The problem with being a cow is you have to eat all the time just to stay alive. The problem with being a cow farmer is that you need a lot of land so that your cows can keep eating.
Scientists think they might have a solution to both issues, by engineering a cow superfood of more digestible grass. In doing so, they could make bioethanol power stations more efficient too.
Grass, which includes crops such as rice, sugar cane and wheat, is extremely successful in part because it is so difficult to digest. It has evolved robust cell walls that make it hard to eat, making it less desirable to herbivores. This is why humans do not use it in salads and why animals