It'll depend on your stock and how much forage is left under the snow. My cattle won't lose an ounce of condition with only a couple inches of snow on the ground. I don't get all that worried until I see 6 inches on the ground. But my animals are used to having to get at their feed, and are specifically selected over the past few years for easy keeping.
If your animals aren't used to having to root out feed, or they're hard doers, you may need to stick some feed out. I'd give it a few days and see how they're making out. You'll know in 2 or 3 days if your stock will adapt.
Rod