One other thing - watch your birds for aggressive pecking behavior, following a victim bird around and pecking around the vent/rear end until she draws blood. Chances are one of your buffs is the leader in this. If she is back at it after you return your cochins to the coop, you'll want to cull her. It's not likely as you've probably caught this early enough, but cannibalism is contagious and brutal. Just keep eyes on.