Riboflavin was first isolated from egg white and was later isolated from milk and liver. The name was adopted after the compound was shown to contain the sugar alcohol, ribitol. It is very slightly soluble in water at a neutral or acid pH, but is highly soluble in alkaline solution. Riboflavin is synthesized by the gut microflora and, thus, may reduce the dietary need for the vitamin. Riboflavin is present at various concentrations in a wide range of feeds. It is present in significant quantities in fresh pasture but is low in cereals where it is complexed with proteins.
Riboflavin is required in the diets of nonruminant animals. Ruminants obtain sufficient amounts of the vitamin from that synthesized by the rumen micro flora. Deficient intakes of the vitamin result in impaired growth. Chronic riboflavin deficiency can be fatal. Specific signs of riboflavin deficiency include seborrheic dermatitis, cheilosis, conjunctivitis, and congenital malformations in rats and mice; curled toe paralysis, reduced embryonic survival, and dermatitis in poultry; muscular weakness, ataxia, dermatitis, anemia, and cardiological changes in dogs; and dermatitis and normocytic hypochromic anemia in primates.
