Amino acid profiles of meagre (Argyrosomus regius) larvae: Towards the formulation of an amino acid balanced diet

Abstract

Abstract The indispensable amino acid (AA) profile of fish carcass has been commonly used to estimate the AA requirements of fish. In this study the AA composition of whole body tissue of meagre, Argyrosomus regius , was determined at 0, 3, 6, 8, 12, 17, 20, 24, 30 and 39 days after hatching (DAH). Several differences were observed during meagre larval ontogeny with the AA profile at 0 DAH being different from the remaining larval ages and with a change occurring around 12 and 17 DAH which was reflected in some AA such as arginine, valine and tyrosine. Meagre and diet AA profiles were compared and several AAs were found to be in apparent deficiency in the diets. In rotifers a lower number of AA were apparently in deficiency but the correlation between larval and diet AA profiles was low (R 2 lower than 0.7). Although a higher number of AA were apparently in deficiency in Artemia and dry feed, the correlations obtained were high (R 2 above 0.75). Histidine appeared to be the limiting AA in all diets. These results suggest that the higher nutritional imbalances in meagre larval ontogeny occur during the first 10 days of feeding when larvae are fed on rotifers. To solve these apparent nutritional imbalances, an alternative to rotifers should be found or at least a reduction of the period when larvae are fed on rotifers alone. Given the potential of meagre to aquaculture, the use of suitable diets for this species should be formulated. The results obtained in this study can be used to formulate AA balanced diets which are expected to increase growth and decrease larval mortality. Statement of relevance The main aim of this work was to obtain an estimation of the amino acid profile of meagre larvae. In addition, a comparison of larval amino acid profile and diet was done to identify potential deficiencies. There are no available data on AA requirements of meagre larvae and the diets used for larval rearing are those used in seabream rearing. Meagre and seabream larvae have a very different growth pattern and, according to our experience the former has a considerably higher demand of protein. Meagre and seabream have distinct AA profiles too (as observed in this study). Given that meagre is the species with the highest potential to be intensively farmed in the Mediterranean region it is important to formulate specific diets for this species. The results obtained in this work could be the basis for the formulation of amino acid balanced diets.