Based loosely on:
We had a 16 lb turkey carcass and we made stock the day before (yielded 6 quarts).
Used 1 cup barley, simmered covered for a half hour. Added 6 sliced carrots and 5 or so sliced celery stalks, along with whatever shredded turkey. Simmered for another half hour or so until veggies were tender. Turned out pretty well.