I think in terms of feeding a limited number of animals on a small homestead, we need to think outside of the silo.

Plus embracing waste not, want not.
Chickens, ducks, and turkeys would have to be free ranged. What you do feed them, feed it after a day outside. So that you fill the empty spaces left not their entire stomach. Hungry birds forage better. Utilize table scraps, and rotting fruit, and moldy foods. They will pick out what they. Allow them to forage your orchard to use the rotting or faulty fruits, not to mention any pests present. Plus any rotting garden produce that the goats or rabbits can't use.
Rabbits could be fed mainly greens except during pregnancy and lactation then you'd have to think of something high protein to feed them. Also tree suckers from fruit trees, they eat the bark. Plus allows them to keep their teeth trimmed down by the wood underneath. Dandelions are also good for rabbits, as well as clover. Maybe some old fruit with the bad cut out. You can sprout grains for them as well.
Goats would be pastured Fall, Summer, and Spring. With some supplemental food, which could be ANY root crop, squash, or extra sweet corn. Plus extra apples or pears from the orchard. The suckers from those trees, weeds from the garden. Maybe even let them in the garden in the fall to clean up. You can feed corn stalks, and I'm sure others things as well.
Something I am considering doing for all of our animals, is to buy the corn and oats in bulk. I feed fermented grains to the chickens and ducks, to my understanding rabbits can be fed oats with hay supplementation plus greens, then goats and cattle can be fed fermented grains as well. So I am going to be adding grain bins to our shed.