不同饲料维生素C水平对口黑鲈仔鱼生长、免疫、抗氧化能力的影响

通过研究不同饲料维生素C(VC)含量对大口黑鲈仔鱼生长、免疫和抗氧化能力的影响,探究其维生素C最适需求量,为维生素C在大口黑鲈仔鱼饲料中的应用提供科学依据。实验设计5个实验组,分别为0(VC0)、200(VC200)、400(VC400)、800(VC800)和1600(VC1600)mg/kg。以出膜后11日(体重为1.2±0.3 mg)的大口黑鲈仔鱼为研究对象,在工厂化循环水系统进行为期3周的投喂实验。结果表明：大口黑鲈仔鱼的终末体重、增重率、特定生长率均随饲料中维生素C添加水平的提高先升高,其中VC400组数值最高。通过折线模型分析维生素C添加水平与增重率的关系,大口黑鲈仔鱼饲料中维生素C最适添加水平为421.2 mg/kg。各组生长激素和类胰岛素生长因子1的mRNA表达水平的变化趋势和生长性能基本一致。各维生素C添加组的补体浓度无显著差异,但都显著高于VC0组,补体C3与补体C4浓度均在VC1600组达到最大值。在溶菌酶含量中,VC400组、VC800组与VC1600组含量无显著差异,显著高于VC0组与VC200组。各组过氧化氢酶活性、谷胱甘肽含量、超氧化物歧化酶活性均随添加水平的提高先升高,均在VC400组取得最大值。各组的碱性磷酸酶活性和体内维生素C含量随饲料维生素C添加量的升高而升高,丙二醛含量随饲料维生素C添加量的升高而降低。综上所述,饲料中添加420mg/kg维生素C可以有效提高大口黑鲈仔鱼的生长性能、免疫性能和抗氧化性。

Effects of dietary vitamin C levels on growth performance, immunity and antioxidant capacity of largemouth bass (Micropterus salmoides) larvae

An 3-week feeding trial was conducted to determine the optimal dietary vitamin C requirement of largemouth bass larva (1.2 ± 0.3 mg). Five practical diets were formulated to contain 0 (V0), 200 (V200), 400 (V400), 800 (V800) and 1600 (V1600) mg/kg vitamin C. Each experimental diet was fed to triplicate groups of fish to apparent satiation seven times a day. At the end of the experiment, the results showed that the final body weight, weight gain rate and specific growth rate increased with the increase of dietary vitamin C level, and then tended to be stable, with the highest value in VC400 group. Weight gain rate (WGR) and specific growth rate (SGR) markedly increased with increasing dietary vitamin C supply and then leveled off while body ASA concentration continued increase with increasing dietary vitamin C supply. Vitamin C supplementation not only increased antioxidant capacities (activity of catalase (CAT), reduced glutathione content (GSH), Superoxide dismutase (SOD) and immunocompetence(complement C3, complement C4 and Lysozyme(LZM) concentration) of the larva, but also decreased lipid peroxidation (malondialdehyde (MAD) concentration) in the body. Broken-line analysis showed that the optimal dietary vitamin C requirement of largemouth bass was 421.2 based on WGR. In a practical production of largemouth bass larva, 420 mg/kg of dietary vitamin C should be recommended to maintain normal physiological function.