Feeding & Watering

A normal, 1200 pound horse can be fed one scoopful of grain a day, and one flake of hay in morning and night in the warm months, and two flakes, in morning and night in the cold months. Ask a horseman or veterinarian if you need to make adjustments.
A flake of hay is about 1 or 2 inches thick. Hay tends to come of in slices. Each slice is a flake.
The scoopful can generally be a coffee can. Not the very large size--just the normal size. If you ride the horse nearly every day, give a scoopful in the morning and a scoopful at night.
A Miniature horse or small pony can be given half of the rations a 1200 pound horse is given.
As I said, ask a veterinarian to be sure.
Watering is simple. Be sure your horse always has fresh water. Always wash all backwash, etc. out of the stall water bowls before refilling them. Pasture water should be washed out fairly regularly, but not as regularly. The reason it should be, is because this prevents disease.
A 1200 pound horse generally drinks from 10-20 gallons of water a day; hot days, obviously, they drink more, so be sure your horse always has enough water.