AMYLASE AND TRYPSIN RESPONSES TO INTAKE OF DIETARY CARBOHYDRATE AND PROTEIN DEPEND ON THE DEVELOPMENTAL STAGE IN SEA BASS (DICENTRARCHUS-LABRAX) LARVAE

Sea bass (Dicentrarchus labrax) larvae were fed from day 15 to day 35 with 4 isoenergetic formulated diets that varied in protein (30, 40, 5 0, 60%) and carbohydrate (37, 27, 17, 7%) content. The diets were desi gnated as P30, P40, P50 and P60, respectively. Best growth and surviva l were noted for P50 larvae. Poor growth and survival were observed fo r P30 larvae. The specific activity of amylase increased in direct rel ation to the dietary carbohydrate level from day 18 onwards. This incr ease was the result of extensive amylase synthesis. Trypsin activity w as positively correlated with dietary protein level only at day 35. Th is study shows that the mechanisms involved in amylase regulation are efficient in very young sea bass larvae, while those related to trypsi n appear later in ontogeny and thus suggests an age-dependent regulati on of enzyme synthesis.