Saponins: Effects on Rumen Microbial Ecosystem and Metabolism in the Rumen

Saponins are triterpene and steroidal glycoside compounds in which aglycone (sapogenins) are attached to one or more sugar moieties. They are polar compounds and have great diversity in their chemical structures. Different aqueous or polar solvents have been used to extract saponins. Saponins exhibit several physical and biological properties such as the formation of a stable foam, haemolysis, antimicrobial activity and defaunation of the rumen; however, there is little correlation among these properties. This paper describes the methods of saponin extraction, their chemical diversity and the effects on rumen microbial ecosystem along with metabolism of saponins in the rumen. Recent studies on methane emissions by ruminants provide evidence that saponins may have potential to be used as a antimethanogenic agent; however, the inclusion level of saponin from each source should be tested to get the optimum result. The practical utility of saponins or saponin containing plants as feed additives in sustainable and environmental friendly ruminant production warrants further investigation.