I would not give her too many calcium tablets, especially if they are human calcium plus vitamin D tablets like Caltrate. Too much calcium can be fatal. Calcium is an electrolyte and muscles and nerves including the heart function on electrical currents based on a balance of electrolytes in the body. Their heart can go into a lethal arrythmia and stop with too much calcium. As with any animal, and even people. They know how much they need and eat calcium when they need it, so free-choice oyster shell and a good quality layer pellet in their daily ration is sufficient, as well as access to grass and vegetation in the warmer months.