Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB, Canada, T6G 2P5.
Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB, Canada, T6G 2P5; Agriculture and Agri-Food Canada, Edmonton, AB, Canada.
Poult Sci. 2020 Apr;99(4):2215-2229. doi: 10.1016/j.psj.2019.11.065. Epub 2020 Feb 28.
The effect of ME intake (MEI) on the reproductive system was evaluated. Ross 308 broiler breeder pullets (n = 140) were assigned to 2 treatments from 22 to 26 wk of age: (1) Low-energy diet fed restricted (2,807 kcal/kg, low MEI) and (2) high-energy diet fed unrestricted (3,109 kcal/kg, high MEI). Daylength was increased from 8 to 14 h at 22 wk of age with a light intensity of 30 lux. Daily palpation was used to detect sexual maturity via the presence of a hard-shelled egg in the shell gland. Expression of gonadotropin releasing hormone-I (GnRH) and gonadotropin inhibitory hormone (GnIH) genes in the hypothalamus and GnRH receptor (GnRH-RI) and GnIH receptor (GnIH-R) genes in the anterior pituitary gland of each pullet was evaluated from 22 to 26 wk of age using quantitative real time-PCR. Blood samples were taken weekly and luteinizing hormone (LH), follicle stimulating-hormone (FSH), and 17-beta-estradiol (E2) determined using commercial ELISA kits. Carcass samples were used for determination of CP and fat content. Data were analyzed using the MIXED procedure in SAS, and differences were reported where P ≤ 0.05. High MEI treatment pullets had 2.3-fold higher GnRH and 1.8-fold higher GnRH-RI mRNA levels than low MEI pullets. MEI affected neither expression of GnIH and GnIH-R nor carcass protein content. For high MEI (489 kcal/D) and low MEI treatments (258 kcal/D), respectively, from 22 to 26 wk of age (P ≤ 0.05), LH concentration was 3.05 and 1.60 ng/mL; FSH concentration was 145 and 89.3 pg/mL; E2 concentration was 429 and 266 pg/mL, and carcass lipid was 13.9 and 10.3%. The onset of lay for pullets in the high MEI treatment advanced such that 100% had laid by 26 wk of age compared with 30% in the low MEI treatment. We concluded that higher MEI advanced the activation of the hypothalamic-pituitary-gonadal axis and also increased body lipid deposition, and moreover, stimulated reproductive hormone levels which overall accelerated puberty in broiler breeder pullets.
评估了 ME 摄入 (MEI) 对生殖系统的影响。从 22 到 26 周龄，将 140 只罗斯 308 种肉鸡种母鸡分为 2 种处理：（1）低能量饮食限制饲喂（2807kcal/kg，低 MEI）和（2）高能量饮食自由饲喂（3109kcal/kg，高 MEI）。在 22 周龄时，通过增加光照强度至 30lux 将日长从 8 小时延长至 14 小时。通过检查输卵管中是否有硬壳蛋来确定母鸡的性成熟度。使用实时定量 PCR 从 22 到 26 周龄评估每只种母鸡下丘脑促性腺激素释放激素-I (GnRH) 和促性腺激素抑制激素 (GnIH) 基因以及垂体前叶 GnRH 受体 (GnRH-RI) 和 GnIH 受体 (GnIH-R) 基因的表达。每周采集血液样本，并使用商业 ELISA 试剂盒测定促黄体生成素 (LH)、卵泡刺激素 (FSH) 和 17-β-雌二醇 (E2)。使用胴体样本测定 CP 和脂肪含量。使用 SAS 的 MIXED 过程分析数据，当 P≤0.05 时报告差异。高 MEI 处理组的 GnRH 和 GnRH-RI mRNA 水平比低 MEI 组高 2.3 倍和 1.8 倍。MEI 既不影响 GnIH 和 GnIH-R 的表达，也不影响胴体蛋白质含量。在 22 到 26 周龄时（P≤0.05），高 MEI（489kcal/D）和低 MEI（258kcal/D）处理组分别为 LH 浓度为 3.05 和 1.60ng/mL；FSH 浓度为 145 和 89.3pg/mL；E2 浓度为 429 和 266pg/mL，胴体脂肪含量为 13.9 和 10.3%。高 MEI 处理组母鸡的产蛋时间提前，26 周龄时 100%的母鸡已经产蛋，而低 MEI 处理组只有 30%。我们得出结论，较高的 MEI 提前激活了下丘脑-垂体-性腺轴，并增加了身体脂肪沉积，并且还刺激了生殖激素水平，这总体上加速了肉鸡种母鸡的青春期。
