Mechanism of Molting in the Hen

Abstract

MOLTING is associated with low laying activity or complete cessation of ovulation, a fact of both endocrinological and economical interest. It is well known that the administration of thyroid substance induces molting in any season of the year in domestic fowl (Torrey and Horning, 1922; Zavadovsky, 1925; Cole and Hutt, 1928; Van der Meulen, 1939; and others). Some investigators reported that histological examination revealed an activation of thyroidal function during molting in several species of birds, e.g. in the pigeon (Elterich, 1936), and in the canary (Takewaki and Mori, 1944). So the assumption has generally been accepted that annual molt is caused by increased thyroid activity of the birds. Sulman and Perek (1947) showed, however, that thiouracil feeding precipitated molting in the hen. Recently Shaffner (1954 Recently Shaffner (1955) and Adams (1955) reported that the administration of a large amount of progesterone induced molting outside the normal molting season. These findings throw . . .