Diet makes all the difference in the world.
Pasture and hay quality can even make a difference.
Here's the link to another thread where "EmilyJoy" posted a link to Pete Ramey's site that discusses the importance of diet. Pete Ramey- Info on diets regarding hoofs etc.
I should've never seen this because I am going to throw it out there every time I see the need --- yes, I bookmarked the entire thread
What's wrong with hooves and coat can't be fixed from the outside until it's addressed from the inside. Granted some horses will respond better than others due to genetics but, it has to start with diet