Exogenous enzymes supplementation enhances diet digestibility and digestive function and affects intestinal microbiota of turbot (Scophthalmus maximus) juveniles fed distillers' dried grains with solubles (DDGS) based diets

A trial was conducted to evaluate the effect of dietary exogenous enzymes supplementation on apparent digestibility of macronutrients, energy and amino acids, and on digestive enzymes activity and gut microbiota of turbot (Scophthalmus maximus) juveniles fed diets rich in plant feedstuffs. For that purpose, a control diet was formulated to contain circa half protein from fishmeal and the other half from plant feedstuffs (dried distillers' grains with solubles, soybean meal, corn gluten, and wheat gluten). Two other diets were formulated similar to the control but including exogenous enzyme complexes: Synergen® (Alltech; product of solid state fermentation of Aspergillus niger) or Natugrain®TS (BASF; non-starch polysaccharides degrading enzymes complex). Both exogenous enzyme complexes increased the apparent digestibility coefficient (ADC) of dry matter, while the ADC of protein, lipid, and energy were only increased with Natugrain®TS. Moreover, the ADC of methionine, isoleucine, and aspartic acid were increased with both exoenzymes supplementation, while the ADC of lysine and glycine were increased with Synergen® and the ADC of arginine and threonine were increased with Natugrain®TS. Dietary supplementation with Synergen® or Natugrain®TS did not affect intestinal pH but increased the activity of lipase and protease in the posterior intestine, while amilase activity was increased only with Natugrain®TS. Microbiota was also affected by both exoenzymes complexes, increasing its richness and diversity. Present results indicate that diet supplementation with exogenous enzymes complexes, Synergen® or Natugrain®TS, may be a feasible strategy to enhance the digestibility of plant feedstuff-rich diets for turbot juveniles.