If many of my perennials have been sampled by the big horn sheep, will they(plants) likely come back in the spring? Do sheep eat things that deer do not?

For the most part perennials will come back after being chewed down. Many of them are herbaceous, which means that they normally will die down in winter, and come back from the roots. I haven't seen any literature on the tastebuds of sheep versus deer. I suspect that they are quite similar-a list of plants that deer don't like would probably include many of the same plants that sheep wouldn't fancy either. Both will try almost anything though!