Acute Decrease in Vitellogenin Synthesis by deprivation of food and Water in Laying Hens.

Abstract

Vitellogenin synthesis during a decrease

Changes in Thyrotropin Messenger RNA and Circulating Hormone Levels during Induced Molting of the Hen (<i>Gallus domesticus</i>)

“…First, gonadotropin and sex steroid levels declined quickly with the cessation of laying as early as Day 1 of the deprivation treatment and remained low during the molting period. Early declines in hormone levels related to egg laying during induced molts of the hen are well documented [2,6], and our results are in line with these reports.…”

“…Due to biological interest as well as economic importance, many studies have been conducted to clarify the hormonal mechanism of induced molting (see [2] for review). Increases in plasma thyroxine (T 4 ) and triiodothyronine (T 3 ) levels during induced molting have been reported [2][3][4][5][6], although these reports differ in the exact time course of the changes. Elevations of T3 and T4 have also been reported in natural seasonal molts of the hen [7] and some wild avian species [8,9].…”

Dietary betaine activates hepatic VTGII expression in laying hens associated with hypomethylation of GR gene promoter and enhanced GR expression

“…Three subtypes of VTGs have been identified in the chicken, among which VTGII is the most abundant [ 4 ]. Sekimoto et al found a close relationship between decreased egg production and lower VTG concentration in laying hens subjected to food and water deprivation [ 5 ]. Liou et al reported a positive correlation between serum level of VTG and total egg production in Taiwan red feathered chickens [ 6 ].…”

Specific Anti-peptide Antibody to &beta; Subunit of Chicken Thyrotropin: Production and Characterization

“…48 : 197-204, 2002) vian thyroid hormones have been reported to affect not only heat production, metabolism and growth as in mammals, but also gonadal development, molting and migration (see [1][2][3] for review). The involvement of thyroid hormones in induced molt of the hen, where hens are forced into molting to improve egg production and egg quality, in particular has attracted the attention of investigators due to its biological interest as well as economic importance to the poultry industry [4][5][6]. Whether the natural seasonal molt is brought about by increased thyroid activity seems less certain, but t h e r e h a v e b e e n r e p o r t s s u g g e s t i n g t h e involvement of the thyroid in wild avian species (see [7] for review).…”