De-worming is a start. Provide them with plenty of free-choice hay (roughage) as well as decent pasture if you have it. Might also include a flake of alfalfa hay along with hay choice. Range cubes and/or some "beef feed" of the bagged type can also be used. Be sure to provide them with free-choice mineral block (or molasses tub) plus other salt (if minerals have low salt content)--these are needed for health and nutrition as well as stimulating them to eat more roughage and drink more fresh, clean water. Good luck! P.S. it may take several weeks or even a few months to get them back into good condition.