Methane gas generated by grazing animals, and the problems associated with it are well documented. But a new study into how much methane is produced by camels reveals that the humped mammals don't create as much methane as ruminant animals such as cows and sheep.

Currently about 20 percent of global methane emissions stem from ruminants, according to the University of Zurich, but little is known about the methane emissions from other animal species.

By studying the methane emissions of camels, a team of University of Zurich researchers hoped to get the facts straight about camel methane emissions.

Camels, alpacas and llamas - much like cows - have multi-chambered stomachs forestomachs used to regurgitate food. These animals produce methane by burping and through their excrement. It has long been assumed that camels produce a similar amount of methane to cows and sheep.

A study by the Zurich researchers has determined that, in absolute terms, "camels release less methane than cows and sheep of comparable body size." However, when comparing methane production with the amount of converted feed, it is the same for both camels and ruminants.

The researchers learned that camels have a lower metabolism, which necessitates less need for food and therefore leads to lower methane production than cows or sheep. The camel's lower metabolism could also help explain why the animals thrive in areas prone to food shortages.

"To calculate the proportion of methane produced, different estimated values should be used for camels than those used for ruminants," said University of Zurich's Marcus Clauss.

Clauss and his collaborators contend that their findings may play an important role in calculating "methane budgets" in countries that have many camels, "such as the dromedaries in the Middle East and in Australia, or the alpacas and llamas in various South American countries."

The researchers report their findings in the journal PLOS One.