Apparent nutrient digestibility and gastrointestinal evacuation time in European seabass (Dicentrarchus labrax) fed diets containing different levels of legumes

Abstract

Nutrient digestibility and gastrointestinal evacuation time for diets containing two levels of legumes were determined in European seabass (initial wt. 150 g). Seven isonitrogenous (44 g crude protein 100 g- 1) and isoenergetic (20 kJ g- 1) extruded diets were tested. Experimental diets contained 15 g or 30 g 100 g- 1 of each legume including faba bean meal, (FB15, FB30), chickpea meal (CP15, CP30), field pea meal (FP15, FP30) and a control, wheat meal containing, diet. Inclusion of faba beans in diets significantly enhanced apparent digestibility coefficients (ADCs) of dietary protein and energy at both inclusion levels. Starch digestibility was significantly lower for the control and FP30 diet and significantly higher for the FB15 diet. Fat digestibility coefficients were elevated significantly for FB15, FB30, CP15, FP15 and FP30 diets, compared to the CP30 and the control diet. The incorporation of faba bean and chickpea greatly affected gastrointestinal evacuation time compared to fish fed the control diet. Longer passage times were observed when these legumes were included in the diet. Glucose serum peak value was delayed for FB30 and a slower decreasing rate was observed for the legume diets. The addition of legumes had a positive effect on physical properties of the pellets by increasing the hardness while water activity remained within the safety limits. The findings of this study suggest that the legumes tested are potential candidates for carbohydrate replacement (wheat) and, to a lesser extent, for protein substitution in diets for European seabass.