The mucosal barriers of fish are an important first line of defense against pathogenic invasion. Functional feed additives such as mannan oligosaccharide (MOS) have the potential to promote improved mucosal physiology and barrier function, which can lead to improved fish robustness, health and welfare. The Atlantic salmon is a valuable production species, with global production exceeding 2.8 million metric tonnes in 2022.
In this study, Atlantic salmon parr (ca. 11.68 ± 0.11g) were fed with either a control diet or diets comprising the same basal formula but supplemented with one of three levels of MOS (0.25%, 0.35% or 0.5% PretegoTM, Greensage Prebiotics Inc) (Table 1). Fish were reared in a freshwater RAS system (16.22 ± 0.16oC) for a period of 70 days, with three replicated tanks per treatment group. At the end of the trial, there were no significant differences between the treatment groups in terms of growth performance and nutrient utilization (Table 2). However, histological appraisal revealed that dietary MOS increased the length of distal intestinal villi and increased the number of goblet cells in the distal intestine and the dorsal region of the skin.
IBW, initial body weight; FBW, final body weight; WG, weight gain; SGR, specific growth rate; FCR, feed conversion ratio; SR, survival rate; C.F, condition factor.
In cloclusion, feeding Atlantic salmon with MOS derived from coconut by products has the potential to improve mucosal barriers. The potential will be further expored in on-going analysis and intestinal microbiome analysis and intestinal and skin gene expression profiling.
Acknowledgements: this research was funded by Enterprise Solutions and Greensage Prebiotics Inc