Optimization of feeding regimes for European sea bass Dicentrarchus labrax:: a factorial approach

Requirements for dietary energy and protein in growing fish can be quantified using the factorial approach, which assumes that the requirement is the sum of growth and maintenance. Thus dietary intake can be calculated using the respective partial efficiencies of utilization. Growth for Dicentrarchus labrax as a function of body weight and temperature was predicted by the equation: y = 0.64 X BW (kg)(0.587) x exp(0.07 X T) (where y = weight gain in g fish(-1) day(-1), BW = body weight in kg and T = temperature in T). The composition of the gain was measured by analyzing whole fish ranging from 1 to 400 g. The energy content was dependent upon fish weight and increased from 5.4 to 10 MJ kg(-1) body mass, whereas the protein content remained constant at 171 g kg(-1). The comparative slaughter technique was used to determine the loss in the fish during starvation and the values amounted to 33.7 kJ BW (kg)(-0.79) day(-1) and 0.39 BW (kg)(-0.69) day(-1) for energy and protein, respectively. The efficiencies of utilization of digestible energy (DE) and digestible protein (DP) for maintenance and growth in D. labrax were determined by feeding fish of various sizes at increasing feeding levels, from zero to maximum voluntary feed intake. DE intake and the subsequent energy gain were measured. The relationship between DE intake and energy gain was found to be linear and was independent of feed intake and body weight. The requirement for digestible energy for maintenance was calculated to be 43.6 kJ BW (kg)(-0.79) day(-1) and for digestible protein 0.66 g BW (kg)(-0.69) day(-1). The partial efficiency of utilization for growth was 0.68 and 0.52 for digestible energy and digestible protein, respectively. Using these values allows optimization of practical feeding at different growth rates for D. labrax culture. (C) 2001 Elsevier Science B.V. All rights reserved.