General feed for rural ferals

I hope I'm not repeating a previous thread. Most of the recommendations for feral pigeons refer to urban areas. I recently moved to a farm that my grandparents had lived on. My grandfather had retrofitted a section of the barn into a loft for feral pigeons that I would like to begin using again.

We live in a very rural agricultural area - less than 2 homes per square mile in north central Minnesota and orphans that we've raised all seem to be very healthy. I haven't found any with lice or had any problems with sickness. Stray cats are a huge problem though and by using the loft again, I'd like to encourage the friendly "yard ornaments" and help discourage the cats that find young squab easy pray.

We have locally raised grain available of many types. If I'm purchasing feed, what would be good types of seeds to offer? I know millet is espcially popular with doves. I do realize that these are just "rock doves" that will eat almost anything, but as long as I'm feeding them, I'd like to do it right.

Thanks!