What is a characteristic of muscle fibers commonly referred to as "white meat" in birds?

Muscle fibers known as "white meat" in birds are characterized by a low level of myoglobin. Myoglobin is a protein found in muscle tissue that binds oxygen and is crucial for aerobic metabolism, which is necessary for endurance and sustained activities. White meat, typically found in the breast muscles of birds like chickens, is adapted for rapid, short bursts of activity rather than endurance.

This lower myoglobin content means that the muscles are not as efficient at using oxygen for energy production compared to "dark meat," which does contain a higher concentration of myoglobin. The reduced myoglobin is an adaptation to the bird's lifestyle, where quick, powerful movements are necessary for activities like flying or evading predators, rather than prolonged exercise. Thus, the defining feature of these muscle fibers is indeed their low myoglobin content.