L-ASCORBYL-2-SULFATE HAS EQUAL ANTISCORBUTIC ACTIVITY AS L-ASCORBYL-2-MONOPHOSPHATE FOR TILAPIA, OREOCHROMIS-NILOTICUSXO-AUREUS

A growth experiment was conducted to compare L-ascorbyl-2-sulfate (C2S ) and L-ascorbyl-2-monophosphate (C2MP) with L-ascorbic acid (C1) for supplying the dietary vitamin C requirements for juvenile tilapia, Ore ochromis niloticus x O. aureus. Purified diets with 6 levels of asscor bic acid (0, 30, 50, 70, 90 and 120 mg/kg diet) from either supplement al C1, C2S or C2MP were fed to tilapia (mean initial weight 1.53 +/- 0 .17 g) for 10 week. Each diet was fed to 3 replicate groups of fish. F ish fed the diet lacking supplementary vitamin C had poor growth, low feed efficiency ratio (FER), reduced appetite, hemorrhages around the fins and darker skin compared to vitamin C supplemented groups. Weight gains were significantly (P < 0.05) higher in fish fed diets containi ng 23.56, 40.51-68.85 or 37.28 and 75.25 mg of ascorbic acid/kg from C 1, C2S or C2MP, respectively, than those fed the unsupplemented contro l diet. Ascorbate concentrations in liver, muscle and plasma were high er in fish fed diets supplemented with C1, C2S or C2MP than those fed the unsupplemented control diet and the concentrations were generally proportional to the level of ascorbic acid supplementation in the diet . Vertebral collagen concentrations were higher in fish fed diets cont aining > 7.68, > 40.51 or > 37.28 mg ascorbic acid/kg diet from C1, C2 S or C2MP, respectively, than those fed the unsupplemented control die t. Weight gain and vertebral collagen content analyzed by broken-line regression indicated that the adequate dietary ascorbic acid from each source for growing tilapia is about 41-48 mg of C2S/kg (equivalent of 19-23 mg ascorbic acid/kg) diet and 37-42 mg of C2MP/kg (equivalent o f 17-20 mg ascorbic acid/kg) diet.