I have 6 cornish X chicken which are raised with some Ameraucana chicken in the 3'X8' coop. Today I found the cornish feather is so messy. There is so many dirt on their feather. Also they don't have feather on their belly and the part around their vent and under their wings. However, my Ameraucana are very clean and their feather is shinning. So I opened the coop and let them free rang in my backyard. I hope they would get better soon. By the way, my cornish x are 4 weeks old and weight 4 lbs. Are they less weight?