Effects Of Different Antioxidants On Antioxidant Ability, Immune Functions And Related Gene Expressions In Yellow-Feathered Broilers

Objective:In this experiment we studied the effect of microbial antioxidant and lipoic acid on growth performance, antioxidant ability, immune functions as well as related gene expression in broiler chickens. The objective is to investigate the regulation mechanism of antioxidants on immune functions in broilers from organs, cell and molecular levels. The results would provide theoretical evidence on new methods of enhancing immune functions based on free radical biology in broiler production.Method:One hundred and twenty 21-day-old broiler chickens with the close body weight were randomly divided into four groups, with 5 replicates of 6 broilers each replicate. The control group was fed basal diet; trail group 1 was fed basal diet supplemented with 0.5% microbial antioxidant; trail group 2 was fed basal diet supplemented with 300mg/kg lipoic acid; trail group 3 was fed basal diet supplemented with a composite antioxidant including 0.5% microbial antioxidant and 300mg/kg lipoic acid.Result:Microbial antioxidant, lipoic acid and its composite antioxidant had no significant effect on growth performance of broilers. On the 15th day of the trail, compared with control group, all the three antioxidants could significantly increased the activity of total superoxide dismutase (P<0.05); microbial antioxidant and composite antioxidant improved the activity of scavenging·OH (P<0.05); all the three antioxidants significantly increased the content of IgG (P<0.01); while microbial antioxidant and lipoic acid could improve the lymphocyte proliferation by ConA and spleen indices, respectively (P<0.05); composite antioxidant increased the rate of transformation of lymphocyte and content of IL-2 (P<0.05).On the 30th day of the trail, compared with control group, all antioxidants could significantly increase the activity of scavenging·OH (P<0.01); microbial antioxidant and lipoic acid decreased the content of H2O2 and malondialdehyde (P<0.01); all the three antioxidants could improve the content of IgG (P<0.05);while microbial antioxidant and lipoic acid could significantly increase the indices of spleen,bursa of fabricius and the rate of transformation of lymphocyte (P<0.05); composite antioxidant increase the content of IL-2 (P<0.05). All the three antioxidants could significantly improve the expression of IL-2 mRNA and IL-6 mRNA, and the combination of microbial antioxidant and lipoic acid had a significantly combined effect. There was a significant correlation between indices of antioxidant and immune functions. The correlation between the activity of scavenging·OH and index of spleen, the activity of scavenging·OH and IgG content, the activity of SOD and IgG content were all positively correlated (P<0.05); Content of H2O2 and IgA were negative correlativity (P<0.05).Conclusion:Microbial antioxidant and lipioc acid can clear the free radicals, increase antioxidant ability, improve immune function and promote the IL-2,IL-6 mRNA expression. There was a significant correlativity between antioxidant ability and immune functions.