Vitamin E

Vitamin E is an essential nutrient and important antioxidant for horses. While horses on fresh pasture grass generally meet or exceed daily requirements for vitamin E, many horses live with limited to no access to grass and require some level of vitamin E supplementation in their daily diet.

Recommended daily intake of vitamin E is based on the NRC requirements for horses and is 1-2IU/kg of body weight (500-1000 IU for an average 1100lb horse) per day, with a safe upper limit of 10,000IU per day.

A few things worth noting...

1) These recommendations are based on "minimum" recommended amounts to avoid serious deficiency issues, but not necessarily recommended "optimal" levels.

2) These recommendations are based on synthetic vitamin E (dl-alpha tocopherol). Natural vitamin E (d-alpha-tocopherol) is approximately 3x more bioavailable than synthetic (meaning more absorbable) and water-soluble vitamin E is the most bioavailable, which increases serum levels the fastest, but not necessarily any more beneficial at maintaining long term status than the other forms.

3) If your horse is on quality green pasture for at least half the year turned our for at least 10+ hours per day, they can consume enough vitamin E during the summer months that will be stored and potentially fulfill their winter requirement. That does not mean that one should stop providing a source of vitamin E in the daily diet, but it is stored long-term, unlike much of the other required nutrients. Providing a balanced diet with some added vitamin E (either synthetic and/or natural source) is always a good idea.

4) However...the only way to know if your horse is truly getting enough vitamin E is to test the blood. Late winter is a great time to test the blood for baseline levels of vitamin E, especially if there is limited access to fresh grass. We strongly encourage you to work with your veterinarian and equine nutrition consultant to establish an appropriate level of supplemental vitamin E for your horse based on baseline blood tests.