I have been giving my girls warm oatmeal on these cold mornings, and they love it. I heat it up (I cook up a big batch ahead of time), add hot water and their regular chicken food (I use Scratch and Peck layer) until it's a good consistency, and top with warm grapes cut up and a few mealworms. Yum!
As others have suggested, oatmeal is a great treat. I ferment my feed and on cold mornings I will zap it in the microwave for a minute or so. They absolutely love that.
Just adding hot water to their regular ration to make a warm mash will work.
People also suggest a handful of cracked corn tossed to them in the evening prior to roosting will help them generate extra body heat during the night as they digest the starch in the corn.
I, too add warm water to their regular feed for another warm treat later in the day. I haven't tried fermenting yet. The feed I use has lots of "fines" in it with a majority of the vitamins and minerals, so I feel this makes it easier for them to get a more complete package of nutrients. I have added some scratch with corn since cold weather has hit. I still can't believe they prefer being outside all day when the weather has been so windy, cold, and rainy. I'm glad they have a roof over their run and that their coop is in a protected spot! (This is my first winter with chickens)
Oatmeal, warmed up with ‘whatever’..... sometimes raisins or berries, chopped fruit or veggies. Sometimes just plain. Scrambled eggs. They seem to like my butternut squash soup too make a warm mash out of chicken their feed. Warmed up chopped veggies. Cooked polenta, grits, quinoa are always popular. Mine always have a flock block to keep them busy during winter days where they choose not to leave the coop/run