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

Decreasing methanogenesis in ruminants would benefit the cultural 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 feed supplement has the potential to decrease methanetion as well as increase glucogenesis and hence milk yield, but 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<0.05). Different formulations of encapsulated fumaric acid were also effective. In vivo, growing lambs on a concentrate diet with straw ad libitum produced 24.6L/d of methane, whereas a 100g/kg addition of FA or EFA decreased (P<0.001) methane production to 9.6 and 5.8 L/d, respectively. Live weight gain over 43 d was 184, 165 and 206 g/d (P=0.267) while feed conversion was 135,137 and 159 g gain/kg feed intake (P=0.605) in control, FA and EFA groups, respectively. The 76% decrease in methane described here, one of the largest reported to date, exceeds the inhibition that might be expected from purely stoichiometric considerations, suggesting an adaptive effect on the rumen microbial community. (C) 2009 Elsevier B.V. All rights reserved.