Functional roles of mannan and chitosan oligosaccharides on animal health and nutrition: A review

Mannan-oligosaccharides (MOS) and chitosan-oligosaccharides (COS) are low-molecular-weight carbohydrates with 2 to 20 monosaccharides associated with glycosidic bonds positioned among monosaccharides and polysaccharides. They promote growth, regulate immunity, enhance gut microbiota structure, and exhibit anti-inflammatory and antioxidant properties. Due to the worldwide enforcement of antibiotic restriction policies, oligosaccharides (Olig) have garnered increased attention as novel green feed supplements. Based on how they digest, they can be put into two groups: functional COS and MOS, which are not easily absorbed and have specific physiological roles, and widespread Olig, like sucrose and maltose, which are easily absorbed by the intestine. The prevalent functional Olig comprise COS, MOS, fructo-oligosaccharides (FOS), and xylo-oligosaccharides (XOS), among others. Functional MOS and COS serve as a superior functional feed base, acting as nutritional fiber and prebiotics to enhance the diet, optimize gut microecology, and provide anticancer, antioxidant, anti-inflammatory, and lipid-lowering effects. This review examines the varieties of functional MOS and COS, their utilization in animal and poultry feeding, and the variables that have constrained their effectiveness in this century. This review establishes the theoretical foundation for upcoming studies on multifunctional MOS and COS and the prospective use of substitute antibiotics in the livestock and poultry sectors.