Hall George B, Hildenberger Diane, Long Julie A, Diehl Kristen
Animal Biosciences and Biotechnology Laboratory, BARC, ARS, USDA, 10300 Baltimore Ave, BARC-East, Beltsville, MD 20705, United States.
Animal Biosciences and Biotechnology Laboratory, BARC, ARS, USDA, 10300 Baltimore Ave, BARC-East, Beltsville, MD 20705, United States.
Poult Sci. 2025 Jan;104(1):104592. doi: 10.1016/j.psj.2024.104592. Epub 2024 Nov 26.
Low egg-producing turkeys reduce the profitability of a flock by limiting the number of poults that can be hatched. Understanding the biological mechanics behind egg-production rates will greatly benefit the industry. Two lines with vastly different egg production rates are the Ohio State University E line, and its unselected counterpart, the random-bred control one (RBC1). Differences between E Line and RBC1 hens (n = 4 per line) were investigated by measuring egg production traits, ovarian and follicle anatomical characteristics, and gene expression for reproductively important genes within different follicle types. Data were analyzed by an ANOVA mixed model procedure in SAS. The E line hens produced 20% more eggs than the RBC1 hens, even though they had similar numbers of preovulatory follicles in their ovaries. This was accomplished by increasing clutch length and keeping the pause length the same. On the gene expression side small white follicles (SWF) within E line hens had less LHCGR expression which coincided with downregulation of CYP11A1 and CYP17A1. Along with an upregulation of PRLR in small yellow follicles (SYF) which also coincided with downregulation of CYP17A1. In both cases changes in pituitary hormone receptor transcription levels appeared to affect the steroid hormone synthesis pathway. In SWF from E line hens ESR2 was downregulated, however in the large white follicles and selected follicles ESR1 was the estradiol receptor which was downregulated. The similarity in preovulatory numbers suggests that E line hens aren't selecting more follicles to grow, but instead, follicles are growing faster. Based on the gene expression patterns, the reduction of steroid hormone synthesis might hint at the follicles putting more energy into growth and differentiation. At the same time, the decrease in estradiol receptor might limit the negative effects of estradiol on granulosa cells and allow for more rapid growth, suggesting a possible mechanism for the higher egg production trait of the E line.
产蛋量低的火鸡会限制可孵化雏鸡的数量，从而降低鸡群的盈利能力。了解产蛋率背后的生物学机制将使该行业受益匪浅。俄亥俄州立大学E系及其未经过选择的对应品系，即随机繁殖对照品系1（RBC1），是两个产蛋率差异极大的品系。通过测量产蛋性状、卵巢和卵泡解剖特征以及不同卵泡类型中生殖重要基因的表达，研究了E系和RBC1母鸡（每个品系n = 4）之间的差异。数据在SAS中通过方差分析混合模型程序进行分析。E系母鸡产蛋量比RBC1母鸡多20%，尽管它们卵巢中的排卵前卵泡数量相似。这是通过增加产蛋周期长度并保持间歇期长度不变来实现的。在基因表达方面，E系母鸡体内的小白卵泡（SWF）中促黄体生成素/绒毛膜促性腺激素受体（LHCGR）表达较少，这与细胞色素P450 11A1（CYP11A1）和细胞色素P450 17A1（CYP17A1）的下调相一致。同时，小黄卵泡（SYF）中催乳素受体（PRLR）上调，这也与CYP17A1的下调相一致。在这两种情况下，垂体激素受体转录水平的变化似乎影响了类固醇激素合成途径。在E系母鸡的SWF中，雌激素受体2（ESR2）下调，然而在大白卵泡和选定卵泡中，雌激素受体1（ESR1）作为雌二醇受体被下调。排卵前数量的相似性表明，E系母鸡并不是选择更多的卵泡来生长，而是卵泡生长得更快。基于基因表达模式，类固醇激素合成的减少可能暗示卵泡将更多能量投入到生长和分化中。同时，雌二醇受体的减少可能会限制雌二醇对颗粒细胞的负面影响，并允许更快地生长，这表明了E系高产蛋性状的一种可能机制。
