Don't over think it. they are coming for the salt, good old NaCl.

The vanilla scent might create some interest.

I use this in the summer in front of my cams. I also mix in some trace minerals, calcium, phosphorus, and sodium. And yes, I get it along with all affected soil out 10+ days prior to season opening to stay legal.

http://www.ruralking.com/salt-rock-...ium=cpc&gclid=CK-0hZaiwMgCFYo8gQodEusB2w

http://www.ruralking.com/salt-bag-trace-mineral-50.html

Check out this review of a study

https://www.qdma.com/articles/minerals-for-whitetails