RE: mineral blocks and salt
The trace mineral block containing copper that is used for cattle is also recommended for deer, but not for sheep.
I spread several throughout my hunting areas along with ground pits containing rock salt used for making ice cream. Just make sure the mineral blocks and the salt are not too close to your stand if your state has laws governing hunting over or near food plots.
The deer will start consuming the mineral block(s) and salt in early spring through mid summer.