Not recognizing it as food might well be true, or maybe they just don't care for it. We planted a plot of brassicas/turnips last year. The deer didn't touch it - ever. And it was a very nice plot, good leaves, big turnips. I've heard brassicas get sweet after it freezes, so maybe it's still too early in your area.
“There are two spiritual dangers in not owning a farm. One is the danger of supposing that breakfast comes from the grocery, and the other that heat comes from the furnace.”