I thought I'd dig this thread back up.

I found something really cool at the local feed store. Solid gold makes a supplement called steamed bone meal (it's made from beef bones). It is in powder form and 1 teaspoon adds 1368mg calcium and 684 mg phosphorus.
Steamed Bonemeal at the Solid Gold website
The calcium issue is all that has been holding me back from making my own, so I'm looking forward to trying this. I picked up some whole chickens and some brown rice today, so I can't wait.
Misty