The temps in their room is 79 and I have a light bulb on my 3day old guineas and peababies and will (weekly raising it) until they are feathered.They spend a lot of time under the light and I lost my first keet ever (15 years) when it got away from the light and got too cold. I add a couple of teaspoons of acv to their quart of water until their out of the brooder and feed 28% gamebird feed. . Works for me.
When they look or act frail, I assume they aren't keeping warm enough unless its obvious that isn't the problem.