RE: What kind of minerals?
I am not writing this to argue. The name of the man I gave you- Rod Marburger is the man whose study and research of whitetail nutrition is (in-part) the basis for the Whitetail Institute's nutritional program and product development.
I do not testify to anything I haven't experienced myself. I don't care what expert says this or says that, no more than I think the "experts" in our state know what is best for the future of our deer herd. I have done my research first hand and express what I have found to have made an improvement in the deer herd I manage.
As far as selenium being bad for deer??? Umm, OKAY! Why does nearly every reputable manufacturer of whitetail supplements use selenium in their products. Because they understand the negatives of what a selenium deficit in a deer's diet will do to health of the deer. Anything taken in excess in any living animal has potential risks. Responsibilty and Common-Sense needs to be taken when providing wild or domestic animals with mineral supplementation.
My advice to anyone else reading this.... Do your own research and come up with your own conclusions. Don't take my word as being gospel, rather it is my perceived results from the work that I have personally done.