I don't see why they wouldn't be "digestible." In home-cooked diets, people often cook a whole chicken or turkey or whatever until the bones are soft and feed everything. I do this in the winter with rabbit - sort of a rabbit stew
Never had any problem with it.
ADCH Mikko (USDAA) SCH-B; (NADAC) EAC, EJC, TN-E, TG-E, VerO; (AKC) NAJ, CGC; (NACSW) NW1 - 9 year old GSD