http://www.sustainablechicken.com/"breed selection will be important: choose chicken breeds that are good foragers, more wild and hardy, able to walk around and feed themselves from the land.
deep bedding within the hen house and in an enclosed outdoor area can develop into a rich, deep compost over time that will provide many small bugs and insects that the chickens will be able to scratch and peck into for a substantial amount of their protein needs. There are many forms this strategy could take.
compost can be used in multiple ways by poultry for supplemental feed, and to turn the compost for the gardener, saving some labor and chiropractor bills.
planned grazing around a property allows chickens to access a variety of food sources, spread their manure around, and give them and you the pleasure of each others company. Obviously chickens love to roam the garden, scratching and pecking on a daily rotation around a property, finding bugs and soil critters, and eating the plants and herbs they like to keep them healthy. Planned grazing implies that you are pulsing the chickens out into a section of the property in a deliberate manner, in order to minimize any overgrazing or damage to the plants within that property section, limiting any buildup of manure and possible pathogens, and minimizing the damage to soil roots and mulches (from dust baths for example). Planned grazing also implies that you are making sure there is adequate food within the property section for the chickens to eat. If it is mostly bare ground, there won’t be much for the chickens to eat.
Joel Salatin claims chickens can get 20% of their daily calories from grass (You Can Farm, page 233). I assume this is calories from carbohydrates (seeds) and protein from bugs and lots of minerals and vitamins from fresh grass and herbs. Carla Emery confirms this saying chickens “will use greens for 20% of their diet” (page 652)
chicken food forest is a mixed planting of multiple plant species that chickens are known to prefer. A food forest generally consists of a mix of trees, shrubs, perennials, grasses and herbs. There are many species that can fit the requirements for a useful food forest, and special attention should be given for mixed use species, plants that provide food for humans as well as chickens, might be placed to screen an unsightly view, or might provide shade.
duckweed could be the cornerstone of a sustainable poultry farm. Research indicates that duckweed is not difficult to grow, and is one of the richest sources of protein. As you might infer from the name, it is a weed that poultry like. The richer the brew it grows in, the higher the protein and the higher the quality of feed produced.
home food scraps are a well known and well used strategy. There are ways to improve the palatability and usability of the food scraps, that will increase the quantity that the chickens eventually eat.
worms and vermiculture is another well used strategy. High in protein and easy to grow, wrigglers can be an important food source for chickens, and oh how they love to eat them.
gleaning is collecting unused food resources that would otherwise go to waste. One of my favorites in Santa Fe was grabbing the large bag of popcorn leftover from the movie theater at the end of the night.
OK, that’s probably the major strategies, let us know if you have other ideas."