Appearent digestibility of plant protein based diets by European sea bass Dicentrarchus labrax L., 1758 [Bitkisel protein İçerikli levrek (Dicentrarchus labrax L., 1758) Yemlerinin Görünür sindirilebilirligi]

Commercial culture of carnivorous fish demands the reduction of environmental impact of feeds; that requires minimal use of dietary animal protein. This study investigated the digestibility of diets formulated exclusively out of plant protein, added rendered ingredients and feed attractants, by the carnivore European sea bass, Dicentrarchus labrax. Juvenile European sea bass (14.0±1.0 cm) conditioned to accept artificial dry feed were stocked in polypropylene cages and fed ad libitum in three daily meals, seven experimental diets containing varying levels of vegetable and animal protein sources, added of different feed stimulants. After last daily meal, cages were transferred to cylindrical-conical-bottomed, 200 L aquaria, where faeces were collected by sedimentation into refrigerated containers, preserved and later analysed for chemical composition. Soybean meal can be used as partial substitute of animal protein in diets for European sea bass; the poultry by-product meal shows as a good option as animal protein source in these rations. Control treatment -50PP:50AP- yielded best performances; the requirement for the use of fish meal in the formulation for carnivorous diets is, at least, questionable. Results of the digestibility trials demonstrated the importance of determining the diet digestibility, if precision in the formulation of least-cost feeds for carnivorous fish is the ultimate goal. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey in cooperation with Japan International Cooperation Agency (JICA), Japan