The calcium citrate with D is available or the brand name Caltrate and contains 300 mg, fine for a bantam or large hen. The large hen can have 1 or 2 of those. That is the most accurate dosing, and giving 1 orally daily for 7 days is a good way to see if the calcium will help or not. The D is good to use with the calcium because the calcium is absorbed better. The danger of the shell-less eggs is they can get stuck because they are more difficult to lay, and if they break, it may lead to infection or eventually coelomitis/egg yolk peritonitis. If she is starting to molt, she may be getting ready to stop laying after an egg or two. Can you post any pictures of the areas she is losing feathers. Mine always seem to drop tail feathers and start molting on their necks.
