Here at Polyface, our grass goes dormant in October. We still have a lot of it on the ground at that time, so we continue to graze the cows on pasture, moving them daily, on into the winter until they finish eating the stockpiled forage, then we feed hay. This year we did not start feeding hay until mid-January. It's perfectly fine to feed hay to the cows on the pasture in the winter, but you lose a large part of the nitrogen, phosphorus and potassium (the fertilizer) out of their urine and manu