Effects of Dietary Vitamin C on the Physiological Responses and Disease Resistance to Ph Stress and Aeromonas Hydrophila Infection of Megalobrama Amblycephala

摘要

We evaluated the effect of vitamin C (Vit C) supplementation on the resistance of Megalobrama amblycephala to Aeromonas hydrophi1a infection under pH stress. Fish were randomly divided into six groups: a control group (fed with a basal diet) and five treatment groups (fed with basal diet supplemented with 33.4, 65.8, 133.7, 251.5 and 501.5 mg/kg Vit C, respectively). After 90 days, fish were exposed to combined stressors, first pH 9.5 followed by A. hydrophila infection. The results showed that 133.7 mg/kg vit C improved complement 4 (C4), anti-superoxide anion free aradical (ASAFER) and heat shock protein (HSP) 70 compared with the control group; and 251.5 mg/kg vit C enhanced complement 3 (C3), HSP60, HSP70 and HSP90 compared to the control group before stress. After pH stress and A. hydrophila infection, hemoglobin, ASAFER and HSP60, HSP70, HSP90 in the groups fed with 133.7 and 251.5 mg/kg vit C were still significantly higher, while serum cortisol in the group fed with 251.5 mg/kg vit C was lower compared to the control group 15 days after pH stress. The cumulative mortality of the control group was higher than that of the five treatment groups at 12, 24 h after A. hydrophila infection. The results of this study suggest that 133.7- 251.5mg/kg vit C in a diet could have potential to stimulate immune response, and enhance resistance against high pH stress and A. hydrophila infection of Wuchang bream.