Any grain like rice or wheat should work for the chickens. Goats will eat anything just don’t leave them for a long time in one spot.
Have to be careful with goats, they can bloat with certain things and some plants are poisonous to them (like azaleas) so they can’t eat just anything. Fortunately, well fed goats tend not to eat stuff they shouldn’t though.
Anyway, I’m thinking of fencing off a section of pasture this year and planting field corn, millet, oats, barley, rice and soybean and see what happens.
I have a solar powered portable fence that I can use to move my goats to non fenced areas, plus a neighbor with 6 acres that has already offered to let my goats graze if I fix her fences.