Effect of Photoperiod on the Egg Production, Plasma Luteinizing Hormone, Follicle-Stimulating Hormone, Gonadal Hormones, and Mrna Levels of Lh and Fsh in the Hypothalamic-Pituitary-Gonadal Axis of Pigeons

ABSTRACT We investigated the egg production, changes in luteinizing hormone (LH), follicle-stimulating hormone (FSH), gonadal hormones, and their mRNA levels in the hypothalamic-pituitary-gonadal axis of White King pigeons submitted to different photoperiods. The treatments consisted of three photoperiods (8 h light (L):16 h dark (D), 12L:12D, and 16L:8D), with three replicates of twelve pairs of adult pigeons. The birds were exposed the photoperiods for 45 days. Egg production performance was recorded daily. Six pigeon pairs per replicate were selected for plasma collection, and six pigeon pairs per replicate for the resection of the hypothalamic-pituitary-gonadal (HPG) axis. Egg production was significantly improved by long-day lighting (16L:8D), while no differences in egg shape index were detected. Higher average egg weight was obtained in 16L:8D group, whereas broken egg percentage was higher in the 8L:16D group. Female LH level was significantly higher in long-day lighting, and the FSH level significantly lower in short-day lighting. The females in the 16L:8D group had higher estrogen level. The photoperiods had a minor effect on plasma LH and testosterone in males, whereas the FSH level was significantly higher in the 16L:8D group. The level of LH mRNA expression was higher in both females and males of the 16L:8D group. Similar trends in FSH mRNA expression observed in both females and males. The 16L:8D photoperiod not only improved egg production, but also stimulated plasma LH, FSH, gonadal hormones, and promoted LH and FSH mRNA expression in pigeons.

摘要
本研究探究了不同光周期处理下白羽王鸽下丘脑-垂体-性腺轴（hypothalamic-pituitary-gonadal axis，HPG轴）的产蛋性能、促黄体生成素（luteinizing hormone, LH）、促卵泡生成素（follicle-stimulating hormone, FSH）、性腺激素的变化及其mRNA表达水平。实验设置三种光周期处理（8小时光照(L):16小时黑暗(D)、12L:12D、16L:8D），每组设置3个重复，每个重复包含12对成年鸽。受试鸽接受对应光周期处理共计45天，每日记录产蛋性能。每个重复选取6对鸽子采集血浆，另选取6对鸽子进行下丘脑-垂体-性腺轴的解剖摘取。
长日照光照（16L:8D）可显著提升鸽的产蛋性能，而各组蛋形指数无显著差异。16L:8D组的平均蛋重更高，而8L:16D组的破蛋率更高。雌性个体的LH水平在长日照光照下显著升高，短日照光照下FSH水平显著降低。16L:8D组的雌性个体雌激素水平更高。光周期对雄性个体的血浆LH和睾酮水平影响较小，但16L:8D组的FSH水平显著升高。16L:8D组的雌雄个体LH mRNA表达水平均显著升高，雌雄个体的FSH mRNA表达呈现相似趋势。综上，16L:8D光周期不仅可提升鸽的产蛋性能，还可刺激血浆LH、FSH及性腺激素水平，并促进鸽体内LH与FSH的mRNA表达。