Histopathological and biochemical effects of feeding excess dietary methionine to broiler chicks

Three experiments were conducted to determine the histological and biochemical effects of toxic levels of dietary DL-methionine on broiler chicks fed an isolated soy-protein/cornstarch-purified diet containing 20% protein, 0.59% methionine, and 3,304 kilocalories of metabolizable energy per kilogram. An appropriate level of supplementary DL-methionine to use in toxicity studies was found to be 1.5%. It significantly depressed (P less than 0.01) gain in body weight, hematocrit, and hemoglobin concentration, increased (P less than 0.05) the level of iron in liver and spleen, caused pancreatic damage, and induced neurological changes. Unlike the retarded growth and increased iron levels in spleen and liver, the fall in hematocrit and hemoglobin values was independent of the reduction in feed intake caused by excess dietary methionine.