Feeding fat-soluble vitamins (A, D, E, and K) along with dietary fat can enhance their absorption and retention in horses. These vitamins are absorbed in the small intestine alongside dietary fat, and sufficient fat in the diet ensures they are effectively utilized by the body.
1. How Fat Improves Absorption
Absorption Mechanism:
- Fat-soluble vitamins dissolve in fat and are incorporated into micelles (tiny fat droplets) in the small intestine.
- These micelles are absorbed through the intestinal lining into the bloodstream.
Fat as a Carrier:
- Without adequate dietary fat, the formation of micelles is inefficient, reducing the absorption of these vitamins.
Improved Retention:
- Dietary fat not only aids absorption but also supports the transport and storage of fat-soluble vitamins in the liver and fat tissues for later use.
2. Dietary Fat Sources for Horses
Horses naturally consume low-fat diets, but small amounts of fat can be added to support vitamin absorption. Common fat sources include:
- Vegetable oils (e.g., soybean, canola, flaxseed oil)
- Rice bran
- Flaxseed or chia seeds
- Commercial high-fat feeds
- High fat ration balancer supplements
3. Considerations When Supplementing
Amount of Fat:
- Horses generally require only small amounts of fat (5-10% of total dietary intake) for this purpose.
- Even a tablespoon of oil can be sufficient to aid absorption of fat-soluble vitamins. Avoid corn oil since it has been linked to inflammation in horses.
- Read labels and follow all feeding directions on supplements.
4. Balanced Diet:
- Work with an equine nutritionist or vet to ensure the overall diet is balanced with forage, concentrates, and necessary supplements.
- Avoid over-supplementation of fat-soluble vitamins, as excess amounts cause horses to back off feed and can accumulate to toxic levels (especially vitamins A and D).
5. Specific Scenarios:
- Pasture-based diets usually provide adequate omega-3 fats from fresh grass and fresh forages have higher vitamin levels. Like people, horses spending adequate time in the sun can convert Vitamin D during grazing season too. If pasture quality and quantity are maintained through the growing season fat-soluble vitamins do not usually need to be supplemented.
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In winter diets with dry hay, the majority of fat is omega-6 and in much less supply. Most of the fat-soluble vitamins are lost in the curing process of hay, therefore, feeding a high-quality, well-fortified feed in adequate amounts is important to ensure nutritional needs are met. Alternately, provide a
supplement that combines added fat with the vitamins and minerals that are lacking in hay. Learn more about feeding hay diets here.
- Horses on low-fat diets, such as those consuming only hay or low-fat grain, may particularly benefit from added fat if fat-soluble vitamin supplements are being provided.
- Heavy or metabolic horses and ponies receiving less than the recommended amount of grain to avoid over-conditioning should be provided balancers and/or other adequate supplements to ensure they have good nutrition without extra calories or starch.
Adding dietary fat when feeding fat-soluble vitamin supplements improves absorption and ensures the horse can fully benefit from these nutrients. This is particularly important for horses on hay-based diets or receiving concentrated vitamin supplementation. Always consult with an equine nutritionist or veterinarian to tailor the diet to your horse’s specific needs.
