Cell wall components of Saccharomyces cerevisiae (rich in β-1,3 and -1,6-glucans and mannan oligosaccharides) in isolated or whole forms have been shown to confer immunomodulatory effects in fish. These benefits are at least partially induced by improvements of intestinal health. Despite the reported benefits, many knowledge gaps exist with regards to the optimal form and dosage.
Histological appraisal revealed that fish fed the WYCW treatment had a 39% increase (P = 0.0422) in goblet cell abundance in the distal intestine and that the PβG treatment-fed fish had a 49% increase (P = 0.0459) in goblet cell abundance in the skin when compared to the control group.
In addition, transmission electron microscopy (TEM) analysis of the distal intestine revealed significantly different microvilli morphometrics. Fish fed the PβG treatment had significantly longer (P < 0.0001) and more densely packed (P = 0.0001) microvilli than the other treatment groups. Fish fed the WYCW treatment had significantly denser microvilli arrangement (P = 0.0056) than the control group.
Ongoing analysis includes gene expression profiling of immunomodulatory and barrier function genes.
In conclusion, both dietary products demonstrated the potential to enhance the epithelial barriers studied.
An experiment was conducted to investigate the efficacy of highly purified β-glucans (PβG) and whole yeast cell walls (WYCW) to enhance the mucosal health of Atlantic Salmon (Salmo salar) parr. A total of 120 parr (ca. 21g) were randomly assigned into six experimental units (20 per tank) and fed either 1] Control (no yeast additives), 2] PβG (0.02% Leiber® Beta-S) or 3] WYCW (0.2% Biolex® MB40) treatments for 4 weeks. All treatments were fed to the same % of biomass (between 1.5% and 2% per day). At the end of the experiment, there were no significant differences in zootechnical performance (weight gain, SGR and FCR) between fish fed the different diets.