L-ascorbyl-2-sulfate alleviates Atlantic salmon scurvy

Area of Science:

• Aquaculture Nutrition
• Fish Physiology
• Vitamin C Metabolism

Background:

• Atlantic salmon (Salmo salar) require dietary vitamin C for optimal health.
• Ascorbic acid (C1) is unstable and may not be an adequate vitamin C source for fish.
• Alternative vitamin C forms like ascorbyl-2-sulfate (C2S) and ascorbyl-2-monophosphate (C2MP) are being investigated for aquaculture.

Purpose of the Study:

• To evaluate the efficacy of L-ascorbic acid (C1), L-ascorbyl-2-sulfate (C2S), and L-ascorbyl-2-monophosphate (C2MP) as vitamin C sources for Atlantic salmon.
• To determine the minimum effective dietary level of C2S for preventing and recovering from vitamin C deficiency (scurvy) in salmon.

Main Methods:

• Duplicate groups of 150 Atlantic salmon fry were fed diets supplemented with varying levels of C1, C2S, or C2MP for 12 weeks.
• Negative control groups received no vitamin C.
• Scorbutic fish were subsequently fed recovery diets containing different levels of C2S or C2MP.

Main Results:

• Negative control fish developed clinical signs of scurvy, including reduced growth and skeletal deformities.
• Dietary supplementation with C2S (50 mg/kg or higher) or C2MP supported normal growth and prevented scurvy.
• Fish fed C2S during recovery showed complete restoration of health and normal tissue vitamin C levels.

Conclusions:

• Ascorbyl-2-sulfate (C2S) is an effective and stable vitamin C source for Atlantic salmon, promoting normal growth and preventing scurvy.
• C2S can be used at levels of 50 mg/kg or higher to ensure adequate vitamin C status in farmed salmon.
• L-ascorbic acid (C1) and L-ascorbyl-2-monophosphate (C2MP) also supported normal growth, but C2S demonstrated particular efficacy in recovery from deficiency.