I have 20 week and a half chicks. The two biggest ones will start panting when they're all sleeping carpet style (all together but not on top of each other), but they don't move over to the cooler side of the brooder. I have a series of boxes connected with doors that is about 5 feet long (man are they entertained by running around through the doors) on one side the brooder fluctuates between 85-90, on the other side its 75-80. Should I worry about the big ones who pant? Also, I've been leaving food for them to feed freewill, is there a certain age where I should take away the food for part of the day?