资料显示，对产后奶牛和育肥期牛羊饲喂精料水平逐步提高的日粮，有利于瘤胃上皮适应高精料日粮，进而降低瘤胃酸中毒的发病风险，但涉及该过程的生物学机制尚不清楚，推测与高营养水平日粮激活胰岛素样生长因子1（IGF-1）信号通路，进而促进瘤胃上皮生长、加快瘤胃内短链脂肪酸吸收有关，但具体机理不明。本项目拟采用动物试验，结合体外细胞培养模型；研究提高日粮精料水平对IGF-1信号通路中关键因子IGF-1内分泌及其生物活性的影响、对瘤胃上皮细胞IGF-1受体和受体后信号转导通路中关键蛋白的影响与机制，探讨IGF-1受体后通路活化对瘤胃上皮细胞周期、细胞周期蛋白与凋亡相关蛋白的表达和功能的调节及其作用机理。研究结果可揭示“日粮→IGF-1→IGF-1受体→IGF-1受体后通路→瘤胃上皮细胞增殖与凋亡→瘤胃上皮生长”通路。项目将从分子水平阐明瘤胃上皮对高精料日粮的适应机制，为预防瘤胃酸中毒提供新的理论依据。

The previous studies showed that the gradually increasing the amount of concentrate could increase the adaptation of rumen epithelium to high concentrate diet in postpartum cows and feedlot and ovine, and this may have a positive effect on reducing the risk of rumen acidosis, however, the mechanism underling the adaption of rumen epithelium to high concentrate diets is still unclear. It is speculated that mechanisms responsible for the adaption of rumen epithelium to high concentrate diets might be related with the stimulation of ruminal epithelium growth by the activation of insulin-like growth factor 1 (IGF-1) signaling pathway, which was caused by high concentrate feeding, and thereby increase the absorption of short chain fatty acid, however, this speculation requires further examination. This project aims to investigate the effect of the different proportion of concentrate on the changes in IGF-1 secretion and its biological effect, and the mRNA and protein expressions of IGF-1 receptor and the key protein involved in activation of IGF-1 receptor signaling pathway; and to investigate the modulation effect of activation of IGF-1 receptor signaling pathway on the changes in the cell cycle and the expression of the cyclin and apoptosis protein and its mechanisms, using an animal experimental model and the culture cells methods of rumen epithelium in vitro. The success of the project will help reveal the molecular adaptation mechanism of ruminal epithelium to high concentrate, and provide some new ideas and theoretical basis for preventing the rumen acidosis.