Feeding protein is a catch 22. With protein they tend to hammer only top preferred plants/forbes, with out they tend to graze equally

That really depends on the ranch also. I have seen it go the opposite direction with plant selection on protein and when/if they eat those plants.

You guys have fed protein on a much larger scale than I have, but I know when I used to give High protein to my cows, either syrup or cube, they'd eat barbed wire dam near (if the protein was high enough) basically would eat any native grass they could, to cure the "burn". Plus the added intake of water.

I just assume deer would be similar, but maybe less so, since their stomach system is less than.