I put up a video on youtube yesterday on our chicken system.. https://www.youtube.com/watch?v=0FFzf5i8aw4 . I am documenting our first year having chickens with a system somewhat inspired by the Vermont Composting Company. They use chickens in their large compost operation as co-creators of the compost. The chickens have full access to massive piles of unfinished compost, and they live off it, entirely. They get an incredible quality of life, basically kicking apart an unlimited pile of a continuum of decomposition, get warmth from it, and in exchange help to create a finely textured finished compost. We're exploring it on a much smaller scale with our 25 chickens.
In the winter, it is a challenge to try to feed our chickens for free, but we've been able to do it almost entirely (a little kelp here, some oatmeal there, some grit, but almost entirely compost). By building a large compost pile in the fall and tending it through the winter, we've been able to make a hot compost that has been a reliable source of warmth and food for the chickens through the coldest times.
The tarp lets me cover sections of the compost to help build up heat when it's super cold. The chickens get a little 'window' to kick around in, then I can move the tarp to give them access to sections that have built up more heat. Logs on string at the corners keep it in place on the windiest days. Super low tech.
By adding about 5 gallons of seed each week to the compost, they get basically an unlimited amount of sprouted grain all winter. The seeds/flour comes from my good friends at Farmer Ground Flour. They have machines cleaning the seed coming in and have bins for this and floor sweepings (that goes through a huge magnet so no metal is left over). I barter for it, and this addition to the compost makes for a real powerhouse food source. The chickens can choose raw hard seeds when they want (I don't turn them in, it gets scattered on top and they 'plant' them), or can eat sprouts when I pile the compost.
It feels like a pretty amazing system for the chickens to be able to scratch and dig straight through the winter, getting quality exercise, being out in the fresh air and cold bright goodness of winter, but on a warm place with massive piles of sprouts to eat all day. I come out once a day or every other day and use a hay fork to build up new piles and they kick 'em apart.
Last week I was able to harvest 6 wheelbarrows of un-finished/hot compost to add to a new greenhouse I'm building and there is still a mountain of compost for the chickens. By adding in a truckload or 3 of wood chips in the fall, along with 40+ bags of leaves that people put out on the curb in the fall, then a continual sprinkling of grains and food scraps, this pile has provided super high quality food, activity, warmth and a high quality of life for our chickens. Not to mention the quality of the eggs!