I don' t think you will be able to attract the deer with hay bales at this time of year. Too much green forage, that is if your spring was as wet as around here. In the dead of winter when nothing is available they might go for it. If you can put in a small splot of Buckwheat, annual rye mixed with some Ladino clover, you have a better chance of attracting deer. If you set out hay, after a few rains it will mildew, and then it' s done for. Nutritionally, hay is used to feed livestock when nothing else is available and is usually supplemented with some cereal grains such as corn oats, etc. Maybe someone else on here may have some more ideas.
Russ