Amino acid levels from blood plasma of rainbow trout raised in different seasons and farming systems

Abstract

Climate change and large variations in medial parameters over the last decades, question the future of salmonid farming. For this, recirculating aquatic systems (RAS) have been developed, that artificially provide medial parameters at optimal values. To optimize these aquatic systems, fish are reared at high densities (50-100 kg / m 3 of water). From this point of view, due to high growth densities, the quality and biological value of trout meat can be depreciated. The results of our study show a relatively constant level of essential amino acids (EAA) and non-essential (NEAA) regardless of season for rainbow trout raised in RAS compared to those raised in the classic system. With small exceptions, both for EAA and NEAA, their values regardless of the season were higher in the case of RAS compared to the classic growth system. High level of valine (Val E Autumn 168.40 ± 1.14 μg / ml) is highlighted for the EAA compared with the level obtained in winter in the classical system (Val C Winter 105.40 ± 1.72 μg / ml). In NEAA, very high values were obtained for alanine (Ala E Autumn 117.60 ± 0.56 μg / ml) as compared to the same amino acid values in the winter season in the classical growth system (Ala C Winter 74.53 ± 0.67 μg / ml). The seasonal variations of EAA and NEAA in classical trout are due to environmental conditions, especially temperature, which influence the voluntary ingestion of feed, trout being poikilotherm organisms. Optimal media parameters in recirculating systems contribute to a higher biological value of trout, highlighted by the increased and constant level of EAA and NEAA.