Tannins to make cows on pasture more climate-friendly What if you could reduce methane emissions by graze cows on fields with tannin-rich plants? This could be cheese, dairy products and meat," explains Assistant Professor Carsten Stefan Malisch from the Department of Agroecology at Aarhus University. Cows on pasture are the main focus of the new Sapere Aude project. "Tannins can interact with microbes in the soil and in the digestive system of cows. So, our expectation is that when cows eat these plants with the grass, the tannins will reduce methane production in the cows' digestive systems," he says, adding that the tannin plants have another very big advantage.