My Buff Orpington chicks are 5 1/2 weeks old and fully feathered. We would like to start letting them stay out in the coop at night. Our Barred Rock chicks are 4 1/2 weeks old and mostly feathered but not completely. The Barred Rocks scream uncontrollably if they are separated from the Orpingtons. So my question is, do you think the BR's would be ok in the coop overnight without heat. They have been in the brooder box without heat since Monday with a room temp. of about 73-74 and doing fine with that. The lows here at night outside are in the low to mid. 60's. Don't want to have them get chilled, so playing safe for tonight and brought them in. Here are a few pictures to help.