Dietary vitamin B12 requirement and its effect on non-specific immunity and disease resistance in juvenile Chinese mitten crab Eriocheir sinensis

Abstract

article i nfo Article history: An 8-week feeding trial was conducted to investigate the optimum dietary vitamin B12 requirement of juve- nile Chinese mitten crab, Eriocheir sinensis, and its effect on non-specific immunity responses and resistance against Aeromonas hydrophila. Vitamin B12 was supplemented to the basal diet at 0, 0.05, 0.1, 0.2, 0.4, 0.8 and 1.6 mg/kg to formulate seven semi-purified diets. A diet free of vitamin B12 and folic acid was also included as a control. Each diet was fed to E. sinensis (0.051 ± 0.001 g) in four replicates, followed by a challenge study for 2 weeks. Relative growth rate and specific growth rate were best in crabs fed 0.2 and 0.4 mg vitamin B12/kg diets, followed by the 0.1, 0.8, 0, 0.05 and 1.6 mg/kg groups and lowest in the control group (vitamin B12 and folic acid free). Feed efficiency and survival rate peaked at the supplementation of 0.2 mg/kg. The whole body crude protein of juvenile crabs was significantly higher when crabs fed 0.2-0.8 mg vitamin B12/kg than those fed the diets without vitamin B12 supplementation. Total hemocyte count was significantly higher in crabs fed 0.2 and 0.4 mg vitamin B12/kg than those in the other feeding groups, and crabs fed the 0.2 mg/kg diet had the highest phenoloxidase, lysozyme, acid phosphatase and alkaline phosphatase activities but the lowest cumula- tivemortality.Hepatopancreaticvitamin B12concentration increased asthe level ofvitaminB12 supplementation increased. The optimum dietary vitamin B12 requirement by E. sinensis is recommended at 0.20-0.22 mg/kg diet. © 2014 Elsevier B.V. All rights reserved.