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Title: Somatotrophic and thyroid hormones around the onset of lay in broiler breeders under different conditions
Authors: Malheiros, RD ×
Moraes, VMB
Furlan, RL
Bruggeman, Veerle
Buyse, Johan
Decuypere, Eddy
Macari, M #
Issue Date: 2002
Publisher: Akademiai kiado
Series Title: Acta veterinaria hungarica vol:50 issue:4 pages:425-434
Abstract: Somatotrophic and thyroid hormones were determined around the onset of reproduction in broiler breeders reared in two different housing systems [dark, close-sided house (CH) and conventional, open-sided house (OH)]. In both groups age-related changes were obvious for thyroxine (T-4), growth hormone (GH) and insulin-like growth factor (IGF-1); levels of T-4 decreased, especially between 24 and 28 weeks in both groups; concomitantly GH sharply increased over the same period. A transient peak in triiodothyronine (T-3) occurred between 25 and 27 weeks. The effect of housing was only present after the onset of lay. Between weeks 27-28 and the end of the period studied, the CH group showed higher levels of GH and T-3 but lower T-4 levels as compared to the OH group. A significant increase in GH after onset of lay, without any significant rise in T-3 or in IGF-I, could point to a relative insensitivity to high plasma GH levels. Changes at GH receptor level, together with an increased pituitary GH secretion and/or decreased GH turnover may be expected. This may indicate that hypothalamo-pituitary changes at the onset of lay not only imply changes of gonadotrophic cell function, but also other hormonal axes. The relatively decrease in T-4 without changes in T-3, may point to a decrease in the activity of the thyrotropic axis.
URI: 
ISSN: 0236-6290
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Division of Livestock-Nutrition-Quality (-)
× corresponding author
# (joint) last author

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