Ascorbic acid biosynthesis and metabolism in hyperthyroid broiler chickens.

Hyperthyroidism, or an abnormally high metabolism, is a major problem in the poultry industry. Due to a variety of genetic and management (i.e. temperature, overcrowding, etc.) related issues are thought to be responsible for the high incidence of hyperthyroidism in broiler (meat-producing) chickens. Hyperthyroidism is responsible for a number of detrimental health effects in affected animals, including decreased tissue ascorbic acid concentrations, lowered body weight, development of ascites syndrome (the uncontrolled collection of fluid in the body cavity) and even death. This presents a problem from two angles: on the economic side, this is bad because it decreases the amount of meat produced per bird; from a humane standpoint, it is bad because it is the cause of animal suffering. Hyperthyroidism was induced in domestic broiler chickens by addition of a thyroid hormone to the diet. The important antioxidant ascorbic acid, commonly known as vitamin C, was then studied as a dietary supplement to alleviate its negative effects. When compared with control animals, it was discovered that hyperthyroidism was successfully induced in the experimental animals. A strong trend was also noted in which hyperthyroid animals supplemented with dietary ascorbic acid tended to have tissue ascorbic acid concentrations and body weights much closer to control levels than the non-supplemented hyperthyroid chickens.