I heard Paul Greive say this recently, and it really stuck with me because its so simple—and we get it wrong so often: "animals are meant to move".
When animals are stationary, their food has to be brought in and their excrement has to be brought out.
While convenient for keeping tabs on them, this system of raising animals is really quite contrary to the way animals move, feed, and fertilize their way across the landscape.
In the wild, plants feed animals and animals feed plants... but only when they are free to roam.
Again, so simple but so central to the way the natural world works.