OPTIMIZATION OF DIETARY VITAMIN-C IN FISH AND CRUSTACEAN LARVAE - A REVIEW

HPLC techniques were adapted and standardized for quantification of as corbic acid (AA) and its derivatives in both diets and target organism s. To assess the dietary needs for AA at start of exogenous feeding, t he AA content in the various live diets currently used in aquaculture (algae, rotifers, Artemia) was analyzed. Application of techniques for boosting vitamin C using ascorbyl palmitate as the source enabled the transfer of elevated levels (up to 2500 mu g AA/g DW) of bioactive vi tamin C. Larvae of fish (Clarias gariepinus, Dicentrarchus labrax, Sco phthalmus, maximus), white shrimp (Penaeus vannamei) and prawn (Macrob rachium rosenbergii) were enriched via the live food chain. This vitam in C enrichment procedure has proven to be a valuable technique for th e evaluation of the effects of high levels of dietary vitamin C on str ess resistance. However, in most of the species examined, the initial level of AA in Brachionus and Artemia impaired the determination of th e AA requirements for optimal growth and survival. Formulated diets co ntaining variable levels of stable;AA-phosphate esters were used for t he determination of minimal requirements for AA in the early post-wean ing stage of marine fish species (D. labrax, S. maximus) and the postl arval stage of penaeid shrimp (Penaeus monodon, P. vannamei). For both fish species, results indicated that, within the concentration range tested, 20 mg AA/kg diet is sufficient for normal growth and survival. For production of postlarval shrimp, this level amounted to a minimum 20 and 130 mg AA/kg diet for P. monodon and P. vannamei, respectively , while a level of 2000 mg AA/kg diet was needed to enhance the resist ance of shrimp postlarvae to stress conditions and bacterial infection s. (C) 1997 Elsevier Science B.V.