My approach requires you observe and think so you need to be on your game.
To control feed costs, I provide my birds a fixed ration as a balanced formulated feed that approximates a flock raiser in terms of proximate composition and energy content. When the weather is warm (> 50 degrees F), that ration is effectively free-choice access to the feed. As temperatures drop, they have interest in eating more feed. Being homeotherms / warm-blooded, the chickens must make adjustments to maintain body temperature against the the cold. Part of that adjustment is through increased feed intake. They do not need additional protein or other ingredients for growth, rather they need energy (calories). This is where the potential for cost saving comes in. I use a grain mix (approximates a high end scratch mix minus cracked grains) to meet the increased feed intake birds want. When the grain mix is used later in the day, all of the complete ration has been eaten before I check pens. This is often near dark, and when snow is on ground can be after dark. If birds need energy, then they will even come down from roost to eat. The larger intact grains are easier to see and ingest under low light levels. They quickly top off crops and get up on to roost. I could do similar using more of the complete diet formulation although it is more costly, mostly because of the protein the birds do not need more of.
I am a animal nutritionist (scientist type) that is fascinated by the behavior of the birds and how it changes as a function of feed type and environmental conditions. I have been doing this for quite a while and was trained by parties that kept chickens in a similar manner for a long time before I was born. My teachers did not have the formal training of a scientist ,but they knew their stuff none-the-less. My birds are flat out sexy and are expected to live longer than production birds so approach is at least good enough for that.
What remains to be seen is how much energy is consumed when what is offered is the complete formulation versus the grain mix (incomplete formulation). My suspicion is the birds consume more of the intact grains under the conditions I provide in the time allotted.
Most of my birds will be sleeping under stars through next April. Energy intake will at least double during periods of extreme cold, especially when there is wind. Thermal stress they experience is much greater than what those in the barn experience, yet the barn birds step up their intake as well. The barn birds have an easier time staying in lay when it gets really cold. In the past when I kept birds in a proper chicken house and could see a similar pattern although changes in feed intake were not as pronounced.
