Do Horses on Fortified Grain Need Supplements?

Updated August 19, 2024 | By: Dr. Lydia Gray
grain being poured into a horses feed bucket

"Hi, I am really worried and all this is very confusing. We just had a horse nutrition talk at our barn and they said that we do not need to add supplements to the horse feed, that the horse feed already comes with all the nutrients and vitamins balanced, that we can cause an unbalance especially on vitamins and minerals, and this is going to be against our horse’s health. I am talking about commercial feed on pellets from the big companies, especially formulated for senior, junior, mares and high performance horses. Am I overdoing and putting my horses at risk?"

- GE, Texas

Dear GE,

I know exactly what you’re talking about and I think I can easily clear this up for you. When a commercial horse feed company representative talks about causing an imbalance of nutrients by feeding a supplement in addition to their product, they’re talking about “doubling up” by feeding the full recommended amount of fortified grain on the bag as well as the full recommended amount of vitamin and mineral supplement.

However, there are certain situations when a horse needs a vitamin and mineral supplement, such as when a horse is not being fed the full recommended amount of fortified grain or when a horse is not being fed fortified grain at all.

The Problem with Calories and Nutrients in Fortified Grains

You see, fortified grains were originally designed for hard-working horses that needed a lot of calories. Vitamins and minerals were added to grains such as corn and oats to provide race horses, draft horses and other horses that worked for a living all the nutrients they needed.

The problem with most fortified grains is that calories are tied to nutrients. That is, if an owner needs to increase the amount of fortified grain fed to a hard-working horse to keep him from losing weight (like one that competes in three-day eventing or endurance riding), the amount of vitamins and minerals he’s getting is automatically increased.

However, because most horses don’t work this hard for a living, the opposite problem occurs. That is, with more and more owners becoming aware that medical problems like Equine Metabolic Syndrome, laminitis and even arthritis are made worse by obesity, they’re cutting back on the amount of fortified grain they feed their horses, if they feed grain at all. Now you have a situation where a horse isn’t getting enough vitamins and minerals because the full recommended amount of fortified grain isn’t being fed, in an effort to reduce calories.

Ensure Your Horse Gets Enough Key Nutrients

That’s where a vitamin and mineral supplement or ration balancer comes in. By adding the appropriate product to a horse’s diet, his vitamin, mineral and even protein (amino acid) needs can be met without adding extra calories. Some vitamin and mineral supplement—like SmartVite and Mega-Cell/Mega-Mag—are even designed to complement the type of forage a horse eats, whether it’s grass or alfalfa.

Finally, let’s talk about addressing specific problems in a horse, such as poor quality hooves and joint wear and tear. When picking supplements based on your horse’s needs, feeding multiple products does not necessarily mean that there’s an increased risk of over supplementation. In fact, a well-designed “strip” of SmartPaks with multiple products may actually be more appropriate (and necessary!) than one that contains just a couple of similar products (like 2 vitamin supplements!).

Building a Balanced SmartPak for Your Horse

Here’s an example of a SmartPak that may seem large at first, but is actually quite thoughtfully put together:

  1. a vitamin and mineral supplement
  2. a joint supplement
  3. a hoof supplement
  4. an electrolyte supplement

Each of these types of supplements contains specific ingredients designed to address specific needs. As such, there’s very little overlap.

The point is: do your best to provide your horse with a complete and balanced diet primarily consisting of good quality forage (hay or pasture) then make up any specific deficiencies with a vitamin and mineral supplement and other products as necessary.

Video on When Supplementing May Become Too Much

In this Ask the Vet video, Dr. Gray answers a horse owner's question on when giving certain types and amounts of supplements can be overdoing it.


SmartPak strongly encourages you to consult your veterinarian regarding specific questions about your horse's health. This information is not intended to diagnose or treat any disease, and is purely educational.