Improved growth performance, digestive ability, antioxidant capacity, immunity and Vibrio harveyi resistance in coral trout (Plectropomus leopardus) with dietary vitamin C

Abstract

An 8-week growth trial was conducted to assess the effects of dietary vitamin C (VC) on the growth performance, digestive enzyme activity, antioxidant ability, immunity, and resistance to Vibrio harveyi infection of coral trout (Plectropomus leopardus, initial weight 17.42 ± 0.06 g). Four kinds of iso-nitrogenous and iso-lipidic experimental feeds were formulated with covering VC levels of 0 (C0), 50 (C1), 100 (C2), and 200 (C3) mg/kg, respectively. Supplementation of an appropriate amount of VC in diet (a) increased specific growth rate (SGR) and weight gain rate (WGR); (b) increased amylase, lipase, and trypsin activities in the liver; (c) enhanced glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities, and reduced malonic dialdehyde (MDA) level in serum and liver; (d) increased lysozyme (LZ) and acid phosphatase (ACP) activities in serum and liver, as well as complement (C3 and C4) and immunoglobulin M (IgM) contents in the liver; (e) upregulated the relative expression of copper-zinc superoxide dismutase (SOD-1), manganese superoxide dismutase (SOD-2), CAT, GSH-Px1a, ACP6, AKP, LZ-c, IgM, C3, and C4-b in the liver; (f) improved the survival rate of V. harveyi challenge. In summary, an appropriate amount of VC could improve growth, digestive ability, antioxidant capacity, immunity, and the ability to resist the challenge of V. harveyi in coral trout. In order to ensure that coral trout has good growth performance, digestive and antioxidant capacity, it is recommended that the levels of VC in the feed is between 255.25 and 273.84 mg/kg. The immunity of coral trout is stronger when the VC level in the diet is between 251.95 and 314.03 mg/kg.

Keywords

• Growth performance
• Immunity
• Oxidation resistance
• Vibrio harveyi
• Vitamin C