I usually find if my horses do not like something to trust them. There is most likely something in it that they do not need…..If you have to mask it w/something sweet – not good. That in mind sweet feed is not a good feed. I would try a good quality enzyme (ABC or ?) to ensure he is receiving all the nutrients from the food that he is eating. This is a good starting point for just about anything (sometimes ProBiotics are needed also), and many times is all that is needed for supplementation to a good diet (low to no grain, hay, pasture, vit/min supplement). My old gelding (31 yrs) was thin and very lame. I tried many “supplements”. The last year he improved tremendously after I put him on ABC Fortified, ABC Enzymes, Timothy pellets (Semican), and Tim/Alfalfa minis (Semican). NO GMO’s. This improvement came even though he LOST HIS GRIND TOO!