Zhu Huanxi, Shao Xibing, Chen Zhe, Wei Chuankun, Lei Mingming, Ying Shijia, Yu Jianning, Shi Zhendan
Laboratory of Animal Improvement and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
Sunlake Swan Farm, Changzhou 213101, China.
Anim Reprod Sci. 2017 May;180:127-136. doi: 10.1016/j.anireprosci.2017.03.009. Epub 2017 Mar 18.
This study was carried out to induce out-of-season breeding, in the summer, and to achieve high reproductive performance using artificial photoperiod manipulation in the long-day breeding Yangzhou goose. Young geese were subject to a two-phase short-to-long (group A) or a three-phase (long-short-long; group B) photoperiod program February through October. Egg-laying was induced to start similarly in both groups in May, increased to a peak level in July, and then decreased gradually through to October. The peak and post-peak laying rates were higher with the three-phase than with the two-phase program. Plasma progesterone concentrations changed similarly in the two groups, increasing from low levels during the pre-lay periods until the peak laying stage, then decreasing with decline in the egg-laying rate. Plasma T3 concentrations increased from the beginning of the experiment to form the first peak under a short photoperiod, declined to a trough at peak lay and then progressively increased to high levels towards the end of the experiment. Plasma T4 concentrations increased throughout the experiment, showing little response to changes in photoperiod. GnIH mRNA expression level in the hypothalamus steadily decreased from high levels under the short photoperiod to a nadir at peak of lay, but was abruptly up-regulated by over a thousand-fold thereafter. This mRNA expression pattern was also shared by GnIHR, VIPR, TRHR, TSH, and PRL genes in the pituitary gland, and to lesser extent, by GnRH, VIP, and TRH genes in the hypothalamus. Pituitary GnRHR mRNA expression levels changed in a similar manner to that of reproductive activities of geese in both groups. FSH beta subunits mRNA expression levels increased to high levels after day 11 of the long photoperiod, and were higher in group B than in group A at peak laying. LH beta gene expression level was similarly upregulated by photoperiod and was higher in group B than in group A when used the multivariable and two-way analyses of variance. Taken together, photoperiod, through regulation of expression of an array of genes in the hypothalamus and pituitary gland, synchronized stimulation and refractoriness of the reproductive system in Yangzhou geese. The higher out-of-season egg laying performance following the three-phase photo-program treatment was mediated by higher FSH beta and LH beta subunit mRNA expression levels.
本研究旨在通过人工光周期调控诱导扬州鹅在夏季进行反季节繁殖，并实现高繁殖性能。2月至10月期间，对雏鹅进行两阶段短到长（A组）或三阶段（长-短-长；B组）的光周期程序处理。两组均于5月开始诱导产蛋，7月产蛋量增至峰值水平，随后逐渐下降至10月。三阶段光周期程序处理组的产蛋高峰期及高峰期后产蛋率高于两阶段光周期程序处理组。两组血浆孕酮浓度变化相似，在产蛋前期从低水平上升至产蛋高峰期，随后随着产蛋率下降而降低。血浆T3浓度从实验开始时升高，在短光周期下形成第一个峰值，在产蛋高峰期降至低谷，然后在实验结束时逐渐升高至高水平。血浆T4浓度在整个实验过程中持续升高，对光周期变化反应较小。下丘脑GnIH mRNA表达水平在短光周期下从高水平稳步下降至产蛋高峰期的最低点，但此后突然上调超过千倍。垂体中的GnIHR、VIPR、TRHR、TSH和PRL基因也呈现这种mRNA表达模式，下丘脑的GnRH、VIP和TRH基因在较小程度上也如此。两组鹅垂体GnRHR mRNA表达水平的变化与繁殖活动相似。长光周期处理11天后，FSHβ亚基mRNA表达水平升高至高水平，产蛋高峰期时B组高于A组。光周期同样上调LHβ基因表达水平，在多变量和双向方差分析中，B组高于A组。综上所述，光周期通过调节下丘脑和垂体中一系列基因的表达，使扬州鹅生殖系统的刺激和不应期同步。三阶段光周期程序处理后更高的反季节产蛋性能是由更高的FSHβ和LHβ亚基mRNA表达水平介导的。
