The effect of vitamin C on stress withstanding capability in the juvenile soft-shelled turtle (Pelodiscus sinensis)

The study was conducted to determine the effect of dietary supplementation of vitamin C on anti-acid stress ability in juvenile soft-shelled turtle. The soft-shelled turtles were fed vitamin C supplemented diets at levels of 0, 250, 500, 2500, 5000 and 10 000 mg kg(-1) for 4 weeks. The results showed that the phagocytic rate of blood cell in the group fed vitamin C deficient diets, the serum bacteriolytic activity in the two groups fed vitamin C supplemented diet at 0 and 250 mg kg(-1) and the serum bactericidal activity in all groups after acid stress significantly decreased compared with those of before stress (P < 0.1). The phagocytic rate of blood cells in the two groups fed vitamin C supplemented diet at 2500 and 5000 mg kg(-1) were significantly higher than those of the four groups fed at 0, 250, 500 and 10 000 mg kg(-1) (P < 0.01). The serum bacteriolytic activity in the groups fed vitamin C supplemented diet at 500, 2500, 5000 and 10 000 mg kg(-1) were significantly higher than that of the group fed vitamin C deficient diets (P < 0.05), and the two groups fed vitamin C at 2500 and 5000 mg kg(-1) were significantly higher than those of the groups fed at 250 and 10 000 mg kg(-1) (P < 0.05). The serum bactericidal activities in the four groups fed vitamin C supplemented diet at 500, 2500, 5000 and 10 000 mg kg(-1) were significantly higher than those of the two groups fed at 0 and 250 mg kg(-1) diet (P < 0.01), and the two groups fed vitamin C at 2500 and 5000 mg kg(-1) were significantly higher than those of the two groups fed at 500 and 10 000 mg kg(-1) (P < 0.1). These results suggest that supplementation of vitamin C higher than 250 mg kg(-1) is necessary to reduce the adverse effects of acid stress.