Improved glucose and lipid metabolism in European sea bass (Dicentrarchus labrax) fed short-chain fructooligosaccharides and xylooligosaccharides

• First study about prebiotics and glucose metabolism in fish
• XOS decreased lipogenesis and improved fish growth performance.
• XOS and scFOS increased glycolytic activity in fish fed fish meal diets.
• XOS and scFOS improve glucose and lipid metabolism in European sea bass.

The effects of short-chain fructooligosaccharides (scFOS) and xylooligosaccharides (XOS) on growth, feed utilization and liver activity of key enzymes of glycolytic, gluconeogenic, and lipogenic pathways were studied in European sea bass juveniles. This is the first study about the effect of prebiotics on fish glucose metabolism and few and contradictory studies are available about prebiotic effect on lipid metabolism.Fish were fed isoproteic (46%) and isolipidic (15%) diets based on fish meal (FM diets) or plant ingredients (PP diets; 30 FM:70 PP) as main protein sources. Four other diets were formulated similar to the control diets (PPC; FMC) but including 1% scFOS or 1% XOS (PPFOS, PPXOS, FMFOS and FMXOS diets). Growth performance was higher in fish fed PPXOS diet than PPC diet. No effect of dietary prebiotics on feed efficiency was noticed. Glucokinase activity was higher in fish fed FMFOS and FMXOS diets than FMC diet. Lipogenic enzyme activities (malic enzyme, fatty acid synthetase, glucose-6-phosphate dehydrogenase) were lower in fish fed diets including XOS than in the other groups. Glycolytic (glucokinase, pyruvate kinase) and lipogenic enzyme activities were higher, and gluconeogenic (fructose-1,6-bisphosphatase) enzyme activity was lower in fish fed FM diets than the PP diets. Overall, dietary XOS decreased lipogenesis, independently of dietary protein source, and improved growth performance in fish fed PP diets. In fish fed FM diets, XOS and scFOS increased glycolytic activity. XOS seemed to have good potential to be used as prebiotic in European sea bass.