Vitamin A

Sources

Most of a horse's vitamin A comes from beta-carotene, found in fresh green forage, good hay, maize and carrots ^[1]. Beta-carotene declines in stored forage, and hay stored for over a year may not supply enough; horses on conserved forage without grazing are at risk ^[1].

Deficiency

Signs include night blindness, impaired growth and impaired blood cell formation, although deficiency is uncommon ^[1].

Toxicity

Prolonged intakes of more than 10 times the recommended amount can cause bone fragility, bony growths, skin lesions and birth defects. No toxicity is known from beta-carotene ^[1].

Reading it on a label

For the horse, 1 mg of beta-carotene equals 400 IU of active vitamin A ^[1].

See also reading feed labels.