Answer
Dark meat has an abundance of slow oxidative (SO) muscle fibers. Dark meat also has more blood vessels, more myoglobin, and more mitochondria ( per muscle cell) than white meat. Greater number of mitochondria enables enhanced generation of ATP. This ability makes these muscle fibers resistant to fatigue and facilitates contracting for several hours without the need to rest.
Work Step by Step
The legs of chicken and ducks are used for walking, and the wings of ducks are used for flying over long distances-- theses are sustained activities. Ducks migrate over very long distances, and can fly more than 250 miles per day. Therefore, they need slow oxidative fibers, Nevertheless, some FOG fibers are also found in dark meat.
FOG fibers have many capillaries and much myoglobin. They use anerobic respiration to generate ATP and confer moderate resistance to fatigue.-- adequate for moderate bursts of movements, the types that ducks and chicken do daily to escape threats.
White meat has mainly fast glycolytic fibers (FG). These fibers have fewer capillaries and less myoglobin . They generate ATP mainly by glycolysis because they have few mitochondria. These fibers are adequate for quick intense anerobic contractions for short periods of time. Therefore, chicken breast muscles enable them to fly short distances to escape danger or predation.
