apocalypse scenario in which the entire apocalypse is suddenly every single species of ungulate craves human flesh

which one would be the most frightening? not like individually (the answer to THAT is moose) but as a class. what would be the most dramatic day 1 societal impacts?

i think probably either horses or cows. cows are surely more numerous but i'm not sure how effectively a cow could hunt me

The most immediately problematic are going to be cows/horses, and deer, because both of those live near humans in large numbers.

I live in the middle of some suburb-ass suburbs, surrounded by houses in every direction, and I'm literally looking at a pair of deer right now grazing in my neighbor's back yard. You don't usually see them during hours when normal people are awake, but they have complete freedom to roam in this area. Families of eight members or more, walking up and down the sidewalks, hopping fences between yards, walking the perimeter of every house. If they just decided one day that a sliding-glass door wasn't going to stop them, then there would be no escape.

There are also lots of places were large herds of horses or cattle are in quite close proximity to people. I went to a high school which was across the street from one of those cookie-cutter, hundred-unit housing developments. Perhaps the quarter-mile away was a cow pasture with a dozen cattle. You had to walk through suburbia to get there. At least six houses had their back yard up against that field.

So yeah, Day 1 is pretty high-casualty. After that, transportation infrastructure declines quickly as deer start attacking cars on the highway.