My dad is 83 and I asked him this question as his parents always had chickens. He said they only kept enough over the winter to lay enough eggs for the family and his mom would go out twice a day with fresh thawed water for the hens. Sometimes three times a day depending on how cold it was. They would cull 1/2 of their flock right before winter for food every year about the same time. Then right before spring they would allow a few hens to hatch out a bunch and start all over again. They would then cull the hens that lived through that current winter for the next winters food by that time the new hens would be laying eggs already.
But what did he feed the ones he kept over winter?
But what did he feed the ones he kept over winter?