Kangaroos Are Methane Gas Producers

Knowing that methane production is dramatically affected by the length of time that a meal takes to pass through an animal and that food passes through well-fed kangaroos faster than through hungry animals, Munn and Clauss chose to feed alfalfa to the animals at two different levels (a restricted diet versus all they could eat) to find out how that affected the animals’ methane production.

When digesting plant-based foods animals, known as ruminants – cows, sheep and kangaroos, for instance – produce methane gas which contributes to global warming, say many experts.

“The idea that kangaroos have unique gut microbes has been floating around for a few time and a great deal of research has gone into discovering these apparently unique microbes”, said study co-author Adam Munn, a professor in the School of Biological Sciences at the University of Wollongong in Australia. “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.

During this last study a group of researchers dedicated themselves to recording everything that kangaroos ate and expelled in order to work out the amount of methane produced by their farts. An ETHZ research project is also looking into this question.

Researchers fed alfalfa to individual kangaroos housed at the New South Wales’ Fowlers Gap Research Station.

They also found that kangaroos who eat more food produce less methane.

Munn and Clauss were critical of efforts to try to reduce greenhouse gas emissions from cows and sheep by replacing their gut fauna with that from kangaroos or other low-methane emitting animals. Methane is less abundant in the atmosphere than carbon dioxide, but it is more effective at trapping heat (infrared radiation). Worldwide, 28 per cent of all greenhouse gas emissions come from livestock. Now a team of scientists in Australia have studied kangaroo farts and their contribution to climate change. Exactly why kangaroos produce less methane, however, remained a mystery. Meanwhile, the scientists measured the methane accumulating in each kangaroo’s room and analyzed their poop. The bacteria then produce more methane per food intake.

All of this suggests that the different amounts of methane emitted by the three species of ruminents results from conditions under which the intestinal bacteria break down food products.

It may still be the case that kangaroo guts actually do hold special secrets, the researchers said. It’s still less than many other grazing animals, though, the researchers say.