Kangaroos aren't as free from gas as scientists initially thought.
The Australian marsupials were once thought to be less gassy than cows and sheep, and that by replacing the latter two as primary sources of protein, humans can reduce methane gas emissions by cooking and consuming kangaroo meat.
A new study found, however, that while kangaroos do emit low emissions of methane, this rate is not any lower than other non-ruminant herbivores.
Researchers believe that previous studies focused on looking for methane gas emissions orally rather than from the rear, where kangaroos were found to produce more methane gas.
"With kangaroos, most of the methane comes out the back end, not the front end like you're used to seeing in sheep and cattle," Munn explained, adding that by focusing on the rear, the scientists found the methane gas from kangaroos previous studies missed.
Upon hearing that kangaroos produce less gas than ruminants, scientists are continuously researching on the possible cause and how it could be applied to other livestock.
Munn and his associates believe that the lower methane emission from kangaroos may have something to do with its digestive system. In ruminant herbivores, their food goes through a long digestive process, including microbial fermentation. However, in kangaroos, the digestive process is shorter and microbes don't have time to fully grow.
"It's like the environment in the kangaroos' fore-stomach is almost like a new environment every time, whereas in something like a sheep or a cow, it's like a really well established forest," Munn said.
Based on these findings, researchers are now planning to design food sources for kangaroos that can be quickly and easily digested to further lower their methane gas production.
They found that the amount of food kangaroos ate affected their methane production rate. When the kangaroos were put into captivity as part of the experiment and fed a restricted diet for several days, the marsupials' methane gas production increased.
This proved that aside from giving animals food that is faster to digest, adequate food intake must also be ensured to prevent microbes in the animals' guts to break the plant material into methane gas.