I woulddo both. I have a food plot and I have a large protein feeder at the edge of the plot. If feeders were so good at spreading disease, Texas would have the worst deer herd in the country (which they don't!). I'm not 100% sure about muleys, but I would give it a shot. You'll be very impressed with the results in antler growth. I gurantee you that it won't decrease your success rate. Supplemental feeding is very good for deer. There's no reason not to. Good luck!