vitamin supplement

[SoulsSerenade@aol.com]

Okay, my horse has a salt block....the red one that has all sorts of minerals 
in it.  She is on a small pasture that is...well, sort of...in the process of 
going bald....picture a 40 year old man.  There is still some hair, but it 
isn't as thick as it used to be....okay, I'm wandering off the topic here..
I feed her alfalfa and  the only time she gets any sort of grain is when I 
ride her.  And it is just so she can have a little "extra" something.  Her 
treat is usually no more than a cottage cheese container (the short one) of 
oats.  
She is a very healthy 6 year old horse...and her coat is nice and shiny (as 
shiny as possible when she is always coated with a thin layer of dust)  So, I 
guess my question of the day is....should I be feeding her a vitamin 
supplement??? Her farrier (and former owner) says she has good feet (she 
better have great feet if her old owner was a farrier!!!!)....And I always 
thought that if there was something missing in their diet, their feet might 
start to look...well....not so hot.  
Okay...have at it....I'm ready....let 'er rip
thanks a million, billion, trillion, kazillion
-Renee