A group of scientists and farmers in northern New England is working on a plan to feed seaweed to cows to gauge whether it can help reduce greenhouse gas emissions that contribute to climate change. The concept has gained traction in recent years after some studies showed the potential of seaweed feeds to cut back on methane. About a quarter of the methane in the country comes from cows, which produce the gas when they belch or flatulate. One of the big questions is which kinds of seaweed offer the highest benefit to farmers looking to cut methane. Researchers hope to find out.