A chicken's nutrient intake needs aren't so different than ours. They need a certain amount of digestible protein, fats, carbohydrates, vitamins, and minerals - particularly calcium for laying hens. If they are able to free range over good ground during the warm months when plants are growing and insects are to be found a hen can often get nearly everything she needs that way. Nearly everything. What usually comes up short is carbohydrates. But if you are adverse to grains they can get those carbs from other foodstuffs such as white potatoes, sweet potatoes, pumpkins/squashes and so on. With some forethought and planning it can be done. The two big problems lie in how many chickens over how much ground? The more birds the more ground they need to be able to access. And good ground at that. The second problem lies in what to do about the winter time when nothing is growing and there are no insects to be found. Long droughts in the summer can be much the same. Growth and/or egg production is going to slow as the quality of the range decreases to the point they are doing well just to get enough to stay alive. Even that can be met with planning and forethought though. Of course relative to cheap grains and soy proteins those chickens are going to cost more, but it can be done. Could be a good niche market for someone who is interested if they research it carefully and have a market of folks who are willing to pay what such poultry are going to cost. .....Alan.