I have 26 week old chicks in a large plastic bin. I change their padding (layer of oak sawdust, layer of newspaper, covered with paper towels) twice a day. I just went to change it and I noticed several of the chicks have matted feathers on their bellies. I checked all their vents, no problems there. Do I need to worry about their bellies being dirty? I know they need to be clean, but I don't know what else to do to ensure they keep out of the poop, and boy are they pooping a lot.