The Myth of Balanced Feeds
Some feeds claim (or at least strongly suggest) that they will provide your horse with everything he needs in terms of nutrition, and in the optimum amounts. In fact, many people are afraid to stop feeding grain mixes because they believe the horse's diet will then be unbalanced and/or the horse will miss out on nutrition.
What you need to understand, though, is that your horse's nutrition needs to be looked at in terms of everything he eats - both hay/pasture and what might come out of a bag. It may be true that what's in the bag is balanced, or even contains enough vitamins and minerals for a day at a certain level of feeding. But that doesn't make the whole diet balanced unless it's the only thing the horse is eating.
For example, the diet should ideally contain about twice as much calcium as phosphorus. If you're feeding alfalfa or your horses are grazing on a pasture with a lot of clover, they are getting way too much calcium compared to phosphorus - six times as much, if not more. Feeding them a grain mix that has a balanced 2:1 ratio won't help matters any. You would be better off feeding plain grains and wheat bran, which are naturally higher in phosphorus than calcium.
Have you ever heard the adage that all a horse needs is hay and oats? Do you remember when the major controversy was oats vs. corn, or when sweet feed and bran mashes were exotic?
Today, if you go to the website of just about any feed company, or to a feed superstore, you'll find an astonishing array of different feeds to choose from. Often, these are so varied and complicated that the manufacturers have to provide feeding calculators or other product-selection devices, and even then you may end up with 10 or more choices. "Low carb" is particularly trendy these days. What do you do? What does it all mean?
It's impossible to feed your horse a low-carb diet. The bulk of the calories, even in grasses and hays, is carbohydrate. What matters is the type of carbohydrate.
The carbohydrate in your horse's diet comes from sugars, starches and fiber. Fiber is a complex carbohydrate that the horse's intestines can't digest, but the organisms in his large bowel can. The horse then uses the byproducts of that bacterial and protozoal fermentation of fiber as an energy source. Fiber is further broken down into water-soluble (dissolves in water) and nonsoluble fiber, with the soluble fiber being much more easily fermented and therefore yielding more calories.
Sugars and starches are digestible in the small intestine, and most are broken down to glucose before being absorbed. The calorie yield from simple sugars and starches is higher than from most fibers, and grains or molasses are many times higher in sugar or starch than hays and grass.
More horses and ponies get grains/concentrated feeds than actually need them. But before going into that, it's important to remember that grains are not poisons and they do have a place. The horse is designed to eat grass, not grains, and should always be fed as much grass or hay as he can eat before you consider feeding grains.
In most cases, only the hard-keeper breeds like Thoroughbreds truly need grain on a regular basis, or horses that are in hard work. Even pregnant, nursing and growing horses can do well and hold their weight on minimal to no grain as long as their protein and mineral needs are also being met.
Unfortunately, owners derive a great deal of pleasure from "feeding" their horse a grain meal because the horses obviously enjoy it and look forward to it. Too much grain and too little formal exercise have led to an explosion of health problems.