the active ingredient in myoplast is blue green algae which also goes by spirulina.
Preface by saying all three of these horses have hay all the time.
The 3rd level dressage horse (starting to school 4th), has a tendency to get very… pudgy… and has a small hole nibble net. If it was up to him he would eat enough that he wouldn’t be able to fit through a door. So for grain he doesn’t get much, but gets a vitamin/mineral supplement. His topline improved a lot and he started really packing on muscle, without adding extra calories.
Horse 2 is an older TB who started on it while he was out of work temporarily due to a nasty abscess because his topline was disappearing fast and he was starting to look old. That was a year ago, his muscling all over bounced back fast, and has actually been maintained even though he’s temporarily out of work again (lack of time). This horse is a slow picky eater, so getting him to consume enough of anything is a battle on any given day.
Horse 3 is a combination of 1 and 2. TB, but young, who gets fat easily. He was an experiment horse, since we weren’t sure we’d go 3/3 with supplement success. It’s helped him fill out a lot, especially for him with muscle on his hindquarters.
Whether it’s related to the myoplast or not (but we don’t change much if things are working), I think the 2 TBs feet are standing up to winter better than previously. Both have shoes in front, but are barefoot behind. Despite our wacky, thaw/freeze/rain/ice/thaw repeat weather we’ve been having in Ontario, neither of their back feet have chipped.