It is tough to study a wide ranging and dangerous animal such as bison. However, studies done on buffalo relative to cattle showed that on a similar diet they produced similar amounts of methane.

The two key differences between current production cattle and bison comes down to grazing and density differences. Nature does not naturally support the cattle density we have due to feedlots. Bison when grazing don’t chew grasses down as low as cattle, which is better for grassland ecosystems and bison roam further allowing land to rest.

If we replaced all cattle production with cellular ag and repopulated bison it would be better for ecosystems and methane emissions.

The reality is that ability to actually do this is decades upon decades away and will be very costly.