It depends on why your horse has rotated coffin bones. Are they rotated due to foundering caused by feed? Or due to laminitis for another reason (drugs, trauma)? If its due to feed founder, then we feed a grass hay, trying to keep alfalfa/protein levels down. If the horse seems to need more to keep the pounds on, then beet pulp is great, as well as flax or rice bran or other added fats, plus a good mineral program.
until one has loved an animal, part of their soul remains unawakened