Some inexperienced young pairs may destroy their eggs or chicks. If a squabble has taken place in the nestbox and an egg has broken, the hen may eat the broken egg in an attempt to keep the nestbox clean. If the eggs are being deliberately destroyed, replace the newly laid egg with a plastic egg. Once the birds realize the eggs can't be destroyed, the problem is usually solved. It is not uncommon for this to occur to young, inexperienced pairs. Often the problem will resolve itself and the next clutch will go smoothly. If a pair continues to break their eggs, try to detect which bird is causing the problem. At this point you have no choice but to remove the guilty bird from your breeding program and replace it with a new bird. I have never known of a confirmed egg eater being reformed.