This is a post I made from earlier.
Ripshod said:
and the calcium in cuttlefish bone is not bioavailable for birds.
Like Ripshod says the calcium in cuttlebone is not bioavailable to birds. The most available calcium is calcium carbonate and it can be bought very inexpensively.
Calcium carbonate is the mineral found in wild
bird foods.
Calcium carbonate is quickly and efficiently broken down in the digestive tract to be easily absorbed and used by the
bird.
Why wild birds need foods with calcium
Calcium is the most challenging mineral that birds need because of the extreme changes in periods of demand (like egg laying and chick development) and because many foods are likely
billingsgazette.com
Cuttlefish bone is often sold in pet stores as a calcium source for birds,
but the calcium it contains is not easily absorbed by birds. It makes a good chewing/shredding toy for the birds, but that's about it. If your bird only has a cuttlefish bone in their cage for the calcium, it is important that you supplement with other calcium sources, such as boiled eggshells and a more effective calcium and vitamin D3 supplement
http://www.tailfeathersnetwork.com/b.../nutrition.php