Best practice would be feeding couple pounds of grain on pasture. I subscribe to DR Kennedy logic on this. If you have to much pasture, you either hay it or need more ewes. Mine don't see pasture until after second lamb crop. They get mixes with mature ewes at 2nd breeding season. Kept in thier own gruop from 100 pounds until then.
Right bow. Pen of ewe lambs. Pen of yearling ewes . And Tue rest. All mature ewes on grass. Well when I got home from watching a lamb show and picking up supplies for trip to Sedalia,75 mature ewes were grazing in my neighbors corn field. Which is technically a grass feild.