Please see Egg Shell Calcium.

Too much calcium

Please note that too much calcium is not poisonous, but can damage your kidneys and liver over time. The same holds true moreso for our little animal friends. Your goal is to balance out nutritional needs for the animal, not to dump calcium powder on to everything they eat. Follow the suggestions of the diet you have chosen and also whatever may be current in the community and news. Do your own research on the topic and make your own choices.