I have a hard time buying into stuff like that. I think for you to see results would take several factors. I think the deer would have to eat alot of it in the first place, throughout the spring and summer. I also know for a fact you would have to have a really big block of land that is on strict management techniques.
I have about 190 acres, and while I am blessed and thankful to have it, I know that it isn't very big in the grand scheme of things as far as managing deer heard. I am sure that If I fed the deer some feed it could help, but I would basically just be feeding young bucks that somebody will shoot between opening day and Thanksgiving. It aint worth it to me.