Its all to do with the four stomachs. They eat grass which is mostly cellulose and cows cant digest this. So they eat it and I think it ferments in the first stomach (not to sure about this) where all the bacteria get to it.... these break down the food into substances the cow can digest (fatty acids) and rebuild it into a protein. The red clover in their diet also makes it harder to digest making them chew longer which then makes it more nutritious.