Fat soluble vitamin. Promotes the proper absorption, transportation and metabolism of calcium and phosphorus. Vitamin D is critical to proper growth. It is fat soluble, so some amounts are stored in the liver and fatty tissues. The 2 major sources of Vitamin D are sunlight and sun cured hay. Supplements are usually required by stabled horses with limited or no time outdoors.
DEFICIENCY: In experimental conditions, Vitamin D deficiency caused reduced growth rate, bone weakness, failure of normal bone calcification, increased bone demineralization, lameness and loss of appetite. Vitamin D deprivation also caused large amounts of calcium to be excreted in the feces.
TOXICITY: Excess Vitamin D causes improper transport of calcium, thus causing calcium deposits in soft tissues. Results in loss of proper joint function, calcification (hardening) of soft tissues and abnormal enlargement of the skull and jaw. Consult your vet before feeding. Ingestion of Wild Jasmine, a noxious weed, produces similar symptoms to Vitamin D toxicity.