Many contest the problem that arises from the methane released when the planet's zillions of cattle collectively belch, citing a huge contributor to carbon emissions. Since no one can figure out how to make the cows burp less, scientists are now looking to change the consistency of those burps. According to a story in the NY Times, Australian scientists are trying to adapt the cows' burps to match those of the kangaroo.

According to the article, both kangaroos and cows are herbivores and have grass fermenting in their bellies. But for some reason, kangaroo burps contain basically "harmless acids that can be turned into vinegar." 

Researchers are experimenting with food additives in a $28 million Center for Advanced Animal Science, hypothesizing that they can decrease the methane in cows' stomach. The story reports that Australia has a very high per capita rate of greenhouse gas emissions, 10 percent of which come from livestock emissions, including sheep and cattle. The initiative is the beef industry's attempt to solve this problem.

The Times reports "researchers are looking at measures like adjusting diet, managing manure, recalibrating stomach organisms and selectively breeding animals that burp less." In explaining the origins of the methane gas, the article describes how the foregut ferments the grass and releases hydrogen. Certain microbes help the cows release the hydrogen by converting it to methane gas that the animals expel.

This process is different from, say, human digestion in which fermentation takes place in the "hindgut" after the food passes through the stomach. Scientists emphasize the difference between methane from flatulence and methane released from burps. The story quotes lead researcher Athol Klieve, who says, "[the methane] comes from the front end! In the cow, it comes from the front end. But if you're a hindgut fermenter, it goes the other way."

Klieve focuses on kangaroos because they are also foregut fermenters, but their microbes use "acetic acids" to get rid of their hydrogen. Klieve, according to the article, wants to transplant the microbes into cows' stomachs and hopefully reduce the methane output.

There are those who object to the research on the grounds that we could just begin eating kangaroos instead of changing the makeup of cattle. Still others maintain that wild kangaroos could never be managed like livestock to become a main source of meat. According to the story, this hasn't stopped entrepreneurs from trying--kangaroo harvesting businesses are marketing their meat all over Australia as an "alternative, or as a greener, more environmentally aware product."