It’s not that we’re necessarily getting more snow than we’re used to, but that it’s laying longer; the result is that more thought must go into each day’s decisions about grass and grazing.
Not only must we consider the condition of the standing grass (‘stockpiled forage’) and the depth of snow on top of it; the quality of the snow itself, over and above quantity, comes into play. What kind of snow is it? — and how long has it been here? turn out to be significant questions as well.
Any amount of powder snow may be brushed aside with a cow’s muzzle (while horses and sheep scrape through the snow with their hooves, cows — ours, at least — push it with their noses), but any more than a thin coat of ice on top of the snow will make for reluctant grazing. Nevertheless, if that’s what’s for dinner you can serve it, and hungry cows will, if they’re clear that you aren’t going to give in and fetch a few bales, get their noses down and have at it. Wherever their feet have already broken the crust they’ll begin foraging, and move out from that spot to graze more widely. Thicker ice is a real barrier to grazing — even walking, if the ice is thick enough; a skim of ice on top of snow will cut a cow’s shins, not dangerously, but enough to make them unhappy. They’ll huddle together, trampling a perimeter beyond which they will be reluctant to go.
Slush is yet another matter. If it’s not too thick — half an inch seems to be about the limit — our cows will be philosophical about eating iced forage; beyond that the trouble may not be worth the reward. But slush has another effect on winter foraging, since it packs down wherever it is stepped on and traps the grass underneath, then freezes. When the snow melts this grass will be pressed down to the soil, where it’s hardly accessible to bovine tongues and will in any case rot quickly, adding to the soil carbon but no longer available as forage. So slushy paddocks have to be calculated to allow a percentage, and not a small one, for waste; which allowance has repercussions in the form of potential shortage down the season.