Mine are about 8 weeks old.... what is half grown to you? They are fully feathered and I need to wean them off the heat before I do anything. I was losing them right and left when they were little so I put 2 lights in the pen and now they are down to one..... I need to reduce the bulb watt. It is getting cold here at night... 25 tonight.I move them out to the bantam/growout pen and run (has heat) at about 3-4 weeks when they are feathered out, Let them in the adult side of the pen when they are about half grown. First couple days they act stupid and try to get back in the banty run. but they get the hang of it pretty quick. I have no choice I'll be hatching all winter so I will have heat lamps of some sort out there for all the youngins