I'm definitely not an expert, but we have winter wheat down at our farm and they seem to use it a fair amount late in the season...like late December and January. That's the first time they've planted that for quite a while, but I was consistently seeing about 25 deer per day in this 16 acre field in the afternoons.
I'm sure it's good for the deer, otherwise they wouldn't eat it. They have a sense for eating what they need, especially during the winter months. I've heard many more good things about alfalfa than winter wheat though, so it doesn't surprise me to hear they're in that a little more.
Hopefully that clears it up a little :-)
Take care,
Ryan