Several hundred years ago when farm labor was all by hand and no tractors, farmers would use their animals to prepare a new field. Cows first to take down high grass, goats to take out brush and foliage, sheep to mow grass short and finally hogs. The hogs would root up the stumps and toots leaving the ground turned over and easier to get the plows into. Not a quick process - at least a year - but it beat doing it all by hand!