Intestinal gas is produced by microbes that live in the gut. Most people are concerned about their own gas, but it's a livestock gas known as methane that has scientists concerned. Cows, goats, and sheep require symbiotic microbes to help digest the plant biomass that they eat, and some of these microbes make the methane. Globally, livestock are one of the largest sources of methane production, and the third largest source of this greenhouse gas in the United States. Trying to curb methane emissions has become a topic of interest. And that interest has led to Australian wallabies. Wallabies are marsupial mammals like kangaroos and eat diets high in vegetation. Like cows, they have multiple compartments in their digestive tracts, including one that metabolizes plant matter to break it down. To digest that food, the compartment needs microbes.