Had to look this up, with a name like that, before I made some silly comment!
So obviously no, don't know about it personally, but high selenium is one potential issue, which can be very serious. Considering it's a mix of prods which have similar ingreds, there could well be ODs & imbalances of other nutrients. Of course whatever nutritional supplement, it also depends on the horse's diet as to the suitability or otherwise of this. In addition the 'product overview' lists products in the TNT of which there is little/no info on their site for, so who knows what's in them.