Any grain that develops should be just as good for the chickens as any you bought. You may not get many kernels though if the corn isn't close together enough to pollinate properly. I had some old decorative corn I found in my seed box from years ago. So I decided to plant it in the flower bed, six hills in two triangles about six feet apart. Only two stalks came up about six feet apart, not really close enough. The ears have only a few kernels on them. With them only four feet and shooting ears (field corn easily reaches six feet plus) I would guess the growing conditions there aren't ideal. Still as a learning experience, since they are this far along, I would let the go.