Changes in the muscle condition of female Zebra Finches Poephila guttata during egg laying and the role of protein storage in bird skeletal muscle

Abstract

Samples of pectoral muscle tissue from Zebra Finches Poephila guttata were taken from birds at various stages of egg laying. As egg laying progressed, there was a significant loss of both water‐soluble and alkali‐soluble proteins. Gel filtration of the water‐soluble proteins showed three peaks, only one of which changed significantly during the laving cycle. This was a high‐molecular‐weight protein that declined in concentration during the period of egg laying. This protein may function as a reserve, enabling female birds to provide amino acids for egg protein production from their muscle tissue without impairing normal muscle function.