I've planted a few small plots, and the biggest gains that I've noticed is with the use of phosphorous fertilizer. Plants grow like crazy, and the animals prefer the plantings that have been fertilized with the phosphorous.

I've planted alfalfa, clover, turnips, and peas. All of them the deer around here seem to like.

I'm all the way across the states from you. I'm in Idaho, central Idaho actually. My plantings are in the middle of the woods too. Was a natural meadow, that grew some grass and weeds, but was nothing special. So I started planting it, and it just did so-so. So I started using a few different types of fertilizer to see what would happen, (although I already had a pretty good idea) But yes, I noticed immediately that the plants were growing stronger and taller, and also had a darker green color, whereas the areas that weren't fertilized remained a lighter green, with even a little yellow streaking.

I personally think that phosphorous may be the single best thing that you can fertilize with. It is a macro nutrient and one of its primary jobs in living organisms is the transfer of energy. Although care should be taken not to use too much around water, especially if you have a pond, as the phosphate group that is introduced will make algae grow, and deplete oxygen levels in the water for aquatic life.

I think that the phosphorous fertilizer gives the plants a boost, and they are probably more tender and juicy, because the deer do tend to prefer the fertilized stuff over the non-fertilized.
The bucks seem to really like to chow on it when growing there antlers too. Just wish I had more money to throw at getting a place set up.