re: magnesium
I went looking for science articles that show the efficacy of magnesium on horses ( i.e. calming agent, attention improver, etc, )but all I could find in a quick search was a lot of hype by feed sales sites that sell magnesium. Not exactly the proof or evidence or information I was looking for. Supplements are a money maker for feed companies-- why wouldn’t they hype their product with vague statements of effectiveness? But those statements are advertisements, not scientific evidence.
http://www.horsehero.com/editorial?feat=83626
Here is something making claims in favor of chleated calcium and warning about magnesium, for instance.
There is a lot of conflicting information, some psuedo-science and very little in the way of objective science on magnesium.
I do have to wonder how much of the claims of chemical benefit are a sort of placebo effect in the rider’s mind.