I came across a similar post earlier. Question - Do you feed your chickens egg shells? It is a common practice and is good for them and the strength of the eggs that they lay; but a common mistake is that people wont grind then up first, just throw whole, cracked, shells in with their feed. This is a quick way to teach them that their eggs are a source of food. As far as training them out of the habit....??? I will follow to see if anyone has a tip! A squirt bottle like with cats? HAHA Good luck friend!