Chickens that eat their own eggs are a problem for the small-scale free-range egg producer who keeps his chickens in a
chicken coop, rather than in laying cages. It usually starts when eggs accidentally break and chickens discover how good they taste. To prevent your hens from doing this, try to reduce egg breakage in the coop by lining nests with soft nesting material. Also make sure fewer birds share a nest. If the coop is overcrowded there’s more chance of eggs breaking. Four hens per nest is good.
Next, make sure you feed your chickens the right chicken feed. Sometimes eating eggs is a sign there’s something lacking in the birds’ diet. Finally, collect eggs as often as possible. Three times a day is good – in the early morning, afternoon and evening. This will keep eggs fresh and reduce breakage.
Source: poultryone.com