Actually, GMO is NOT perfectly safe to eat. It messes with hormones because of it's very nature of being manipulated by humans to grow faster, taller, stronger, more disease resistant, and with more kernels. Hybrid corn, which is nature way of modifying it, is ok. Too many people think GMO is good but look at us Americans ... we're huge and corn is a really big part of our diet. It's almost impossible to get non-GMO corn seeds anywhere, and I look because I grow them.
I stopped giving my chickens corn only a short time ago, and already their egg production is up. That's the only change I did. So ... no more corn for my girls. They really enjoy amaranth, quinoa, millet and flax seeds. For some reason, they don't like BOSS. And if they need help keeping warm in the winter (like here in Colorado), ground up alfalfa helps there.
Just my 2 cents.
Baker creek seeds carries a bunch of Heirloom non gmo corn varieties. I grow a giant indian type corn that grows huge ears and most have at least 3 ears to the stalk. I also started with the millet,sorghum,amaranth and sunflower from their seeds. Basically everything we grow is from their seeds and can see the difference in the hardiness and the taste of the Heirloom varieties.