Interrelations of Thyroid and Gonad in the Development of Plumage and Other Sex Characters in Brown Leghorn Roosters

Influence of Hypothyroidism on Histophysiology of Feather Development

“…These findings gain support from the works of Schwarz (1931), Chu (1938), Blivaiss (1947) and Voitkevich (1966). Alkaline phosphatase activity, shown to be essential for proper differentiation of down feathers (Hamilton 1965) plays a multifarious role during development and regeneration of definitive feathers (Shah and Menon 1974).…”

“…Administration of thyroxin or its analogues is reported to induce moult in various avian species (Juhn 1963, Voitkevich 1966. Hypothyroidism and athyreosis are known to retard development of body feathers (Schwarz 1931, Chu 1938, Blivaiss 1947, whereas replacement therapy restores the process to normalcy (Voitkevich 1966). Various suggestions as to the mode in which thyroxin initiates moult and influences plumage development have been advanced, including its local stimulatory effects on the papillae (Juhn 1963) and through general physiological changes in the body (Voitkevich 1966).…”

Energetics and Nutrition of Molt

“…But the relationship between feather growth rates and nutritional status of a bird is not an exclusive one, and ptilochronology involves a series of assumptions, the sum of which rarely can be met (Murphy and King 1991c;Murphy 1992; but also see Grubb 1992). Feather growth rates are affected by a variety of factors including age and sex of the bird, season (Pati and Pathak 1986;Linz and Linz 1987;Grubb et al 1991;Murphy and King 1991c), hormonal status of the bird (lapp 1934;Blivaiss 1947;Kobayashi 1958;Pati and Pathak 1986;Peczely 1992), periodicity in follicle sensitivity (Juhn 1963), and repetition of feather loss and regrowth in a follicle (Honda et al 1982). Hormonal status (including receptor numbers and sensitivity) probably is the fundamental cause underlying most of the nonnutritional factors affecting feather growth rates.…”

Avian Physiology

“…[(a) and (b) from Kumaran and Turner, 1949a; (c) from Blivaiss, 1947. ] that structurally this organ has nothing in common with the seminal vesicle of mammals, and he prefers the designation "seminal sac."…”