Yes they don't have both. I have a shed that I move from paddock to paddock with the tractor. I have been using movable electric net fencing. I built a paddock with pasture fence last weekend to get ready for winter.
It depends on the type of grass, what is in your pasture? Usually toxins dissipate after a week or so, but not always. If they were mine, and the grass was ok, I would toss out a protein tub or two and let them eat it as long as possible.