Bones are safe for dogs as long as the are fed RAW and never cooked. It is the cooking processes that makes bones brittle and splinter into sharp pieces. However dogs can't eat large heavy weight bearing bones of large animals (ie: beef leg leg bones)
For feeding purposes bones that are fed are usually turkey necks, duck necks, poultry frames (the carcass), chicken legs, chicken/duck feet, goat ribs, lamb ribs and necks etc. Some larger bones such as knuckle bones, beef ribs, larger beef neck bones are considered recreational bones. Bones that are chewed on the keep teeth clean and for chewing pleasure but aren't actually chewed and eaten as part of the meal.
Goats milk is a good source of calcium but more for it's probiotic properties. Bone contains both calcium and phosphorous and the two are not interchangeable as for as I know.