by Dr. Clair Thunes PhD, Nutritionist for EnviroEquine & PET ~

Lush green pastures are something many of us dream of for our horses. Sometimes referred to as Dr. Green, pasture grass does the equine body good. Of course, there are horses that for medical reasons such as equine metabolic syndrome can not be out on grass and others such as show horses who rarely get to spend time on quality pasture.

Beyond the almost constant eating that pasture provides which benefits digestive health, good quality pasture grass has something up its sleeve that many are not aware of, and an abundant source of natural bioavailable vitamin E. Studies of multiple grass pastures suggest that horses on quality pasture easily consumed an estimated 2000 IU or more natural vitamin E per day. This greatly exceeds the National Research Council’s recommended daily intake of 1000 to 1200 IUs per day for an average sized horse in moderate to heavy work.

With grass being such a great source of vitamin E, you might think that the same would be true of hay. But this is not the case. Vitamin E is not heat stable and so in the process of hay making where the grass is cut and then lies in the sun for several days to dry, the majority of the vitamin E content is lost. This means that horses consuming hay-based diets are typically consuming diets deficient in vitamin E. At this time of year with many horses being brought off pasture and pasture quality dropping, additional supplementation of vitamin E may be necessary. This is also true for horses with only limited access to pasture or if the pasture is lower in quality.

You might think that this is ok because you are feeding a fortified commercial feed or supplements that contains vitamin E so that your horse’s needs are in fact being met. And you might be right but it is quite likely that despite this fortified product you may be wrong. Your horse may in fact be deficient even if you are feeding many of the vitamin E supplements commonly available on the market.

Research has shown us that natural forms of d-alpha-tocopherol are better absorbed from the digestive tract than synthetic forms such as dl-alpha-tocopherol. However, there is large variation between horses on how they utilize vitamin E once absorbed and this is part of the problem. Just because you are providing sources of vitamin E in feeds and supplements, at levels that meet or even exceed the daily requirement, there is no guarantee that the daily requirement is actually being met at a cellular level.  The only way you can tell is to have your veterinarian conduct blood work and test your horse’s actual vitamin E levels.

If it turns out that your horse does in fact need additional vitamin E the very best form of vitamin E to provide is in a water-soluble form such as Emcelle Tocopherol from EnviroEquine. This research proven form of the vitamin is the most bioavailable on the market. This is because once water soluble, it does not rely on fat for absorption (vitamin E is a fat-soluble vitamin). This form of the vitamin will raise serum vitamin E levels in a matter of hours and is considerably cheaper than other sources when you consider its effectiveness.

Does vitamin E status really matter you might wonder? The answer is yes, although how much it matters will depend on the horse’s individual genetics, how long the deficiency lasts and when the deficiency occurs during the horse’s development. Vitamin E is a vital antioxidant necessary for proper neuromuscular function. Horses with vitamin E deficiencies will have poor exercise recovery, muscle weakness and soreness. They may also struggle to build and maintain topline. More seriously though, there are a number of conditions linked to long term vitamin E deficiencies that include a vitamin E deficient muscle myopathy and equine motor neurons disease. In genetically susceptible foals fed insufficient vitamin E, equine neuroaxonal dystrophy can occur which is a degenerative condition that presents somewhat similarly to wobblers. It is typically recommended that a broodmare’s vitamin E levels be increased in the last month of pregnancy to make sure adequate vitamin E is passed to the foal in colostrum and that foals should be supplemented prior to, and during weaning.

Clearly, ensuring that horses are consuming adequate vitamin E is very important. In horses tested as deficient, levels should be retested after about a month of supplementation to ensure adequate levels have been reached. How much will need to be supplemented will vary based on each horse’s individual utilization.  Keep in mind that too much is not always a good thing. Supplementing excessive amounts, over 10,000 IU per day, can lead to issues with bone mineralization and blood coagulation.

If you have questions or concerns about the level of vitamin E in your horse’s diet reach out as we are happy to help. Meanwhile, consider reaching out to your veterinarian to have your horse’s vitamin E levels assessed.