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

Requirements for dietary energy and protein in growing fish can be quantifi ed 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 temperatur e 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 f ish weight and increased from 5.4 to 10 MJ kg(-1) body mass, whereas the pr otein 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)(-0.6 9) day(-1) for energy and protein, respectively. The efficiencies of utiliz ation of digestible energy (DE) and digestible protein (DP) for maintenance and growth in D. labrax were determined by feeding fish of various sizes a t increasing feeding levels, from zero to maximum voluntary feed intake. DE intake and the subsequent energy gain were measured. The relationship betw een 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 mai ntenance was calculated to be 43.6 kJ BW (kg)(-0.79) day(-1) and for digest ible protein 0.66 g BW (kg)(-0.69) day(-1). The partial efficiency of utili zation for growth was 0.68 and 0.52 for digestible energy and digestible pr otein, respectively. Using these values allows optimization of practical feeding at different gr owth rates for D. labrax culture. (C) 2001 Elsevier Science B.V. All rights reserved.