We have two chicks that are almost 6 wks old. They can now actually jump the side of their pen in the coop so I keep finding them out wandering around with the hens. They seem fine, so is it ok for me to just officially let them out of their pen? Or should I put a top on it to make sure they stay in? If so, at what age are they ok to go out, and go off of chick feed to regular feed?