Vitamin E is an essential nutrient that is often not provided in great enough quantity through the horse’s forage.

While fresh grass is a good source of Vitamin E, the stability of Vitamin E in harvested forage is low; therefore, a hay-only diet must be supplemented with Vitamin E. Also, the horse in work may not receive enough Vitamin E from fresh grass alone to support their needs. For this reason, adding supplemental Vitamin E to fortified feeds is a common strategy.

Vitamin E plays multiple roles in the horse’s body. It works in concert with many other nutrients as an antioxidant, which protects the body against damage from free radicals. Free radicals are a normal byproduct of metabolism, but the body needs to be equipped to counteract their impacts to stay healthy. Free radicals that aren’t addressed by antioxidants can cause muscle soreness and delayed recovery from exercise. Vitamin E specifically prevents lipid oxidation. Fat, which is composed of lipids, is used throughout the body in many ways. Lipids make up cell membranes, are building blocks of hormones, and can be used as fuel for energy.
 
Part of Vitamin E’s role as an antioxidant is to support normal neuromuscular function. Equine Neuroaxonal Dystrophy and Equine Degenerative Myeloencephalopathy are diseases that have been traced to Vitamin E deficiency in young horses and adult horses. Horses with long term Vitamin E deficiencies can develop Equine Motor Neuron Disease.

The National Research Council (NRC, 2007) has identified the following as the minimum Vitamin E requirements for an 1,100-pound horse.

  • Idle: 500 IU/day
  • Light Work: 800 IU/day
  • Heavy Work: 1,000 IU/day

More recent work suggests that these requirements may be on the low end, particularly for horses on higher fat diets. For that reason, we formulate to exceed NRC requirements for Vitamin E in all Tribute® Superior Equine Nutrition feeds.

Since Vitamin E is an important nutrient, it is often supplemented by horse owners. If feeding at least the minimum recommended quantity of a Tribute® product that is appropriate for your horses work level and size, additional Vitamin E should not be required for a horse without other underlying health issues.

Vitamin E is one of the few nutrients that can be measured in the blood with a high level of accuracy and before embarking on Vitamin E supplementation, it is recommended to check the horse’s Vitamin E status. The good news is that Vitamin E has a wide toxicity range, which means you are unlikely to cause health issues with too much Vitamin E, but the added cost of unnecessary supplementation could be spent in many other ways to support your horse’s wellness.  

The form of Vitamin E is important, but often misunderstood. Synthetic Vitamin E (dl-alpha-Tocopheryl Acetate) tends to get the bad rap, as it is less bioavailable than natural (d-alpha-Tocopheryl Acetate) Vitamin E. However, it is important to remember that less bioavailable doesn’t mean it is not bioavailable.

Natural Vitamin E is our first choice when addressing an acute Vitamin E deficiency because it raises serum Vitamin E levels more quickly, but synthetic Vitamin E is appropriate and effective for maintaining a healthy Vitamin E status.

Synthetic Vitamin E does hold the advantage in maintaining stability over time in stored feed, which makes it a useful addition to horse feeds, even though it has a slightly lower bioavailability than natural Vitamin E.

Tribute® Superior Equine Nutrition feeds utilize a combination of natural and synthetic Vitamin E. This allows us to take advantage of the higher bioavailability of natural Vitamin E along with the stability of synthetic Vitamin E to best support your horses nutritional needs.

While Vitamin E gets a lot of attention, we can’t forget that it is just one piece in the larger puzzle of developing a balanced diet to support your equine partner. Our team of equine specialists can help you put together personalized nutrition plans for each of your horses to ensure all of their nutritional needs are met to best support health and wellness.

Nicole Rambo, Ph.D.