My mate's Dad has a place in the woods, and has chickens, amongst other animals. He feeds them a mix of waste human food, egg shells and spent tea bags. Apparently, the egg shells give them back the essential nutrients they need to make more shell, and the caffiene in the tea bags is good for their metabolism. So he said, anyway. There would have been plenty of bugs around for them too.

I do recall those eggs being fucking fantastic though.