Imperial Cutting edge has addressed that, but I'm afraid the jury is out.

Its difficult to artificially add protien to any wild animal's diet. Literally, you would have to feed hundreds of pounds, to a specific deer, to make much difference. For this simple reason, its seems to make more sense to offer quantity of high protein forage, or supplementally feed (not for me).

I like your thought process however - its good that you want to make a difference, mineral supplements is a good way, especially in certain areas of the country.