The importance of vitamin H or biotin for animals and birds is undeniable. It plays an essential role in both carbohydrate and lipid metabolism and can also influence protein synthesis via its effects on the nature and formation rate of RNA. Biotin is needed for normal function of the thyroid and adrenal glands, the reproductive tract and the nervous system. Chickens with biotin deficiency are at an increased risk of developing secondary bacterial infections anywhere that their skin is exposed, such as their feet (bumblefoot) and bare patches without feathers (breast blister).
There has also been an association made between biotin deficiency and fatty liver syndrome in laying hens.