In feeding an easy-keeper (those with the "thrifty" gene :-)), a prone-to-founder horse, or a potential insulin resistant horse, you can supplement with non-molasses beet pulp.
Potential or suspected insulin resistant (IR) horses may display some of
the following symptoms: excessive drinking and urination, patchy fat and / or
large heavy crest, any chronic laminitis, any laminitis /founder which seems to
be from underexercise and overweight.
It is very important to reduce the amount of sugar for the above types of horses. The non-molasses type of beet pulp generally can have anywhere from 5 to 10% sugar with a glycemic index of 1 which means that it does not have much affect on blood glucose levels. Oats has a glycemic index of 100 and bermuda hay has a glycemic
index of around 20.
From The Horse (2/03) regarding beet pulp written
by Ray Geor, BVSc, PhD (equine exercise physiology), Dipl. ACVIM:
"Plain beet pulp is a low-glycemic feed--there is little rise in blood
glucose as most of the energy is provided in the form of volatile
fatty acids, products of the fermentation occurring in the cecum and
large colon. Therefore, beet pulp can be classified as a source
of "calm energy."
The ratio is approximately one pound of beet pulp equal to 1.5 lbs of average grass hay, with some estimates being closer to 1 : 2.
One of the ingredients in the Cushings cube is also
Generally the beet pulp is rinsed a couple of times before feeding. It comes in a couple of different types, shredded and pellets, molasses added, plain. If you cannot find plain beet pulp, rinse it until it becomes clear. You may want to rinse / soak your hay to relieve it from sugar also.
There should be no other sources of sugar for these horses: no grain products, no senior feed, no carrots, no apples, no manufactured treats. Some of these horses cannot tolerate alfalfa.
Some owners have had success in supplementing with cinnamon, approximately one teaspoon per 250 pounds, for IR horses. See the EC Files section for more info.
If you need to feed treats (not that horses need them :-)), here is a list of acceptable treats as recommended by Dr. Kellon:
 No grains, flour, processed fats, sugar,
 No human foods such as breads, cookies, pasta, or baked horse
 No fruits.
 No carrots or apples.
Even a very small amount of the above can set off an IR horse. (BTW, it is suggested NOT to bed on straw.)
Things to use in place of the above:
 A bit of his normal hay or acceptable pellets (bermuda).
 Small amount of apple peel (no chunks of fruit attached)
 Tablespoon of low fat, plain, unsweetened yogurt
 Shells and papery outer covering of nuts (save those peanut, pumpkin seed,
sunflower seed shells)
 Small palmful of shelled peanuts, pumpkin seeds, sunflower seeds, soybeans
(not roasted, flavored or fat added)
Adding oil will blunt the glycemic response to a single feeding, but using it chronically worsens insulin resistance in ponies for sure, quite possibly in horses as well - especially if they were insulin resistant to startwith.
Wheat bran has a high carbohydrate count, so be careful of its use.
Balancing minerals with the hay and beet pulp needs to be taken into consideration. Rice bran is the best / most concentrated phosphorus source, however, take care in feeding too much.
Poor bone quality is going to be the
consequence if you don't. We stay away from wheat bran with IR horses and use rice bran, SMALL
amounts, just to balance the calcium in the beet pulp and to get some omega
fatty acids into them.
For growing horses, a 50:50 mix of oats (some Icelandic Horses don't tolerate oats, my gelding is an example of this as he gets very "high" in a nervous reactive way with oats)
and beet pulp is good as a base for supplements. This
blend is already major mineral balanced and you can use it as a
carrier for the other minerals you need. Beet pulp has a calorie
density equivalent to plain grains but since it soaks up to a very
high volume you end up diluting the calories by a factor of about 4.
The moist pulp holds minerals very well.