3 of my 11 hens are a little over a year old, and went through their first molt this fall. I noticed last night that those girls are now much lighter, and less musculatured than the other hens right now. They have all their feathers back now, so I didn't notice until I picked them up. Is this normal? I saw some posts talking about worms or parasites, but their behavior is fine, and all my other girls are great. I don't want to medicate unless I have to. Suggestions?