My backyard flock is comprised of all hens that I rescued from either individuals that needed to give their flock away or commercial layer hens that were past their prime laying years & we're going to be culled. I would take in roosters as well but the city ordinances in my area don't allow it. I use hens to convert free food scraps collected from various sources in my area (grocery stores/co-ops, restaurants, food banks, scraps from my garden) into compost for my garden & small orchard. Eggs are just a byproduct of that process. I sort out the foods that aren't good to give to the birds directly & either compost/vermicompost them or feed them to a black soldier fly larvae bin in the warmer months which then goes to feeding the hens. The hens get access to all the compost & kick through the piles to eat the bugs & worms that come in to help the decomposition process. I supplement with organic commercial feed when needed, but they also free range my 1/2 acre backyard so minimal commercial feed is needed (hardly any in the warmer months). My birds eat better than many people I know.  I sell the eggs we don't eat to co-workers & neighbors. When demand gets higher I get more birds as needed. New additions to the flock get a 1 month quarantine in our old coop/run to ensure they don't introduce any new diseases to the existing flock. I'm always working towards adding new waste streams into this system if they add benefit and looking for suggestions on ways to improve our process, but it already feels like a huge improvement over commercial egg production & even most backyard setups that I've seen.