Built-in brooders are a great idea! My coop has two sides to it - the main 8x8 section and a smaller 4x8 section that I use to store feed, etc (we call it the "people side"). We put down shavings in our "people side", and used that as a kind of "transitional brooder" for the new Barred Rock. We installed a block on the door between the two sections so that we could lock it open just wide enough for the little ones to get through but not the big girls. We keep the little ones' water and food (they are still on Start & Grow) on that side. The little ones haven't shown a bit of interest in the layer pellets, though they are certainly acessible to them since they can come and go as they please through the whole coop now and seem to spend most of their time over in the larger side and in the run. Might be the texture - I guess they prefer the crumbles that they are accustomed to. Also, since they free range in the afternoon, they get plenty of variety in their diet and maybe the layer pellets just aren't all that interesting.