Embodiments herein include a composition that can include a saponin composition including saponins and at least one medium chain fatty acid (MCFA) or ester or salt thereof. In an embodiment, the saponins and at least one MCFA present in the composition can work synergistically to prevent methanogenesis by bacteria. In another embodiment, a method of processing animal feed using the compositions herein is included. Other embodiments are also included herein.