Biotin deficiency and the development of the fatty liver and kidney syndrome in chickens: an ultrastructural study.

The structure of the tissue from the liver, kidneys, pancreas and adrenal glands of 4-week-old chickens showing symptoms of the fatty liver and kidney syndrome (FLKS) was compared with that of normal tissue and related to the amount of biotin present in the liver tissue. These birds were reared with different levels of dietary biotin and were stressed by removal of food before being killed. Birds with less than 1-5 microgram biotin/g liver were considered to be deficient in biotin. In the stressed birds the severity of FLKS increased with decreasing levels of biotin. No lesions were found in the liver and kidney tissue of the birds with severe FLKS. Large quantities of fat were accumulated in the hepatocytes and intercellular spaces of the liver tissue, but the cell contents were not disorganized. In the kidney, conspicuous fat accumulation occurred in the proximal convoluted tubule cells and some ultrastructural disorganization of the cell contents was evident. No structural changes were found in the tissue of the pancreas or the adrenal glands of chickens suffering from severe FLKS.