中文摘要：

本试验旨在研究维生素C对半滑舌鳎在感染迟缓爱德华氏菌后红细胞抗氧化能力及葡萄糖-6-磷酸脱氢酶（G-6-PD）活性的影响。在基础饲料中添加L-抗坏血酸-2-磷酸酯（作为维生素C添加剂）,制成维生素C含量分别为0.2（对照）、104.8、209.6、313.8、521.6、837.3 mg/kg的6种试验饲料。将健康的半滑舌鳎[平均体重（99.12±1.58）g]分别喂食上述6种饲料84 d后,感染迟缓爱德华氏菌,试验期为14 d。结果显示：试验鱼的终末体重、特定生长率、增重率均以209.6 mg/kg组最高。随着饲料中维生素C含量的升高,半滑舌鳎血浆维生素C含量及红细胞血红蛋白（Hb）含量和G-6-PD活性均呈上升趋势,且除104.8 mg/kg组红细胞G-6-PD活性外各添加组均显著高于对照组（P〈0.05）。饲料维生素C含量为209.6 mg/kg时,红细胞超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性显著高于对照组（P〈0.05）,而后随着维生素C含量继续升高,红细胞SOD和CAT活性呈下降趋势。对照组红细胞丙二醛（MDA）含量和红细胞膜一氧化氮（NO）含量显著高于各添加组（P〈0.05）。以上结果表明,维生素C能有效降低感染迟缓爱德华氏菌半滑舌鳎的红细胞氧化损伤程度;经过折线模型分析,推荐饲料中维生素C含量为257.04-341.36 mg/kg。

英文摘要：

This study was conducted to investigate the effects of vitamin C on red blood cell（ RBC） antioxidation capacity and glucose-6-phosphate（ G-6-PD） activity of tongue sole（ Cynoglossus semilaevis）. Six experimental diets were prepared with vitamin C content of 0. 2（ control）,104. 8,209. 6,313. 8,521. 6 and837. 3 mg / kg in form of L-ascorbyl-2-polyphosphate,respectively,and those diets were fed healthy tongue sole [average body weight of（ 99. 12 ± 1. 58） g] for 84 days. After feeding trial,The test fish were challenged with Edwardsiella tarda for 14 days. The results showed as follows： the highest values of final body weight,special growth rate and weight gain rate were found in the 209. 6 mg / kg group. With the dietary vitamin C content increasing,the vitamin C content in plasma,and hemoglobin（ Hb） content and G-6-PD activity in RBC all showed an increasing tendency,and all additional groups were all significantly higher than the control group（ P〈0. 05） except RBC G-6-PD activity in 104. 8 mg / kg group. The SOD and CAT activities in RBC in 209. 6 mg / kg group were significantly higher than those in the control group（ P〈0. 05）,and then the activities decreased with continued to increase the dietary vitamin C content. The malondialdehvde（ MDA）content in RBC and nitric oxide（ NO） in RBC membrane in the control group were significantly higher than those in all additional groups（ P〈0. 05）. The results indicate that the vitamin C can effectively reduce the oxidant damage of RBC of tongue sole with Edwardsiella tarda infection. The suitable dietary vitamin C content is257. 04 to 341. 36 mg / kg which estimated by broken-line models.