I don't know how you'll take this,but 30 years ago their were no supplements.not in the form I see being produced today.and the dogs in general were of much better stock than whats rollin out now.
maybe their is a need for supplements.
I have used nupro, and to be perfectly honest, I didn't see enough of a difference to stay using it. I tried it during part of my show season in 2010. When I stopped using it I didn't see any kind of difference in what I normal feed during conditioning.