0, while the ones in other subgroup were injected with saline at the same time. The weight gains, feed intakes and cloacal temperatures were recorded and blood samples were obtained from six birds of each treatment in every diet group at hours 0, 12, 24 and 72 after the injection. The activities of enzymatic antioxidants of erythrocyte CuZn-SOD, CAT and GSH-Px, the levels ofnon-enzymatic antioxidants of plasma total antioxidant power (FRAP), ceruloplasmin (Cp), uric acid (UA) and the levels of plasma non-esterified fatty acid (NEFA), glucose and lipid peroxidation (TBARS) were examined. One-time injection of LPS affected the growth performance of chicks treated with 8mg/kg copper significantly and influenced cloacal temperatures and Cp levels significantly as well. Dietary copper had significant effects 'on the levels of plasma Glu, UA and FRAP. Neither LPS-injection nor dietary copper had significant effects on plasma TBARS.In experiment 3, 48 day-25 chicks with uniform weights were selected from each group in Experiment 1. The chicks in each group were fed with the same levels of copper as their former ones and were divided into two subgroups. On day 25, the chicks in one subgroup from each group were injected with LPS at hours 0, 24 and 48, while the ones in other subgroup were injected with saline at the same time interval. The cloacal temperatures were recorded and blood samples were obtained from six birds of each treatment in every diet group at hours 0, 24, 48 and 72 after the first injection. The activities of enzymatic antioxidants of erythrocyte CuZn-SOD, CAT and GSH-Px, the levels of non-enzymatic antioxidants of plasma FRAP, Cp, UA and the levels of plasma NEFA, Glu and TBARS were examined. Three-time injection of LPS lowered the growth performance of chicks treated with Omg/kg or 50mg/kg copper significantly and influenced temperature, NEFA, UA, Cp, GSH-Px and FRAP significantly, while the dietary concentration of copper imposed significant effects on temperature, plasma Glu, NEFA, UA, FRAP and TBARS and erythrocyte CuZn-SOD and GSH-PxCu. Three-time injection tended to increase plasma TBARS of the chicks and dietary copper had significant effects on plasma TBARS of the experimental birds.