瘤胃微生物蛋白合成过程中伴随着氢的消耗，但是氢介导微生物蛋白合成的具体机制还不清晰。本项目首先通过添加淀粉增强氢供应水平进行体外模拟瘤胃发酵试验，对氨同化过程关键酶、微生物蛋白、氢气、挥发性脂肪酸、微生物群落组成等进行分析，研究增强氢供应水平对微生物蛋白合成的影响，同时利用2H标记的氢气进行同位素示踪试验，精确分析氢向微生物蛋白迁移的过程。其次通过添加铵盐增强氢消耗水平进行体外模拟瘤胃发酵试验，研究提高氢消耗水平对微生物蛋白合成的影响，同时利用15N标记的铵盐进行同位素示踪试验，精确分析氮定向合成微生物蛋白的过程。最后，根据体外试验结果，通过添加淀粉和铵盐设置氢供应与消耗水平，以奶牛为实验动物，研究体内条件下氢代谢介导微生物蛋白合成和提升奶牛生产性能的调控机制。项目旨在研究氢代谢介导微生物蛋白合成的机制，进一步解析瘤胃内氢的生物学功能，为提高家畜氮素利用效率和减少氮排放提供科学支持。

Hydrogen is consumed during rumen microbial protein synthesis, but the mechanism of microbial protein synthesis mediated by hydrogen is not clear. In this project, starch will be used to study the effect of enhanced hydrogen supply on microbial protein synthesis by in vitro batch culture, and the key enzymes of ammonium assimilation, microbial protein, hydrogen, volatile fatty acids and microbial community will be analyzed. At the same time, the 2H-labled hydrogen will be used to perform isotope tracing experiment to accurately analyze the hydrogen migration to microbial protein. Secondly, the ammonium salt will be used to study the effect of enhanced hydrogen consumption on microbial protein by in vitro batch culture, while 15N-labled ammonium salt will be used to perform isotope tracing test to accurately analyze the nitrogen migration to microbial protein synthesis. Finally, the addition levels of starch and ammonium salt filtrated from the in vitro test will be used to set up hydrogen supply and consumption coupled diet for dairy cows feeding experiment, to study the effect of hydrogen metabolism on microbial protein synthesis and production performance under in vivo conditions. This project aims to analyze the mechanism of hydrogen metabolism-mediated microbial protein synthesis and the biological function of hydrogen in rumen, and provide a scientific basis for improving the nitrogen utilization efficiency of livestock and decreasing nitrogen emissions.