As long as you're rotating you may be surprised. It's good to keep them off their regular pasture for a week to let the grass get a chance to bounce back. If there's one species that can destroy pasture by overgrazing, it would be horses.
The goats would be good to help keep weeds down to...if they'll stay home. Big emphasis on "if" 😉
RE: Rotational Grazing VS. Mowing? - Homesteading Chores