What are some better alternitives?
There are heaps of alternatives to traditionally fed grains, and most are just as easy and about the same cost wise.
I personally use Speedi-Beet as a base for everything, it is just so handy. Low in starch and sugar, classed as a forage but a similar energy content to oats, it helps buffer the gut when feeding more concentrated feeds, soakable so they can't sift out anything yucky...
More options (All lower in starch/sugars than grains):
Basically the idea is to provide energy through fats, which horses are quite effective at utilising, as opposed to sugar/starch, which they aren't well equipped to handle.
Hay cubes are also a fantastic product.
A balanced diet it the best way to healthy hooves - Supplements only work if the horse is deficient in the first place - And most horses get sufficient biotin through grazing. I would look more toward correctly balancing her diet overall, and then hoof health would take care of itself.
I can highly reccomend feedxl.com - It is a program that helps you balance your horses diet when you key in their details, living arrangements, and then the feeds you use. Fantastic program.