I have only had my horses a short time, but I soak my food in the garlic extreme, they say it helps to entice them into eating. It seems to work ok, and works well with our reef fishes as well. My horses are pigs really, and my largest one is a female and she's a glutten, she's gotten fatter since I've had her...3 weeks now.
I feed both hikari and PE, the PE is quite large so the smaller pair I have don't eat as much of that as they do the hikari. I switch off during the day so that they all get something they enjoy. I even tried enriched brine too, but I know it's not great for them so I feed my corals in my grow tank that on occasion when I'm lazy LOL