Quantification of vitamin C requirement for juvenile hybrid tilapia, Oreochromis niloticus X Oreochromis aureus, with L-ascorbyl-2-monophosphate-Na and L-ascorbyl-2-monophosphate-Mg

A growth experiment was conducted to quantify the level of L-ascorbyl-7-mon ophosphate-Na (C2MP-Na) to satisfy the dietary vitamin C requirement for ju venile hybrid tilapia. L-Ascorbyl-2-monophosphate-Mg (C2MP-Mg) was also inc luded in the study for comparison. Purified diets with six levels of ascorb ic acid (0, 30, 50, 70, 90 and 120 mg/kg diet) from either supplemental C2M P-Na or C2MP-Mg were each fed to triplicate groups of fish (mean initial we ight: 1.22 +/- 0.07 g) for 8 weeks. Fish fed greater than or equal to 38.97 mg C2MP-Na/kg diet and greater than or equal to 22.92 mg C2MP-Mg/kg diet g ained significantly (P < 0.05) more body weight than fish fed the unsupplem ented diet. Hepatic ascorbate concentrations in fish generally increased as the dietary ascorbate level increased. Results of the broken Line analysis indicated that the adequate dietary ascorbic acid From each source for gro wing fish is 63.4 mg of C2MP-Na/kg (equivalent to 15.98 mg of ascorbic acid /kg) diet and 40.5 mg of C2MP-Mg/kg (equivalent to 18.82 mg ascorbic acid/k g) diet, and it also indicated that C2MP-Mg was about 85% as effective as C 2MP-Na in meeting the vitamin C requirement for tilapia. (C) 1999 Elsevier Science B.V. All rights reserved.