I found a feed mill that has GMO free feed. I have tried ground feed in the past and the chickens appeared to waste a lot of it. How do other people feed ground food like this so there is less waste?
Short answer, you dont, Chickens are always going to leave something behind, even if you throw out a handful of corn they still leave a little behind. It is best to just feed them in a feeder, or accept that they will waste some.
I feed "mash" or ground feed from the mill. First, a dish feeder, like those rubber bowls works well. I take a 2 quart scoop of mash in a feed bucket and dampen it with warm water. Stir and leave sit for 5 minutes. The mash becomes like oatmeal or porridge and I stir bit more before feeding. There is very little waste if you don't over feed more than they can eat in a reasonable period of time. The mash becomes more like crumbles in appearance. If there is left over gravy, or juice from the crock pot or similar? 'Tis a grand thing for the birds. The quality of the fresh ground feed is motivation for me. The price is 40% less than pre-bagged, trucked in feed. Another motivation. So fussing a bit with making the mash is not bother for me, as I am retired. It is what fanciers fed their birds for decades before pelletizers were invented. May not be everyone's cup of tea.
We use the rubber bowls or a feeder in a double bowl system. I put the feeder in a rubber bowl that is a slightly larger diameter than the feeder and empty the feed they scratched out back into the feeder as necessary. Or use a rubber bowl that leaves about two inches between the two bowls all the way around, the feed that they scratch out is poured back into the center bowl. I had no idea how much feed I was losing until I did this. I am using about 50% less feed than I used to. Good luck