The U.S. Environmental Protection Agency attributes one-fifth of methane emissions to livestock such as cattle, sheep and other ruminants. However, not all ruminants are equal when it comes to greenhouse gas emissions. It turns out that the amount of methane produced varies substantially across individual animals of the same ruminant species.
Sheep image courtesy of AgResearch – Gerry le Roux, Sciencelens. Art by Wayne Keefe, Berkeley Lab Creative Services.