Optimization of dietary vitamin C in fish and crustacean larvae: a review

Abstract

HPLC techniques were adapted and standardized for quantification of ascorbic acid (AA) and its derivatives in both diets and target organisms. To assess the dietary needs for AA at start of exogenous feeding, the 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 μg AA/g DW) of bioactive vitamin C. Larvae of fish ( Clarias gariepinus, Dicentrarchus labrax, Scophthalmus maximus), white shrimp ( Penaeus vannamei) and prawn ( Macrobrachium rosenbergii) were enriched via the live food chain. This vitamin C enrichment procedure has proven to be a valuable technique for the evaluation of the effects of high levels of dietary vitamin C on stress resistance. However, in most of the species examined, the initial level of AA in Brachionus and Artemia impaired the determination of the AA requirements for optimal growth and survival. Formulated diets containing variable levels of stable AA-phosphate esters were used for the determination of minimal requirements for AA in the early post-weaning stage of marine fish species ( D. labrax, S. maximus) and the postlarval 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 resistance of shrimp postlarvae to stress conditions and bacterial infections.