L.E.C. Conceicao, H. Grasdalen
Optimisation of the composition of fish diets is closely dependent on the appropriate balance of the different amino acid (AA), and in particular the essential amino acids (EAA). Dietary AA imbalances will bring an unavoidable AA loss, and thereby sub-optimal growth. The EAA profile of fish carcass or muscle is generally considered to be a good index of the qualitative EAA requirements in fish. However, this is a rough estimate, which may be erroneous when there are differences in the bioavailability of the different AA. Such differences can occur due to differential digestion/absorption or catabolism of the individual AA. In this study, a preliminary investigation was done on the bioavailability of individual AA, when Artemia nauplii are fed to post-larval turbot (Scophthalmus maximus L.). Specific activities (nmol 13C/micromol AA) in the individual AA were compared in both turbot and Artemia, using high resolution H-NMR and 13C-NMR spectroscopy and also HPLC. The possibilities of using HMR techniques to study AA metabolism, and in particular bioavailability are discussed. The quantification of AA by H-NMR spectroscopy and by HPLC is compared. The estimated bioavailabilities of the different AA are discussed in light of the turbot and Artemia AA profiles.
(CCMAR Centro de Ciencias do Mar, Universidade do Algarve, Campus de Gambelas, 8000 Faro, Portugal)