I buy the large size of triple antibiotic and desinex (really large, cheaper by the ounce) for thrush.
I buy whichever is cheaper (vet or human label) of the large size of providone for my family medicine "cabinet" and put what I need for the horses in a spray bottle. There is no difference between the two.
I take whatever volume of bran mash I need when I need it out of my cabinet (to mix w Epsom salt for wound care).
I use dr. Bonners castile or ivory liquid soap for bathing, cleaning blankets, etc.,.
Tide for whitening mane and tails.
Peppermint oil for "happy" baths (a few drops).
Pure powdered sulfur (dirt, dirt cheap) for use on wounds straight or mixed with "inside" ingredients like cocoa butter or Vaseline.
For horse cookies I take all "out of date" packaged mixes and make a batter and bake them up.
Any apples, bananas, carrots, granola bars, whatnot that need to be eaten but there are no human takers...hello, horses.
Edit...Well, rereading OP's original post, this isn't nutrition except for the treats and fruit. :)