Australian scientists say they're hoping to breed sheep that burp less as part of their latest efforts to tackle climate change.
When sheep belch they produce a greenhouse gas called methane, which adds to global warming.
So scientists have been carrying out experiments to find a biological reason why some sheep burp less than others.
Experts say livestock are responsible for more than half the greenhouse gases produced by agriculture in Australia.
And a staggering 90% of the methane that animals like sheep, cows and goats produce, is released by burping.
So far, tests on the sheep have found that the more they eat, the more they burp.
But scientists say there are still big differences between individual animals.
Once they've worked out what causes those differences, it's hoped they'll be able to breed greener and less windy sheep.