Effect of Season and Thyroidal Activity on the Molt Response to Progesterone in Chickens , ,

THE association of the gonadal hormone progesterone with the phenomenon of molt was reported by Gabuten and Shaffner (1952 Gabuten and Shaffner (1954) who observed that daily injections of progesterone reduced the specific gravity of the treated pullets’ eggs and induced molt. Shaffner (1954 Shaffner (1955), in extending the above observations, reported that progesterone stimulated the feather papilla to form a new feather; and showed that the number of wing primaries molted varied depending on the progesterone level and thyroidal activity. Other reports demonstrating the molting effect caused by progesterone administration have been made by Adams (1955 Adams (1956). Adams (1956) obtained different degrees of molt as a result of intramuscular, pellet and oral administration of progesterone. EXPERIMENTAL New Hampshire pullets in their first year of production were maintained in individual cage egg-laying batteries and fed an all-mash breeder ration. Artificial illumination (ave. 20 ft. candles) was used to provide a minimum of 14 hours . . .