I feed an organic, whole grain corn and soy free feed. They use fish meal for the main protein instead of the soy which I feel is better (and so does Lions Grip) and it has a good amount of Omega 3. Its a bit of a pain as its a mash so for them to get all the powdery vitamins and minerals in the mix I give them their breakfast slightly moist and they can't pick out only the grains.
I do give BOSS (Black Oil Sunflower Seed) a few times a week as a treat!
Depending on where you are there are many companies offering soy free feed & some have corn free also. In PA we have one company that I know of offering soy free. Locally I can get soy free from an Amish farmer who is a dealer for Fertrell products. You have to ask around in your area. I know soy free is available in Ohio, Texas, Virginia & California, to name a few.