The goal of this research was to gain understanding of in vitro methane (CH4) production from the cecal contents of White Roman geese under various incubation conditions. Five experiments were conducted to ascertain the effects of i) incubation time, ii) pH, iii) the addition of formic acid to the culture media, iv) temperature, and v) the addition of salt to the nutritive liquid. Methane production increased significantly with the supplementation of formic acid in the culture fluid (Experiment III). Additionally, CH4 production Experiment V was higher than that without saline. In contrast, low CH4 production occurred under acidic conditions (pH ≦5.4) and at temperatures higher or lower than typical bird body temperature (43 °C) without formic acid and saline solution in the culture media. Since bird body temperature cannot be controlled easily, approaches such as maintaining cecum fluid at low pH and preventing the formation of formic acid by adjusting the recipes of feeds could be considered for controlling in vivo CH4 production from the intestinal tract digesta of geese.