Faster digestion in kangaroos reduces methane emissions

Date:  November 5, 2015

Source:  University of Zurich

Animals produce methane during the digestion process -- some more than others. Currently, around 20 percent of the world's methane emissions stem from ruminants. If this gas is released into the atmosphere, it aggravates the greenhouse effect and aids global warming. Previous studies revealed that ruminants, which include cows and sheep, release more methane into the environment than kangaroos, for instance -- even though the latter also possess a foregut, where bacteria break down the plant fibers and produce methane (much like in a cow's rumen). Exactly why kangaroos produce less methane, however, remained a mystery. The belief was that a different intestinal flora composition to a cow's was responsible.

Researchers from the University of Zurich, ETH Zurich and the University of Wollongong in Australia have now studied the previous assumptions from a different angle. The team measured how much methane kangaroos emit per food intake. "If you consider the absolute volume of methane per body size, kangaroos produce about as much as horses or ostriches -- i.e. significantly less than cows," explains Marcus Clauss from the University of Zurich. "If the gas production is correlated with the amount of food ingested, however, the amount of methane is higher and therefore closer to the ruminants again. In other words, the digestion process itself in kangaroos is not all that different to a cow's."

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