Influence of water temperature on protein requirement and protein utilization in juvenile sea bass, Dicentrarchus labrax

Abstract

Protein requirements of juvenile sea-bass, Dicentrarchus labrax, were estimated at two different water temperatures, 15°C and 20°C. The influences of dietary protein level and water temperature on body composition, weight gain, food and nutrient utilization were studied. Protein requirements were different depending on whether weight or body protein gain was used as the criterion. The optimal protein concentration for weight gain was similar at both temperatures, and was close to 50%, but daily protein requirement and food intake were both lower at 15°C than at 20°C. When body protein retention was used as the criterion, the protein requirement as a percentage of dry diet was estimated to be 40% at 20°C, whereas at 15°C there was no clear optimum. A diet with 50% protein and 15% starch produced the best weight gain and food conversion rates at 15°C and 20°C. Nevertheless, from nutrient and energy utilization data, a diet with 40% protein and 27% starch could be a better standard diet for sea bass at both temperatures tested.