Effect of protein-lipid content in enrichment products for live preys on larval and post-larval performance of gilthead seabream

Since artificial feed formulation is yet available to completely substitute for rotifers and Artemia, feeding live prey to young fish larvae still remains essential in commercial hatchery operations. The nutritional quality of rotifers and Artemia strains being relatively poor in eicosapentaenoic acid (EPA, 20:5n-3) and especially docosahexaenoic acid (DHA, 22:6n-3), it is essential and common practice to enrich these live prey with enrichment products containing high levels of essential nutrients for larvae at early life stages. As the rotifers and Artemia are filterfeeding organisms, they are incubated in aqueous media where the enrichment products is dispersed, consequently facilitating its incorporation through the passive filtering behaviour of them. The enrichment products have significant levels of highly polyunsaturated fatty acids (HUFA), vitamins and free amino acids on the early development of marine fish larvae which are essential for marine fish larvae. In the present study, two rotifers enrichments products were used (DHA protein selco and SKR-Medium) in the first part of the study, in which larvae fed rotifers enriched with these products till 18 day after hatching (dah). There was no significant difference (P>0,05) between the two rotifers treatments in dietary lipids content in dry basis and protein contents and consequently there was no significant difference between the two treatments in the survival and growth of larvae. In the second part it depended on feeding the larvae with Artemia enriched with four enrichments products: 1. Easy A1 DHA Selc; 2. SKR-Medium; 3. SKR-High Protein; 4. SKR-High Lipid. The study showed that the larvae fed Artemia SKR-High Lipid, the highest survival and the smallest growth, while the larvae fed Artemia SKR-High Protein is the highest growth. There is no significant difference in the survival of larvae fed Easy A1 DHA Selco, SKRMedium and SKR-High Protein. There is no significant difference between the four dietary Artemia in the larvae dry weight. In conclusion, the experimental enrichment products of rotifers and Artemia used in the study are adequate for gilthead seabream larvae development