03/25/2025
The antioxidant value of E is just one of the many benefitsโฆ
๐ฑ ๐๐ข๐ญ๐๐ฆ๐ข๐ง ๐ ๐๐ง๐ ๐๐จ๐ซ๐ฌ๐๐ฌ ๐ด
Vitamin E is an important antioxidant that works to maintain healthy muscles and nerves. While vitamin E is plentiful in fresh forage, it quickly becomes depleted when forage is cut and preserved as hay. As a result, horses lacking access to at least six hours of quality pasture a day (often due to dry lot confinement or seasonal changes) may become deficient in this critical vitamin.
๐ฌ ๐๐ก๐๐ญ ๐ญ๐ก๐ ๐ซ๐๐ฌ๐๐๐ซ๐๐ก ๐ฌ๐๐ฒ๐ฌ
Previous research has found between 13 and 20% of horses are deficient in vitamin E (Muirhead et al., 2010; Pitel et al., 2020). However, when we tested horses at the local University who received hay and a free choice vitamin and mineral mix, up to 74% of horses were deficient in vitamin E. While grazing in the summer helped increase average plasma vitamin E concentrations, 59% of horses were still deficient after grazing for 3.5 months (hoping to publish this data soon if I can find time to write!). This data emphasizes the importance of evaluating vitamin E in the horseโs diet and verifying the efficacy through blood testing.
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While not all deficient horses demonstrate clinical signs of the deficiency, weight loss, muscle atrophy and weakness, as well as increased lying down, may be observed. More severe cases may result in neurological impairment. Thankfully, we continue to learn more about this deficiency which allows us to prevent and manage it more effectively.
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๐๐๐๐ข๐ง๐ ๐ญ๐จ ๐๐๐๐ญ ๐๐๐ช๐ฎ๐ข๐ซ๐๐ฆ๐๐ง๐ญ๐ฌ
When I balance a ration, I like to ensure horses receive the recommended levels of vitamin E in their feed โ I consider any additional vitamin E provided in forage as an added benefit. This is because our management practices, including dry lot confinement and poor pasture management, often necessitate the addition of vitamin E in the diet, at least during part of the year. To do this, you can simply provide a fortified commercial feed based on the manufacturerโs recommendations. However, if you are feeding less than the recommendations on the feed tag, the horse will be lacking in critical vitamins and minerals, not just vitamin E.
However, it is important to note that horses may still be deficient even if they technically meet requirements according to the feed label. But why?
1๏ธโฃ Well first off, horses can metabolize vitamin E differently. So while a horse may meet their requirements based on the label, they may remain deficient due to individual differences in how they utilize the nutrient.
2๏ธโฃ Vitamin E is not very stable and can be compromised if not stored or handled properly. If this is the case, the horse may not actually receive what is promised on the label. While I am not worried about this when I am handling a product from a reputable company, it highlights the importance of using a tested product from a reputable brand and ensuring you store it according to their directions.
โ๏ธ ๐๐จ ๐ก๐จ๐ฐ ๐๐จ ๐ฒ๐จ๐ฎ ๐ค๐ง๐จ๐ฐ ๐ข๐ ๐ฒ๐จ๐ฎ๐ซ ๐ก๐จ๐ซ๐ฌ๐ ๐ข๐ฌ ๐ซ๐๐๐๐ข๐ฏ๐ข๐ง๐ ๐๐๐๐ช๐ฎ๐๐ญ๐ ๐ฏ๐ข๐ญ๐๐ฆ๐ข๐ง ๐?
The most accurate way to determine if your horse is meeting requirements is through a blood test. I prefer to evaluate plasma or serum vitamin E moving into spring, before my horse has had access to fresh grass (you can have your vet pull blood when they are pulling a coggins). I find the spring to be one of the most beneficial times of year, as this is when horses are most likely to be deficient. However, a lot of horses will show a deficiency within a few months after they are removed from fresh grass. So if you test in the winter and catch a deficiency sooner, you can correct it quicker. Either winter or spring timing also allows you to determine if your feeding plan over the winter is effective. Once you receive the results, you can tailor your diet accordingly to meet requirements!
๐๐ก๐๐ง ๐๐จ ๐ฒ๐จ๐ฎ ๐ง๐๐๐ ๐ญ๐จ ๐ฌ๐ฐ๐ข๐ญ๐๐ก ๐ญ๐ก๐ข๐ง๐ ๐ฌ ๐ฎ๐ฉ?
If your horse is not deficient on the blood test, keep on doing what you are doing! At this point, more vitamin E has not been proven to be better and it is pretty expensive to feed! If your horse is deficient, you may want to consider switching feeds or adding in a supplement depending on the situation.
This nutrient is always on the forefront of my mind when balancing a diet and I am glad it is receiving the recognition it deserves.
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๐๐ฒ ๐ฆ๐๐ข๐ง ๐ญ๐๐ค๐๐๐ฐ๐๐ฒ๐ฌ ๐๐ซ๐:
1๏ธโฃ Make sure you feed a product based on their recommended feeding rate to meet requirements
2๏ธโฃ Blood test to evaluate how your current feed program is working
3๏ธโฃ Donโt just supplement blindly unless you enjoy spending money. Supplementing above requirements is only needed if your horse is deficient.
Cheers!
Dr. DeBoer
Muirhead, TL, Wichtel, JJ, Stryhn, H, McClure, JT. 2010. The selenium and vitamin E status of horses in Prince Edward Island. Can Vet J. 51(9):979-985.
Pitel, MO, EC McKenzie, JL Johns, and RL Stuart. 2020. Influence of specific management practices on blood selenium, vitamin E, and beta-carotene concentrations in horses and risk of nutritional deficiency. Journal of Veterinary Internal Medicine 34:2132-2141.
