Marine by-products and insects as a potential chitosan source for ruminant feed additives

Chitosan is a hydrophilic polysaccharide produced from chitin that has a wide range of applications. Chitosan has several functions as an anti-microbial, methane reducer, and protein protective agent. Based on this function chitosan has been explored for its potential as a feed additive. Moreover, source and extraction technique have potentially affected the yield and degree of deacetylation (DD) of chitosan products. The present review provides information on various chitosan isolation processes in marine by-products and insects and the result of their DD and yield. Chemical isolation processes are still popular in industries compared with biological processes based on their DD and yield. Chitosan properties and yield from insects are comparable with those of commercial chitosan derived from a marine by-product. The application of chitosan as a feed additive is also highlighted in this review. Moreover, chitosan as a feed additive has the capability to decrease CH4 production, increase propionate production, reduce the acetate/propionate ratio, and improve nutrient utilization efficiency, and animal performance. Chitosan has the potential to be a beneficial natural and plentiful feed additive, particularly for reducing enteric methane emissions.