Feeding your flock during cold winters

I feed an all-flock feed, Purina's Flock Raiser, all year to everyone. Separate oyster shell for the laying hens, some garden scraps, a tiny amount of scratch as a treat. The flock free ranges most days, and then winter comes, and there aren't any worms or bugs in the snow, which they hate anyway. Their diet doesn't change, except that the flock eats more Flock Raiser during the winter.
Here we have birds of both sexes, young and old, and this is easy and works very well.
Mary