We decided to put my 25 pullets who are 11 weeks old today in the pen with my 4 six-month old hens. The roos have been in with the hens because the hens were young enough that there was no fighting amongst the roos....till last week. My hens have bald heads so it was time for the roos to have a bachelor pad till the 25 other pullets are old enough to keep 3 roos happy. We had to basically herd the pullets in and the roos out at the same time. The roos attacked the pullets mid0run between the pens! I had to get in there with my boots and gloves to keep the poor babies alive! The hens didnt even look twice at the pullets... I stayed to watch the introductions to be sure there was no immediate fighting, and the hens just went to scratching and eating side by side with the babies. we checked them again later and all was still peacefull, but the displaced roos are ticked! They will adjust, it wont kill them. I was shocked to see that agression coming from my shy roos!