Alfalfa, corn, and some specially designed feeds give the horse allot of energy, but fed in excess, rich food like alfalfa will cause fatal stones in the horses stomach that require surgery to remove. Corn has little protein for horses, and is not a good meal for your horse, and you need to look at the ingredients in the food, to make sure it has all the other nutrients the horse needs and that it does not have too much bad stuff in it.
corn corn
oats that's my guess
On talking about a horses diet he needs everything in a fair amount.
on your horse's page press feed and select the amount that your horse needs then press feed again
Corn usually provides the most energy for horses. also Rolled oats.
howse answer riding level 3 - corn
You feed your horse by clicking the feed link to the top left of his page and selecting the amount of forage and grains to give.
When a horse is under weight you should feed him the full amount of forage/fodder that is Possible then age them with an aging point and feed them the full amount! happy howrsing!
Horses are given grain to provide extra calories which provide extra energy. Straight grains such as corn, oats and barley have been used to feed horses for hundreds of years, but do have a down side as they make the horse 'hot' or excitable and if given in too large an amount can cause obesity problems and even Lamanitic changes. Processed grains or horse pellets are safer to feed and come in a wide variety for specific purposes. The only reason to feed these is if the horse needs the calories, so they should be in moderate or higher work, pregnant, growing, a hardkeeper, or has dental / chewing issues.
Horses need a certain amount of minerals. Ask your vet which type of horse feed is best for your horse. here's the types of vitamins and minerals a horse needs: http://alpharmaequine.com/info-vitamin-mineral.html and here's more about horse's energy: http://alpharmaequine.com/info-vitamin-mineral.html
You feed the horse the most allowed amount, in hope to get it back to it's original weight. You will have to check back everyday, or over feed the horse if you won't be on every day
You will need to feed the next highest amount available on the drop down menu. Or you can feed 13 pounds and then get the remainder by putting the horse in the meadow.