The oral Fecal microbiota transplantation (FMT) is preferred in experimental mice. The upper gastrointestinal tract influences microbe selection, though its role is unclear. Our study shows oral fecal gavage (OFG) reduces liver failure severity in mice. We present protocols for preparing the fresh feces for OFG and OPG, revealing OFG recipient gut microbiota evolved rapidly, resembling that of donors by day seven. The colonization of commensal microbes after OFG, with Lactobacillaceae, Akkermansiaceae, and Lachnospiraceae becoming enriched over time.