There are many farming systems in the world, aimed at putting chicken and eggs on people's plates. The most abhorrent chicken keeping system, battery cages, is not usually used for meat birds: this system is usually reserved for egg production (and the quality of that egg???).
Most commercial meat birds are grown in a barn, or a series of barns, with artificial feed, and very little access to outside. More and more egg farms are run this way now as well.
As Permaculturalists, we should be trying to allow chickens to fully express their chicken-ness.
"Free range" is almost getting there. These birds are kept outside, or allowed access (or the possibility of access) to actual ground to scratch, even if, in the worst cases, that ground is compacted bare dirt. Popular with consumers, this might be considered to be a marketing tool as much as an actual farm practice.
At the moment, I believe the pastured hens to be the best (current) practice for commercially raised chickens and eggs. Some excellent examples of these are of course Ben Falloons Taranaki farm, and Joel Salatin's Pollyface farm. In these systems, the chickens are part of a multi animal system, where they follow after cows in a rotational grazing system which improves the soil for very few external inputs.
What are pastured chickens eating? Grass. Insects found in a grass ecosystem. Seeds (largely from grass, but also from weeds). Supplemental feed. Joel Salatin reminds us, these are productive chickens. If he wants to make a sufficient income to keep the birds, they need to produce a large number of eggs, so supplemental feeding is essential.
Geoff Lawton has a system with confined chickens ( http://www.geofflawton.com/fe/64322-chicken-tractor-on-steroids ) based on another system he visited with "free to leave" chickens ( http://www.geofflawton.com/fe/59960-feed-chickens-without-grain ) which both rely on the chickens being fed on food scraps, clean garden waste, crop remnants, and so on, which they turn over, peck over, break down, and add manure to, making excellent compost. These birds may have a more diverse diet than pastured birds, but their food (albeit wastes from other systems: a good Permaculture use) has to be brought in, and it is predominantly fruit and vegetable matter (which is fine for chickens: they are omnivores) which means they are missing out on the seeds, and the small animals they would be getting in large(r) numbers on pasture or range.
Good systems as far as many Permaculture principles go: each animal is muli-functional (producing eggs, manuring the pasture, eating bugs etc.) There is virtually no waste as compared to a barn system, where the manure needs to be cleaned out and taken away. It works with nature by not attempting to restrict the chickens' self expression. BUT. . .
The domestic hen, gallus domesticus is descended from (or considered a subspecies of) gallus gallus.
The common name for g.g. is Jungle Fowl (Red Jungle Fowl or Grey Jungle Fowl, two closely related birds). Yes, Jungle Fowl. JUNGLE fowl. Now: take a quick look at a jungle, and tell me how much pasture you see. What you WILL see in a jungle, that you won't see in pasture, is a vast array of plants, including fruiting plants and leafy green plants and possibly some grasses. You will see leaf litter, sometimes feet deep, on the jungle floor. Among that leaf litter there will be a greater diversity of insects than you will find in pasture. Plus gastropods and annelids. Plus small reptiles and rodents. Chickens are omnivores. oh BOY are they omnivores. The most offended I have ever seen a cat look, she was playing with a mouse, in that way that cats do: catch, release, catch, release. . .until, on one release, the mouse made a run for it, right between the legs of a chicken. Whereupon, the chicken pecked at the mouse once, and swallowed it whole. You may have heard that "goats will eat anything". . . they have got NOTHING on a chicken.
So, are pastured eggs that great? I think they are better than ANYTHING currently available commercially. I think their diet is diverse, and their lives are probably low stress and they get to express their "chicken-ness"
BUT I think "Jungle eggs" would provide the pinnacle of egg quality, and chicken quality of life. Bring on the chicken integrated food forests!
