There are many environmental problems associated with ruminant livestock and these problems continue to grow as the demand for meat-rich diets increases around the world. One of the biggest problems is that cows emit methane through eructation (or belching) as they chew their cud. Methane is a powerful greenhouse gas, some 25 times more potent at trapping heat than carbon dioxide. More than a quarter of all human-originated methane going into the atmosphere comes from raising livestock.