Development of secondary sexual characters in thyroidectomized brown Leghorn hens

Effects of Thyroidectomy on Egg Production, Molt, and Plasma Thyroid Hormone Concentrations of Turkey Hens , ,

“…Thyroidectomy prior to photostimulation prevented the initiation of egg production in lst-yr and recycled hens, whereas thyroidectomy of laying hens resulted in a cessation of production. This supports the observation of Bilezikian et al (1980) and is similar to the response of chickens (Blivaiss, 1947a;Winchester and Scarborough, 1953).…”

Effect of Embryonic Administration of 131I Upon Reproductive Performance of the White Leghorn

“…Symptoms of hypothyroidism were readily apparent in birds that received 25 or 50 [iCi. 131 I at 16 days of incubation as described by Blivaiss (1947) in surgically thyroidectomized chickens and by Winchester et al (1949); Mellen and Wentworth (1962), and Seigel and Mraz (1965) in "radiothyroid-ecrecticized" ones. Smaller thyroids were observed in 6-week-old birds that received 5 or more |JiCi.…”

Current state and updating of heat and moisture production of poultry and their housing systems

“…Molting is a natural process of all birds in an endeavor to renew their feathers (Lucas and Stettenheim, 1972;North, 1984) prior to migration, shorter days, or cooler weather (North, 1984); and is regulated by hormones (Whittow, 1976;Perek et al, 1957;Blivaiss, 1947b;Van der Meulen, 1939). Normally, wild chickens molt once a year and the molt is not associated with the laying cycle (North, 1984).…”

“…The thyrotrophs and thyroid hormones have been reported to promote molting (Whittow, 1976;Blivaiss, 1947b;Van der Meulen (1939), impair egg laying (Zawadowsky and Nesmeyanova, 1937), and increase metabolic activity (Whittow, 1976). Loss of feathers, naturally or artificially, causes an increase in heat production and heat loss (Perek and Sulman, 1945;Hoffman and Shaffner, 1950).…”