Encapsulated fumaric acid as a feed ingredient to decrease ruminal methane emissions

Abstract Decreasing methanogenesis in ruminants would benefit the agricultural industry because it would lead to lower energy losses from the animals as well as being beneficial for the environment in decreasing emissions of a greenhouse gas. Fumaric acid (FA) as a feed supplement has the potential to decrease methane production as well as increase glucogenesis and hence milk yield, but the quantity fed has to be restricted because of a risk of acidosis and a consequent decrease in fibre breakdown and feed intake. The objective of this study was to determine if FA encapsulated in partially hydrogenated vegetable oil (PHVO) could decrease methane formation without the problematic effects on ruminal pH. A commercial sample of encapsulated fumaric acid (EFA) did not affect pH and maintained propionate production when added in vitro to ruminal fluid from sheep receiving 49:51 grass hay:concentrate, and it suppressed methane formation by 19% (P In vivo , growing lambs on a concentrate diet with straw ad libitum produced 24.6 L/d of methane, whereas a 100 g/kg addition of FA or EFA decreased (P