The fast food company Burger King wants to change the way cows eat in an effort to limit climate change. The restaurant chain said it is adding a different plant, called lemongrass, to the diet of cows that provide meat for the restaurant group. The fast food chain announced the Reduced Methane Emissions Beef Whopper on Tuesday. The hamburger is made with beef from cows that release less methane gas, the company says. The burgers will be available in Los Angeles, Miami, New York City, Austin, Texas and Portland, Oregon for a limited time.