I put some in with the rest of my flock at 3 1/2 weeks, the broody raised chicks were only 5 weeks and she had abandoned them at 4 weeks. They mixed right in to the flock as if they had always been there. I think the rest of my chickens were afraid that if they messed with the younger chicks that the ninja broody would come get them.What is the earliest age you have put chicks in with hens, assuming there was no broody involved?
I usually wait until the chicks are almost as big as the hens, but this batch seems to be doing so well with the hens. I've been feeding hens and chicks treats side by side, separated by a mesh fence. The hens have been able to check out the chicks at eye level for about 3 weeks, and I've had two escapees who have been unharmed by the hens - I know the hens saw the little chicks being free - alhough I just scooped the chicks up and returned them to their enclosure. The hens have access to three sides of the outdoor enclosure and seem to have lost their curiosity about the chicks.
Now, the chicks are 5-6 weeks old.