Interrelationship amongst the avian orders Galliformes, Columbiformes, and Anseriformes as evinced by the fiber types in the pectoralis muscle

Abstract

The three types of fiber red, white, and intermediate have been characterized from a study of the pectoralis muscle of some representative species of birds of the orders Galliformes, Columbiformes, and Anseriformes. The presence of all the three types was characteristic of the Galliformes except for the Japanese quail, which had only two types, red and white, the former predominating. All the columbiform and anseriform birds studied had similar fiber composition as the Japanese quail. It is postulated that these three orders of birds are closely related phylogenetically.The small red fibers which are known to be adapted for aerobic metabolism metabolizing fat as the main fuel for energy indulge in sustained flight activity whereas the large white fibers, which are adapted for anaerobic metabolism utilizing glycogen, are responsible for quick and short-term activity as in takeoff and in manoeuvring quick and sudden turns while in flight. In the heaviest birds such as the Canada geese, which have a heavy load to lift in the takeoff and also to keep afloat while in the air, were found to possess the largest white and red fibers.