What to grow underneath my apple trees?

Jim Fry wrote:What I grow under/around our fruit trees, and everywhere else not barn or pasture, is the best grass that will grow. Then I cut the grass with a mower with bagger. I rotate sections, so I always have high grass ready to cut. Every bit of the grass I mow goes to the various animals we have. For them, it's like candy, -sweet, young, fresh. That way I cut way down on the pasture the animal's graze. Then in late Fall/early Winter, there's good pasture left for the cows etc. By letting the grass grow longer than usual, it helps preserve more soil moisture. And by resting the pasture most of the Summer, it does better.

From observing dozens of orchards or fruit trees around places I've stayed or visited, there's been a pretty clear pattern. Grass/lawn up to the trunk almost always indicates a dying fruit tree. The best look like they are just hanging on and deteriorate over time if it's someplace I return to annually. Fruit trees mulched with wood chips, or better yet 'wild' growth, underneath seem to always look vibrant in comparison.

In this case, I wonder if grazing cows are stirring up the soil and leaving fertilizer 'deposits' to somewhat help the situation? Carrying away the grass in a bagger just doesn't sound like it would be good for the trees.