I don't give our dog raw bones at all. There is the mess involved, and I don't want the risk of a splinter passing thru the digestive tract. The raw pre-mix that we use has some ground bone. I add a little bit of finely ground egg shell (cleaned & baked to sterilize) once or twice a week for calcium. Human grade calcium carbonate or citrate can be added at a rate of 900mg per lb. of raw food, too. That's all I know, but seems sufficient. The dogs do need their calcium, just like humans do.

Actually, I gave Sophie a beef short rib (don't know if you have these in the UK and Ireland) and she looked at it as if it were a foreign object. She kept looking at me, as if to say, "what do I do with THIS?" I finally picked it up and never tried it again.