L-ascorbyl-2-sulfate alleviates Atlantic salmon scurvy

Duplicate lots of 150 Atlantic salmon (Salmo salar), average weight 0.5 g, were fed NRC diet H-440 base containing L-ascorbic acid (C1) or L-ascorbyl-2-sulfate (C2S); or L-ascorbyl-2-monophosphate (C2MP): at 0 or 100 mg C1; 50, 100, 300 mg C2S; or 50, 100 mg C2MP per kg dry diet in 12 degrees C freshwater tanks. After 12 weeks, negative controls (no vitamin C) exhibited reduced growth, scoliosis, lordosis, and petechial hemorrhages typical of fish scurvy. All other lots grew normally. Four 100-fish lots of scorbutic salmon, average weight 3.3 g, were placed on recovery diets of 0, 50, or 300 mg C2S, or 100 mg C2MP per kg dry diet. After 5 weeks, fish fed either level of C2S intake had recovered and resumed growth. Negative controls continued to develop acute scurvy. The 41 survivors in this no-vitamin-C group all had advanced scurvy, whereas all fish in both C2S-fed recovery groups appeared normal. Tissue assays for C vitamers disclosed normal levels of C1 and C2S in the recovery groups. All other test treatment lots containing C1, C2S, or C2MP had fish with normal appearance and no significant differences in growth response for the 17-week test period. C2S at 50 mg or more per kg diet as the sole vitamin C source promoted normal growth in young Atlantic salmon for more than 20-fold increase in weight.