QUANTIFICATION OF VITAMIN-C REQUIREMENTS FOR JUVENILE SHRIMP (PENAEUS-MONODON) USING POLYPHOSPHORYLATED L-ASCORBIC-ACID

The vitamin C requirements of marine shrimp (Penaeus monodon) for optimal growth were evaluated in a 15-wk feeding trial using polyphosphorylated L-ascorbic acid (C2PP), a stable derivative of L-ascorbic acid (C-1). Juvenile shrimp (0.55 +/- 0.01 g) were fed purified diets containing graded levels (0, 50, 100, 200 and 400 mg/kg diet) of supplemental C2PP or a high dosage of C-1 (2500 mg/kg diet). Their weight gain, survival, feed efficiency and C-1 storage in hepatopancreas and muscle were used to quantify the requirements. The growth of the shrimp fed the unsupplemented diet was significantly lower than those of the supplemented groups except the 100 mg C2PP/kg diet group. The C-1 concentrations in muscle and hepatopancreas were greatest in shrimp fed 200 or 400 C2PP mg/kg diet. The dietary level required for juvenile P. monodon was found to be 209 mg/kg diet, based on the broken-line model analysis of weight gain, and was 220 mg/kg diet and 210 mg/kg diet, based on the analyses of C-1 concentrations of hepatopancreas and muscle, respectively. Shrimp fed unsupplemented diet showed a significantly higher mortality than the supplemented groups. Most of the shrimp in the unsupplemented group that died suffered incomplete molting. No other overt deficiency sign was observed in any group.