It depends on your pony and his needs. I would do some supplements, and if he's being worked regularly and you have a hard time keeping weight on, fat and fibre grain. Etc... you need to adjust to your horse's needs. Ultimatly you'd have to ask your vet to know exactly what your pony needs for grain. I had a horse that worked 6 days a week and she only got hay and water as well as pasture, it honestly depends on the horse, breed, weight, work, age... etc. Good luck!!