Biotin is a nutritional decisive factor in epithelia formations and annex formations. In poultry meat and egg-production poultry the biotin deficiency  may be primary or secondary. The primary deficiency, is produced by the absence of biotin in feed, is the least common. In contrast secondary deficiency is more common and is due to the greater needs of modern strains or temporary deficiencies in periods of high productivity. Whatever the kind of deficiency is visible with the injury which appears on the image. This deficiency affects the mucous membranes of the organism, making them more permeable to attack by microorganisms.