Re-evaluation of the Optimum Dietary Vitamin C Requirement in Juvenile Eel, Anguilla japonica by Using L-ascorbyl-2-monophosphate.

This study was conducted to re-evaluate the dietary vitamin C requirement in juvenile eel, Anguilla japonica by using L-ascorbyl-2-monophosphate (AMP) as the vitamin C source. Five semi-purified experimental diets were formulated to contain 0 (AMP0), 30 (AMP24), 60 (AMP52), 120 (AMP108) and 1,200 (AMP1137) mg AMP kg-1 diet on a dry matter basis. Casein and defatted fish meal were used as the main protein sources in the semi-purified experimental diets. After a 4-week conditioning period, fish initially averaging 15±0.3 g (mean±SD) were randomly distributed to each aquarium as triplicate groups of 20 fish each. One of five experimental diets was fed on a DM basis to fish in three randomly selected aquaria, at a rate of 3% of total body weight, twice a day. At the end of the feeding trial, weight gain (WG) and specific growth rate (SGR) for fish fed AMP52 and AMP108 were significantly higher than those recorded for fish fed the control diet (p<0.05). Similarly, feed efficiency (FE) and protein efficiency ratio (PER) for fish fed AMP52 were significantly higher than those for fish fed the control diet (p<0.05). Broken-line regression analysis on the basis of WG, SGR, FE and PER showed dietary vitamin C requirements of juvenile eel to be 41.1, 41.2, 43.9 and 43.1 (mg kg(-1) diet), respectively. These results indicated that the dietary vitamin C requirement could range from 41.1 to 43.9 mg kg(-1) diet in juvenile eel when L-ascorbyl-2-monophosphate was used as the dietary source of vitamin C.