Vitamin E serves as a powerful antioxidant to maintain many normal body functions of the horse. The vitamin is important to many areas of the horse’s body, including the eyes, neuromuscular system and reproductive tract. Of course, there are likely many other ways that it serves the body that haven’t yet been determined! Do you know if your horse is consuming enough vitamin E?
Where Horses Get Vitamin E
Horses consume adequate amounts of vitamin E in their diet so long as they have access to fresh green grass a majority of the year. Grass is a great source of vitamin E (and omega-3’s, too!) when grazed on, but levels quickly decrease after cutting. This means that hay, especially when stored for longer periods of time, can be a poor source of vitamin E for the horse.
How Necessary is Vitamin E?
Horses do not necessarily require vitamin E on a daily basis, all year long. Horses store vitamin E in the liver, and can draw upon those stores for the months where they face inadequate resources, such as during winter. Some say an adult horse with previous dietary intake of adequate amounts of vitamin E can go approximately 18 months without consuming any of the vitamin before problems become noticeable. Note that this does not look at when deficiency symptoms may be unnoticeable!
Of course, there are many horses that are not so lucky as to always have access to green grass even for part of the year. Whether or not a horse shows clinical signs related to a vitamin E deficiency relates to a variety of things. Factors that can lead to signs of deficiency include the age when the deficiency developed, how long the horse was deficient, genetics, and other components of the diet.
How Much the Horse Needs
The National Research Council recommends horses consume 1-2 IU of vitamin E per kilogram of body weight per day, which is around 1,000-2,000 IU per day for a 1,100 pound horse. A proper diagnosis of a vitamin E-related problem is made with a combination of vitamin E access, clinical signs, muscle biopsy results, as well as eliminating other diseases with similar signs. A normal vitamin E level for a horse is considered to be greater than 2 μg/ml.
Older horses have an increased need for antioxidants such as vitamin E. A study with predominantly older horses found that the bacterial killing capacity of monocytes and neutrophils (types of white blood cells) increased in the vitamin E-supplemented horses, but more research is needed in this area!
When to Add Vitamin E to Your Horse’s Diet
Unless your horse has access to fresh green pasture a majority of the year, incorporating a vitamin E supplement in their daily diet is a great way to ensure your horse does not develop a deficiency. According to UC Davis, alpha-tocopherol is the most biologically available and well researched isoform of vitamin E. Be careful where you source your vitamin E however, as there is a big difference between natural and synthetic.
If your horse has already developed a serious deficiency in vitamin E, you will want to consult with your veterinarian about adding a water dispersible form while also testing serum levels periodically. These are the most effective, but also the most expensive. Natural-source, powdered alpha-tocopheryl acetate requires over a month to increase levels to the normal range for the deficient horse. Adding a healthy amount of vitamin E to your horse’s diet proactively is the easiest way to combat deficiencies.
The National Research Council has set the upper safe diet concentration at 20 IU/kg of body weight, which is about 10,000 IU per day for a 1100 lb horse. Above this level, blood clotting and impaired bone mineralization have been reported. As mentioned previously, the low end of their recommendation is 1,000-2,000 IU per day for a 1,100 pound horse. Horses will receive some vitamin E from hay and any grazing they are able to do in addition to supplementation.
Omega grandE is a natural source supplement that provides 1,500 IU of Vitamin E per serving. Intended as a daily supplement and designed to keep your horse within the safe limits, it has a base of ground flaxseed and plain dried beet pulp which make the D-alpha-tocopheryl acetate highly palatable to horses. Feeding Omega grandE daily can fill the gap in vitamin E intake for horses without grass pasture, or your older equines who need some extra care.