I know this was posted months ago and I haven't even come close to the 625th page yet, but..... do chickens process seeds thru their gut like cows do? Is it broken up and truely digested or will it still pass whole in their stools? I'd be fearful of the thistle seeds that are so prevalent in the wild bird seed feed. I've been extra cautious about not throwing out to my hens the blackberry pulp (w/ seeds) just because it's such an invasive weed here in PNW.
Most larger seeds will be ground by the gizzard but I've seen smaller seeds such as flax seen come out in the stool. Smaller, harder seeds could indeed escape grinding and digestion and be expelled to live another day.