Effect of different dietary vitamin E levels on growth, fish composition, fillet quality and liver histology of meagre (Argyrosomus regius)

Abstract

Seven experimental isonitrogenous (50%) and isolipidic (16%) diets with different levels of α-tocopherol acetate (16, 100, 190, 285, 430, 880 and 1300 mg kg−1) were tested during 72 days to evaluate growth performance, tissue composition, fillet oxidation and liver histology in meagre juveniles, Argyrosomus regius. Growth performance, feed conversion ratio (FCR) and tissue composition were similar among treatments (P>0.05). In the liver, no major differences were recorded in lipid and fatty acid composition but higher lipid vacuolization were observed in diets E100, E190 and E880. Muscle fatty acid profiles showed an increment of the highly unsaturated fatty acid (HUFA) and a decrease of the saturated fatty acid with the increase of dietary vitamin E, which was accompanied with a reduction of the muscle TBARS responses.  Therefore, is suggested that diets for this species should be supplemented with 451mg kg−1of DL-α-tocopherol acetate (496 UI of vitamin E), as determine by broken-line regression analysis of muscle TBARS, to provide good overall growth performance and improved fish quality and storage stability. Moreover, results suggest that vitamin E deficiency or excess may deteriorate fish health.  Statement of relevance  The optimization of the dietary vitamin E level will contribute to formulate a suitable diet for meagre, a candidate for European aquaculture diversification, that until now is being fed with diets specific for other species. This study will narrow the knowledge gap that exists regarding meagre nutritional needs.