Dietary l-ascorbic acid affects growth, nonspecific immune responses and disease resistance in juvenile grouper, Epinephelus malabaricus

An 8-week feeding trial was conducted to estimate the adequate dietary l-ascorbic acid (AA) requirements of juvenile grouper and its effect on nonspecific immune responses and disease resistance when challenged with Vibrio carchariae. AA supplemented at 0, 20, 50, 80, 150, 250, 400 and 800 mg/kg diet in the basal diet providing of 0, 3, 14, 27, 46, 76, 135 and 288 AA mg/kg diet, respectively. Each diet was fed to triplicate groups of grouper with initial body weight of 7.58±0.05 g. Fish fed diets supplemented with ≥46 mg AA/kg had significantly ( P