If mesquite is all the land will grow, fine. Left alone it will ruin and take over good pasture land in just a few years.
Doubt I’d be concerned about it if it took 1000 acres to run 50 head. Hell, anything that grows in those conditions is a plus. But if you can run 100 head on 300, mesquite is not your friend.
50 head to 1000? pure LUXURY!
there is grass too, and some of the best is actually growing right under the mesquites where it benefits from the litter produced by them. a lot of people actually believe the mesquites steal all the water and nutrients and that grass won't grow under them, but if you actually go look that is the place cattle will hit early on. (why "experts" often claim allelopathy, since they didn't see anything growing under there when they went to look for 10 minutes one day of one year, or just read about it)
not saying they can't get too thick or be a huge pain, but a lot of times when they get ploughed up and you see a nice grass response it is more due to ground disturbance than eliminating brush. around here when brush poisoning occurs, it is the several growing season rest that actually produces grass, not the dead brush.