My adult horses get grass hay twice a day, minimum 16 lbs per day, plus 1 lb of Purina Born to Win per day split into two feedings.
My old man (32 yr old spry thing) gets 12 lbs of Purina Equine Senior plus 1 cup of vegetable oil split into two feedings per day and soaked to make a mash since he's pretty well toothless. He also gets a small flake of hay twice a day just because he wants to gum some after his feed. But he never finishes it and just stands and dozes while the other horses clean up for him.
They are all on pasture as well and we are getting grass coming in again. Once the grass is in well, I will cut out the feed and hay for the young adults, but the old man will get the same Senior feed all year round.
Licensed Veterinary Technician