Unless it was grazed in the ground before you got it, maybe not. Is it all this years growth? That's 10 acres per cow, but alot would depend on the amount of snow you get, and how long your winters last. Here we often get a snow of 3-10 inches then it will warm up a week later and most will melt so the animals can go about grazing again. If any snow you get isn't too deep they will nose through it and graze too. We always figure that we can graze 2 places right into January before we start to feed hay and last year they were still doing some grazing in feb. But the grass won't have the greatest feed value by Jan. either whereas hay made right would be more nutritious, then. Do you not have a way to move hay? I would make an arrangement with someone who could deliver it and put out several bales at once. We have 2 small farm customers that we take a couple of round bales to every couple of weeks and just put them right out in the pasture for them in the winter as their small tractor won't handle the big 5x6 bales we make. They are close so not a big problem. They guy sometimes works away for a couple of days at a time so it works for him real well. And one place we take a flatbed trailer of 11 bales and unload them out in the field and they eat the hay and graze too.