Malheiros R D, Moraes Vera Maria Barbosa, Furlan R L, Bruggeman Veerle, Buyse J, Decuypere E, Macari M
Departamento de Morfologia e Fisiologia Animal, Universidade Estadual Paulista (UNESP), Via de acesso Paulo Donato Castellane s/n, Bairro Rural, Jaboticabal, 14870-000, SP, Brazil.
Acta Vet Hung. 2002;50(4):425-34. doi: 10.1556/AVet.50.2002.4.5.
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 (T4), growth hormone (GH) and insulin-like growth factor (IGF-1); levels of T4 decreased, especially between 24 and 28 weeks in both groups; concomitantly GH sharply increased over the same period. A transient peak in triiodothyronine (T3) 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 T3 but lower T4 levels as compared to the OH group. A significant increase in GH after onset of lay, without any significant rise in T3 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 T4 without changes in T3, may point to a decrease in the activity of the thyrotropic axis.
在两种不同饲养系统（黑暗、封闭鸡舍（CH）和传统、开放式鸡舍（OH））中饲养的肉种鸡繁殖开始前后，对其生长激素和甲状腺激素进行了测定。在两组中，甲状腺素（T4）、生长激素（GH）和胰岛素样生长因子（IGF-1）的年龄相关变化都很明显；T4水平下降，尤其是两组在24至28周之间；同期GH急剧增加。三碘甲状腺原氨酸（T3）在25至27周之间出现短暂峰值。饲养方式的影响仅在产蛋开始后才显现。在第27至28周以及研究期结束时，与OH组相比，CH组的GH和T3水平较高，但T4水平较低。产蛋开始后GH显著增加，而T3或IGF-I没有任何显著升高，这可能表明对高血浆GH水平相对不敏感。预计GH受体水平会发生变化，同时垂体GH分泌增加和/或GH周转率降低。这可能表明产蛋开始时下丘脑-垂体的变化不仅意味着促性腺细胞功能的变化，还意味着其他激素轴的变化。T4相对下降而T3没有变化，可能表明促甲状腺轴的活性降低。
