Horses need a balanced diet to maintain optimal health. Ensuring adequate intake of vitamins and minerals is important for many physiological and metabolic functions.

However, a diet consisting solely of forage will not provide your horses with all of their daily vitamin and mineral requirements. [1] Even horses on complete feeds and ration balancers can still experience nutrient deficiencies that negatively impact their health.

Deficiencies in essential nutrients can lead to a range of issues, including poor hoof growth, a dull coat, impaired energy metabolism and slow recovery from illness or exercise.

While short-term nutrient deficiencies may only produce subtle symptoms, prolonged deficiencies or imbalances can have more harmful effects. Deficiencies in antioxidant nutrients, such as vitamin E are particularly detrimental, potentially leading to muscle disorders and neurological problems.

Your horse’s daily requirements for vitamins and minerals are determined based on their bodyweight, physiological status, activity level and overall health.

Continue reading to learn more about the top 7 nutritional deficiencies in the equine diet and how to prevent them.

Nutritional Deficiencies in Equine Diets

Vitamins and minerals are micronutrients that horses only require in small amounts, but that are essential for many functions in their bodies. These nutrients play vital roles in maintaining health, growth, reproduction, and performance.

Vitamins are organic compounds that are involved in energy production, immune function, and antioxidant defenses. Some vitamins can be synthesized in the body, but others must be supplied by the horse’s diet. For example, vitamin D is produced in the skin after exposure to UV light, but this endogenous production may not be sufficient to fully meet the horse’s needs. [2]

Minerals are inorganic elements that must be obtained from the diet because they can not be made in the body. Minerals are important for building strong bones and teeth, maintaining electrolyte balance, and as components of various enzymes and hormones.

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Why are Horses At Risk of Nutrient Deficiencies?

Horses are susceptible to vitamin and mineral deficiencies because the amounts of these nutrients in forages and grains are not always sufficient to meet their needs.

Horses in certain geographic regions are prone to deficiencies in trace minerals because the soils in these regions have low mineral levels. Forages that grow in these soils are deficient in trace minerals and do not supply enough of these nutrients to horses. [2]

Horses on hay-only diets are also prone to nutrient deficiencies because several vitamins degrade in grass after it is cut and stored as hay. [2]

Depending on where they live, horses on a hay-only diet may experience deficiencies in: [1][2]

Unless irrigated with incompletely desalinated water, hays and grains are always deficient in sodium and have variable levels of chloride.

Deficiencies of manganese, calcium, phosphorus or magnesium are also possible. Only potassium and iron are always adequate on forage-based diets. [1][33]

Forage Analysis

The best way to determine whether your horse is at risk of certain nutrient deficiencies is to submit a hay sample for analysis. A forage analysis will help you understand the nutritional content of your forage.

A typical forage report will provide values for the energy, protein, fibre, sugar, starch, and mineral concentrations in your horse’s hay. Vitamin analysis may be available for an additional fee at some labs.

By knowing the exact nutritional content of your forage, owners and managers can provide supplements to balance any deficiencies.