The only advice I could give about not getting yb sickness, is not to use darkness.
David, I think you are spot on mate, plenty of easily digestible starchy grains, as these don't make the gizzard work overtime and check any for holding grains. Make a note of any that are, if this goes on for a couple of days, then you have to take immediate action, either starve them right down for a day, or use purging salts. You will spot early signs, usually holding corn and increased water intake.