Improved disease resistance in sea bass (Dicentrarchus labrax) fed mannan oligosaccharides (MOS)

Abstract

The objective of this study was to determine the effect mannan oligosaccharides derived from the outer cell wall of a select strain of Saccharomyces cerevisiae(Bio-Mos,Alltech Inc,USA) on the potential mechanisms related to improved disease resistance and in relation to a stress challenge on European sea bass(Dicentrarchus labrax).Specimens of 40g at initial density of 4.1 kg/m3 were fed for 8 weeks 4‰dietary MOS inclusion.Weight gain,specific growth rate,mucus production,gut and head kidney prostaglandins levels and microbiota profiles were evaluated. Growth and gut mucus production increased when MOS was supplemented.After the feeding trial, fish were subjected to a direct gut inoculation with the pathogen Listonella anguillarum in combination to a stress panel.Results showed a significant reduction(P≤0.05) on mortality, different patterns of mortality and a significant reduction in the grade of pathogen infection when fish were supplemented with MOS.Prostaglandins production and microbiota profiles were accordingly affected.These results suggest that MOS supplementation increases disease resistance when supplemented before a disease challenge test and this fact could be related with the stimulation of intestinal mucus secretion.The interactions of MOS with the secretory activity of goblet cells could represent new interesting possibility for the manipulation of their important protective function.