瘤胃菌液移植重塑发生SARA后的奶牛瘤胃稳态的机制研究

Rumen homeostasis refers to the relatively stable state between the ruminal microbiota and the rumen epithelial barrier. Our previous studies found that subacute rumen acidosis (SARA) induced the disorder of rumen microbiota structure and metabolic function and injured the function of rumen epithelial barrier in dairy cattle, resulting in rumen homeostatic imbalance and damage to the rumen health and milk production. Data from practice showed that rumen transfaunation could quickly recover the function of rumen and milk production in dairy cows with SARA, but the underlying mechanism is unknown, presumably related to the remodelling of rumen homeostasis in dairy cattle. Based on these previous findings, this project will carry out the SARA induced experiment and rumen transfaunation experiment, and will use multi-omics technology: 1. To explore the changes in the diversity, composition, structure and function of rumen microbiota after rumen transfaunation, and to clarify the key microbial factors that lead to rumen homeostasis in the dairy cow after SARA; 2. To study the effect of rumen transfaunation on rumen metabolism and its underlying mechanism, and to clarify the relationship between the alternation of rumen microbiota and rumen metabolism remodeling in the dairy cow after SARA; 3, To investigate the mechanism of rumen transfaunation on remodeling ruminal epithelial barrier structure and function and its molecular pathways. In general, the finding of this project is expected to produce original innovation in the understanding of the basic theory of rumen metabolism regulation in dairy cattle, and also has an important role in improving dairy cattle healthiness.

瘤胃稳态是指瘤胃微生态和瘤胃上皮屏障相互作用所构成的动态平衡状态。申请人前期发现，亚急性瘤胃酸中毒（SARA）诱发奶牛瘤胃菌群结构紊乱，瘤胃上皮屏障功能受损，导致瘤胃稳态失衡，引起奶牛生产性能下降；牧场生产实践显示，瘤胃菌液移植可快速恢复发生SARA后的奶牛瘤胃功能与生产性能，但机制不明，推测与瘤胃菌液移植重塑了奶牛瘤胃稳态有关。项目拟在此基础上，通过诱导奶牛SARA试验和瘤胃菌液移植试验，应用多组学联合技术：1、研究瘤胃菌液移植后奶牛瘤胃菌群组成、结构及功能的变化规律，明确促进SARA后奶牛瘤胃稳态重塑的关键微生物因子；2、研究瘤胃菌液移植对SARA后奶牛瘤胃代谢的影响及其机制，阐明瘤胃菌群演变与瘤胃代谢重构间的内在关联机制；3、解析瘤胃菌液移植重塑SARA后奶牛瘤胃上皮屏障结构与功能的机理及分子通路。课题有望在奶牛瘤胃调控基础理论方面产生原始性创新，并对奶牛健康养殖有重要指导意义。

瘤胃稳态是指瘤胃微生态和瘤胃上皮屏障相互作用所构成的动态平衡状态。申请人前期发现，亚急性瘤胃酸中毒（SARA）诱发奶牛瘤胃菌群结构紊乱，瘤胃上皮屏障功能受损，导致瘤胃稳态失衡，引起奶牛生产性能下降；牧场生产实践显示，瘤胃菌液移植可快速恢复发生SARA后的奶牛瘤胃功能与生产性能，但机制不明，推测与瘤胃菌液移植重塑了奶牛瘤胃稳态有关。在前期工作基础上，本项目以高谷物日粮诱导的SARA泌乳奶牛为动物模型，应用宏基因组学、转录组学、16SrRNA基因测序和代谢组学等技术，系统地探究了SARA对奶牛瘤胃稳态的影响以及瘤胃菌液移植对奶牛瘤胃稳态重塑的微生物学机制。结果发现，高谷物日粮导致瘤胃内乙酸生成减少，丙酸、戊酸和总VFA生成增加，诱发SARA，SARA状态下，奶牛瘤胃菌群结构和功能发生改变，瘤胃上皮形态、结构和功能受损，表现出瘤胃上皮乳头变黑增厚，上皮边缘损伤，瘤胃上皮胆固醇合成相关基因表达上调，瘤胃上皮发生炎症反应，最终导致瘤胃稳态失衡。在此基础上，发现通过瘤胃菌液移植有助于重建发生SARA后奶牛的瘤胃菌群稳态，恢复瘤胃发酵和瘤胃上皮形态结构，提高瘤胃植物性多糖和淀粉的降解、氨糖和核苷酸代谢、以及嘌呤代谢；发现经瘤胃菌液移植的奶牛的瘤胃发酵参数的恢复要比瘤胃菌群结构的恢复慢1-2天，瘤胃上皮结构的恢复时间要比瘤胃发酵参数的恢复慢1周左右；但瘤胃菌液移植不能促进瘤胃上皮功能的恢复。项目研究结果阐明了高谷物日粮对奶牛瘤胃稳态的破坏机制，揭示了瘤胃菌液移植重塑奶牛瘤胃稳态的机理，对研发奶牛瘤胃稳态的营养调控策略具有重要指导意义。