The "Perfect Winter Stockpile" for St Croix Sheep?

https://www.purenaturalsheep.com/ What is the best winter feed or stockpile for St Croix Sheep? St Croix sheep are best at being grass fed, so feeding grain through the winter is not the correct action. Should you grow tall grass in the summer for a "winter stockpile", or bale the grass and feed as hay bales? This video asks some pretty obvious questions about the entire concept of a "winter stockpile" consisting of grass that is never cut or open to the sheep to eat, but is left out to waste away in the cold snow of the winter. It makes a lot more sense to bale your grass into hay bales than to leave it out on the ground in some sort of "winter stockpile." Thanks, John Hurt