Why do turkeys have dark and white meat?

     In a turkey the active muscles such as the legs store a lot of oxygen and become dark, while less active muscles like the breast remain white.

Turkeys can fly short distances -- typically from ground to perch -- but they are not known for their sustained flighing abilities. They rely on their legs to get them around. The active muscles, such as the legs and thighs, are full of blood vessels. These blood vessels contain myoglobin (or muscle hemoglobin), which delivers oxygen to the muscles. The more myoglobin the muscles contain, the darker the muscle.

Scientists often refer to these active muscles as slow-twitch fibers. Slow-twitch fibers are built for endurance, which allows the muscles to work for long periods of time. Thus the turkey can run around all day without getting tired.

On the other hand, white meat is the result of well-rested muscles. The breast muscles, which are used for flying, are hardly used by turkeys. There is no need to have a rich supply of oxygen delivered to these muscles. Scientists refer to these types of muscles as fast-twitch fibers. Fast-twitch fibers are designed for quick bursts of energy, but they fatigue quickly. In addition, fast twitch muscles are fueled by glycogen (carbohydrate stored in body tissues) giving the muscles that immediate explosion of energy needed to move rapidly.

Related Web Sites

The Accidental Scientist: Science of Cooking - What gives meat its color? - A brief explanation of what gives meat its color. The Accidental Scientist: Science of Cooking: Comparative Muscle Chart - A visual description of the slow and fast twitch muscles found in humans and various animals. BBC Science and Nature: Muscles- Fast and Slow Twitch - A brief explanation of the two types of muscle fiber: fast and slow twitch. An interactive body game is also provided U.S. Census Bureau - Facts_for_Features, Thanksgiving 2009. (PDF 63.7 KB) - All sorts of facts about Thanksgiving, such as number of turkeys raised in the United States, can be found here. Turkey for the Holidays - Everything you wanted to know about turkey, such as nutrition, safety, facts, history and lore, can be found on this Web site from the University of Illinois Extension Service.

Further Reading

Davis, Karen. More than a meal: the turkey in history, myth, ritual, and reality. New York, Lantern Books, c2001. 192 p. Grivetti, Louis E, Jan L. Corlett, and Cassius T. Lockett. Food in American history part 2: turkey, in Nutrition today, v. 36, March 2001: pg.88-96. Haseltine, Eric. The body electric: measuring your fast-twitch and slow-twitch fibres, in Discover, v. 22, Dec., 2001: pg. 92. Martini, Frederic. Muscle tissue, in Fundamentals of anatomy and physiology. Upper Saddle River, NJ, Prentice Hall, c1998. pg 276-313. (Slow and Fast Fibers, p. 302)Bibliography item 1. McGinty, Brian. The American turkey, in Early American life, v. 9, 1978: 24-26, 76-77. Vogel, Steven. Prime mover: a natural history of muscle. New York, W.W. Norton & Company, c2001. 370 p.

For more print resources...
Search on "cookery (turkey)," "meat," "muscles," or "turkey" in the Library of Congress Online Catalog.

Releasing a translocated Wild Turkey into its new home in Everglades National Park.

Photo: Wild Turkey. From Birds, on
the Zion National Park Web site.

Photo: The First Small Turkey - Technologies in the Marketplace, USDA Agricultural Research Service.

Election cartoon - Whig candidate Winfield Scott & Democrat Franklin Pierce. Prints & Photographs Division, Library of Congress.

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