You Could use a All Grain Pigeon Feed, it a all kinds of grains in it. Most have at least 14% protein and I have seen it all the way to 21% protein.
Also you can get Pigeon feed with or without Corn and most if not all don't have Soy in them.
INGREDIENTS -
Popcorn, Whole Milo, Canadian Peas, Whole Wheat, Maple Peas, Austrian Peas, Oat Groats
INGREDIENTS -
Canadian Peas, Austrian Peas, Wheat, Oat Groats, Milo, Red Proso Millet, Maple
If you cant get a all grain pigeon feed at you mill you can try -
Cracked corn - 31%, Wheat - 17%, Red Wheat - 16% Yellow/Green peas - 16%, Barley - 7%, White Wheat - 6%, Buck Wheat - 5%, Safflower Seed - 2%
( Above mix should be 12% Protein - 3.1 Fat ) also note that % is by weight, so 17% would be 17 lbs
Chris