Replenishing nutrients when bathing daily

[irishsaints]

So I know that there are a fair number of people in the world who bathe their horses daily, especially show horses. A friend of mine was riding one such horse for a while, and bathing him after every ride, and also giving him special oils and feed mixes to help restore the horse's natural oils.

My question is, if I were to do that, what sort of things would I need to add to my horse's feed in order to help his body maintain those oils and minerals, etc? (This is all very hypothetical, of course.)

Thanks!!