Been playing with a stump feeder since last march and have a new 230# hanging feeder on its way here now that I plan on putting up soon. If you can afford it, Reb introduced me to the Purina Deer chow also and went and looked at it in or local supply and it seems like it is good stuff. It is supposed to have 20% protein in it and also have lots of the others for deer racks too, like calcium and phosphorus. If you have the money then I would fill it with that. But I am trying to save a few bucks and will be making my own mix. I plan on doing a 25% mix of corn, rolled oats, Deer Chow, and soybeans. I will put the link at the bottom that I found on here that will tell more about them, but soybeans are supposed to be the highest in protein. Ranging from 35 to 45%! Read the link to get more details. Making my own mix will save me about 25% on the cost but its worth a try for me. But from what others like Reb and people at the local supply say the deer chow is good stuff and they eat it up well too!
http://www.deerhunters.net/articles/nutrition.htm