Guardian: McDonald’s has long been the butt of jokes about what goes into its burgers, but now it is to spend thousands of pounds investigating what comes out of its beef cows. The fast food chain, which uses beef from 350,000 cattle a year for its burger meat, is to conduct a three-year study into methane emissions from cattle on 350 farms across Britain. Gas produced by flatulent livestock accounts for 4% of the UK’s total carbon emissions. It is 23 times more powerful than carbon dioxide as …