gut metagenome Metagenome

Improving the yield of rumen microbial protein (MCP) has significant importance in the promotion of animal performance, and the reduction of protein feed waste. The amount of energy supplied to the microorganisms is an important factor affecting the amount of protein nitrogen incorporated into rumen MCP. Microbiological studies showed that substrate-level phosphoryla¬tion (SLP) and electron transport phosphorylation (ETP) are two major mechanisms of energy generation within microbial cells. However, how the energy and protein levels in the diet impact the energy productivity of ruminal microbiome, and thereafter the rumen MCP yields, have not been known. Here, by the physiological measurement and metagenome shotgun sequencing, we investigated the effects of energy-rich and protein-rich diets on the rumen MCP yields, as well as the SLP and ETP levels of ruminal microbiome. Finally, our results suggested the increase of dietary energy level promote the rumen fermentation and MCP yields by improving the levels of ETP and SLP that is coupled with glucose fermentation in the ruminal microbiome. But, the increase of dietary protein level has no such effects.