Digestibilité des protéines et disponibilité des acides aminés de quelques matières premières chez le bar (Dicentrarchus labrax)

Abstract

Protein digestibility of soyabean meal (SM), a casein-gelatin mixture (CGM) and fish hydrolysate (FH) was estimated in European sea bass reared in the laboratory using increasing substitution levels of a reference diet based on Norwegian fishmeal with protein digestibility 91%. With increasing substitution, digestibility increased for CGM and decreased for SM. Digestibility of FH diets was similar to that for the reference diet. The standard error for digestibility coefficients tended to increase with the level of substitution for SM and to a lesser extent for FH. Regression between the coefficient of apparent digestive utilization and the level of substitution was linear for CGM and SM. Values for the apparent availability of amino acids of the different protein sources are tabulated. For some amino acids values were different from those for total N suggesting that availability of essential amino acids should be used in feed formulation. Coefficients of true availability estimated from faecal N and amino acids using a protein-free diet were not significantly different from apparent availability coefficients.