as she has a crack in one of them that got infected a few months ago. She is barefoot, I'm wondering what you guys would recommend?
Feeding a good supplement will help in the future because it will strengthen the hooves.
It won't help now. I am interpretting that the crack is still there and if it is, it's still got a fungal infection in it and needs cleaned daily.
If you have something in your country to dry up milk cows so they don't get mastitis, that is what I use. Here it is called ToMorrow or ToDay.
It can be cleaned by soaking the hoof daily in a mix of warm water/iodine/clorox.
Use enough iodine to make the water dark brown. Only use a capful of clorox
(In water deep enough to cover the hoof). Clorox is something that more is NOT better.
Pat dry and shoot the cow dry into the crack.
If you can't get cow dry, get some sort of people anti fungal cream
from whatever store you shop at and force it down into the crack.
In order to heal the crack, this will have to be done at least once daily but twice daily is better.
While hoof oil is a good thing for dry hooves, it will not do anything to help heal the crack when there is fungus in there. It may even make the issue worse.
Not a fun task
I deal with this every summer with one of my horses because our ground is very acidic in my area and very prone to fungus.
He is barefoot, trimmed every five weeks, his hooves get faithfully oiled, and I don't care what I feed him, he still gets cracks that won't heal unless I soak them and put some kind of fungus fighting cream or the cow dry in them.
Hope this helps