Nutrient digestibility, digestive enzymes activity, bile drainage alterations and plasma metabolites of meagre (Argyrosomus regius) feed high plant protein diets supplemented with taurine and methionine

Abstract

The supplementation effect of a high plant protein diet with methionine and taurine on nutrient digestibility, digestive enzymes activity, plasma and intestine bile acid content, and plasma metabolites was assessed in meagre juveniles. A control (CT) diet was formulated with 42% crude protein and 18% lipids, and including only 10% fishmeal, corresponding to 18% of the dietary protein level. Three other diets were formulated similar to the control but supplemented with 0.26% methionine (MET), 1.0% taurine (TAU), or 0.26% Met plus 1.0% Tau (MET+TAU), in a 2 × 2 factorial design. Final dietary Met levels were 0.75 and 1.0%, and Tau levels were 0.10 and 1.20%. Diets were fed to triplicate groups of 103 ± 21.2 g fish, twice a day, to apparent satiation. Fish were assembled in fiberglass tanks (60 L of water capacity), each one with feces settling column. Dietary Met supplementation increased apparent digestibility of dry matter, protein, lipids, and energy while dietary Tau supplementation increased lipids digestibility. Lipase activity was not affected by dietary methionine level, but it was higher in fish fed the taurine supplemented diet at the higher methionine level. Proteases and amylases activities were not affected by diet composition. Total bile acid in plasma and anterior intestine increased with dietary Tau supplementation. Dietary Tau supplementation also increased plasmatic levels of cholesterol, total proteins, and triglycerides. Overall, results of this study indicate that dietary methionine supplementation improved diet digestibility and that dietary taurine supplementation improved lipid digestibility and positively affected lipid metabolism in meagre.