Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742; Animal Biosciences and Biotechnology Laboratory, BARC, ARS, USDA, Beltsville, MD 20705.
Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742.
Poult Sci. 2020 Feb;99(2):1163-1173. doi: 10.1016/j.psj.2019.12.028. Epub 2020 Jan 24.
Variation in egg production exists in commercial turkey hens, with low egg producing hens (LEPH) costing more per egg produced than high egg producing hens (HEPH). Egg production correlates with ovulation frequency, which is governed by the hypothalamic-pituitary-gonadal (HPG) axis. Ovulation is stimulated by a preovulatory surge (PS) of progesterone and luteinizing hormone, triggered by gonadotropin releasing hormone release and inhibited by gonadotropin inhibiting hormone. Differences between LEPH and HEPH were characterized by determining HPG axis plasma hormone profiles and mRNA levels for key genes, both outside and inside of the PS (n = 3 per group). Data were analyzed with a 2-way ANOVA using the mixed models procedure of SAS. In the HPG axis, plasma progesterone levels were not affected by egg production level but were elevated during the PS. In contrast, plasma estradiol levels were higher in HEPH than in LEPH but were not associated with the PS. LEPH exhibited decreased gene expression associated with ovulation stimulation and increased gene expression associated with ovulation inhibition in the hypothalamus and pituitary. In ovarian follicle cells, LEPH displayed decreased gene expression associated with progesterone, androgen, and estradiol production in the F1 follicle granulosa cells, F5 theca interna cells, and small white follicle cells, respectively. Different degrees of stimulation and inhibition within all tissues of the HPG axis were noted between LEPH and HEPH turkey hens, with HEPH showing higher expression of genes related to ovulation and steroidogenesis.
商业火鸡母鸡的产蛋量存在差异，低产蛋母鸡（LEPH）每生产一个鸡蛋的成本高于高产蛋母鸡（HEPH）。产蛋量与排卵频率相关，而排卵频率受下丘脑-垂体-性腺（HPG）轴的控制。排卵受黄体生成素和孕激素的促排卵前激增（PS）刺激，由促性腺激素释放激素释放触发，由促性腺激素抑制激素抑制。通过测定 HPG 轴血浆激素谱和关键基因的 mRNA 水平，对 LEPH 和 HEPH 之间的差异进行了表征，PS 内外（每组 3 个）。使用 SAS 的混合模型程序对数据进行了 2 因素方差分析。在 HPG 轴中，产蛋水平不影响血浆孕激素水平，但在 PS 期间升高。相比之下，HEPH 中的血浆雌二醇水平高于 LEPH，但与 PS 无关。与排卵刺激相关的基因表达在 LEPH 中降低，与排卵抑制相关的基因表达在下丘脑和垂体中增加。在卵巢卵泡细胞中，LEPH 显示与 F1 卵泡颗粒细胞、F5 卵泡内膜细胞和小白卵泡细胞中孕激素、雄激素和雌二醇产生相关的基因表达降低。在 HPG 轴的所有组织中，LEPH 和 HEPH 火鸡母鸡之间都存在不同程度的刺激和抑制，HEPH 显示与排卵和类固醇生成相关的基因表达更高。
