I have been thinking about the old ways.
Cannot say I have definitive answers, but have made a couple of nonscientific observations.
Less was known about nutrition then, and there were fewer resources for veterinary care, so I suspect many flock keepers were more fatalistic than I tend to be. I want to prevent and treat diseases and injuries. There probably were, though, some number of people who understood plant medicine and had intuitive gifts for caring for animals. Those would be my mentors. But did anyone write anything about what they knew and did?
Many people had backyard animals and knew how to grow and catch food. Animal feed was part of a stream of food obtained by most family members over the age of five, I guess.
Once we set our minds to it, and if we can find others who care and we can work with, I think we can make satisfactory adjustments. But I feel we need to rethink the way we do things and find people who think that way, too. I am thinking for example if a neighbor has a large sunny yard that they are willing to plant to hull-less oats and field peas in exchange for some eggs and fertilizer (and a sense of accomplishment).
Or find someone willing to set up an aquaponics system where fish can be raised. Or learning how to raise black soldier fly larvae or worms.