Outside the grazing season, vitamin E is a good supplement for all horses
Vitamin E, or alpha-tocopherol, is one of the fat-soluble vitamins essential for the horse’s body. Vitamin E functions as an antioxidant, protecting body cells and fatty acids from the harmful effects of free radicals produced during metabolism. Vitamin E is the only fat-soluble vitamin with direct antioxidant protective effects in the body.
Free radicals enter body tissues through breathing air and normal metabolic processes. Their formation cannot be prevented. They are also part of the immune defence, as they destroy harmful bacteria. Problems arise when there are too many free radicals and the body cannot repair the damage they cause efficiently. Free radicals oxidise body cells in the same way they cause iron to rust.
A horse’s musculature develops through appropriate workload. During prolonged and demanding exertion, free radicals are formed in the muscles. These chemical compounds can damage and destroy muscle cells if they are not neutralised by antioxidants. Harmful muscle cell breakdown can be detected in blood values as elevated muscle enzyme levels. Increased lactic acid levels in muscles can lead to muscle fatigue, stiffness, and other muscle problems.
Vitamin E from the diet
Horses cannot synthesise vitamin E themselves and must obtain it from their diet. Vitamin E requirements vary between individual horses and depend on factors such as size, workload, work intensity, and geographic location. A high oil content in the diet also increases vitamin E requirements. Feeding recommendations vary, but current rules of thumb suggest approximately 750–1000 mg per day for leisure horses and up to 1000–3000 mg per day for competition horses. Breeding animals, as well as mares during pregnancy and lactation, also have a higher-than-normal need for vitamin E.
In nature, horses obtain vitamin E from pasture grass and other green plants. Horses can store a certain amount of vitamin E in their bodies for winter, but if the grazing season is short, this should be taken into account in feeding. If a horse does not graze at all, vitamin E must be provided year-round through other dietary sources.
Deficiency symptoms
Vitamin E deficiency in horses is often difficult to detect, but it may be associated with reduced immune defence, muscle and performance issues, neurological problems such as impaired balance or coordination, reproductive problems such as poor fertility or low-quality semen, and an increased risk of muscle damage, tears, or retinal damage. Other symptoms include anaemia, fatigue, muscle weakness, and muscle stiffness. Symptoms typically appear in late winter, as vitamin E content in hay decreases over time. As a result, hay contains less vitamin E in late winter than freshly harvested hay. For this reason, ensuring adequate vitamin E intake is especially important in late winter and early spring.
How does vitamin E work?
Vitamin E supports muscle and skeletal health during exertion and is therefore an important supplement for horses in hard training and for competition horses. Adequate vitamin E intake promotes better muscle growth and development, helps prevent muscle damage, and supports faster recovery after intense exercise.
Eight different forms of vitamin E are known, of which d-alpha-tocopherol is the most biologically active and best absorbed from the diet. In supplements, natural vitamin E is marked with the abbreviation RRR. Natural vitamin C enhances the antioxidant effects of vitamin E.
Various plant oils are good sources of vitamin E. Whole grains and nuts (such as Brazil nuts) also contain vitamin E.
