Horse feed please helppp?

Hello. I have a 8 year old thoroughbred mare. I have just switched her over to a new farrier and was told that her feet are horrible and have been shod the wrong way for years now. My vet confirmed this. The farrier told me that I need to start giving her some sort of hoof supplement so what is the cheapest and most effective? Also, he said to give her alfalfa because that will help the most. I can't give her bales of alfalfa because where I am boarding the lady won't give it to her because it conflicts with the other horses. Should I give her pellets or cubes? I was considering the cubes because she can put them in the morning feed, but i was nervous about not soaking them. I go to the barn 3-4 times a week so I could feed her it then but how do i soak it and how much should i give? I also heard that gelatin helps but is it not as effective as biotin? Please help me!!! Thank You