Live food mediated vitamin C transfer to Dicentrarchus labrax and Clarias gariepinus

Live food enrichment techniques, using formulated diets and emulsions for improving the nutritional quality of Brachionus and Artemia, were studied as a tool for transferring ascorbic acid (AA) to fish larvae. Artemia nauplii enriched for 24 h with an experimental emulsion containing 20% HUFA and 0%, 10% and 20% ascorbyl palmitate (AP) were administered to catfish larvae in a 20-day feeding trial. Survival was not affected by the dietary AA, but from day 7 onwards a significantly positive effect of supplemental PLA on growth was demonstrated. At the end of the experiment the 20% AP group weighed 30% more than the control (0% AP), i.e. 9.5 and 6.3 mg DW, respectively. Evaluation of the physiological condition was demonstrated by salinity tests. In all three treatments larval growth was relatively low, and it still has to be verified if extra vitamin C in the diet really promotes growth. Seabass larvae fed on AP-enriched rotifers (days 4-12) and Artemia nauplii (days 13-46) showed no significant differences in production characteristics nor in stress resistance, however, for all salinity stress tests the 20% AT group performed better. AA was well incorporated into the predator larvae from the Brachionus feeding onwards.