I'm not sure if this is exactly what as meant by a 'Winter Mash' but there are a few mash recipes included in the 200 Eggs Chicken Care Guide (used by various poultry farmers of 'the old days'). It also includes details on food values and what a chicken needs so you can devise your own aswell. Here's one winter time mash recipe for laying hens that may help :
"From October to May I feed as follows: A mash the first thing in the morning. The mash is made as I am about to describe. Into an iron kettle holding 12 quarts I put two quarts (dry measure) cut clover, two quarts mixed feed or wheat bran, two quarts corn meal, one quart green ground bone or beef scraps, and one quart table scraps. The ingredients are thoroughly mixed together. I then take the kettle into the house and set it on the range where the metal can become warm. I next stir in a heaping teaspoonful of coarse-fine salt, and in the coldest weather sprinkle in a little black pepper. Boiling water is then added to the mash in just sufficient quantity to moisten every particle and yet not have it sticky and sloppy. I consider the mash just right to feed when I can take some up in my hand and have it feel pleasantly warm (not hot), and dry enough so that it will not adhere to the palm or fingers. Some advocate dry feeding. I have no doubt the food is just as nourishing without the water, and after they become accustomed to it (or starved into it) the hens will eat it readily enough; but before the food can be digested it must be moistened, and I think it better and safer to moisten it for the birds myself than to allow them to do so. I do not believe the bird can moisten a large handful of dry mixture after it enters the crop so evenly as I can before it goes there. Then if the mash is about the temperature of the bird's body when it is fed (or, on cold mornings, a little higher) she will not have to use up her heat in raising it to that temperature."
Photo : lanuiop