As temperature / windchill drops below about 50 F, the chickens tend to increase their feed / energy intake. Feed intake can increase between two and three times with birds spending a lot of time outdoors. They have limits as to how much food they can process, so to stay warm they have other mechanisms that kick in. They spend less time in exposed / cold locations, fluff their feathers, and bunch up.
They also start changing their feed selection habits going after food items that pack more energy relative to the volume consumed. Among the options I provide, shell corn and BOSS are increasingly targeted as temperature drops. Care must be taken to make certain nutrient intake is sufficient so I make certain they consume the same amount of nutritionally balanced feed they normally get when temperature is about 50 F. The additional intake is dominated by the lower cost grain mix making up what I call scratch.
Using a flock raiser type formulation greatly reduces the amount of thinking required and will have lot less to manage in your feed storage and processing area. For me it is fun to see the seasonal shifts in preferences that are also influenced by weather events. Over the next couple days with the cold snap, I will be watching closely how the chickens adjust their behaviors and will do my best to accomodate their changing needs.