Adequate amounts of riboflavin and niacin are required in the diet for pyroxidine to be used nutritionally. It is also believed to interact with iron and many B-complex vitamins. Vitamin C is synthesized in the liver and other body cells. Deficiency of Vitamin C has not been reported in horses, however, supplements may be useful during hot weather and periods of stress, growth and high performance. 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. 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.