supplement help

okay hi! i asked in an equine nutrition group on facebook but i got mixed answers, so i was wondering what supplements i need to add for my horse to help get him all the nutrients and minerals he needs. i’m not looking to change his grain since he’s hard to keep weight on and this grain is doing the trick, but if you have any other suggestions i would appreciate! here is what he’s getting daily;

about 8 flakes of grass/ alfalfa mix quality hay, out at night so he’s grazing on grass 3lb of triple crown senior am&pm 1scp hoof secret 1scp apple-a-day electrolytes

he’s a good weight, but i was looking for supplements to maybe improve topline growth. he’s in pretty consistent work (about 5 days a week) i was getting suggestions on vermont blend, but it’s a little out of budget for me. and as well as to switch to just plain salt but i’m unsure of what i would go to. any suggestions? i would love reasoning, why and how it helped your horse. thank you!!! just trying to do what’s best xD