I have to jump in on this one.

I agree, deer can and do eat grass. Studies haveshown that it makes up about10-15% of their diet.However as previously stated, the cell walls contain high amounts of lignin which is hard for the bacteria in the rumen to break down. Deer just don't have a large enough rumen to keep mature grass long enough to break down and extract the nutrients. They can readily eat and digestyoung green grasses. However, they can starve to deathwith a stomach full of mature grass. This is why you probably see them more often eating grass in a regularly mowed lawn. Same goes for cows, moderate grazing keeps grass in a growing state and therefore easier to digest.