Bear with me, its been a while since I studied chemistry...
2100kg a year is about 5.75kg per day, or 5750g per day. Now, the molecular mass of cabon dioxide is 44.010 g/mole, so that is 130 moles a day. Now, ideal gas formula says that at standard atmospheric temperature and pressure 1 mole is 22.9 liters, so that moose is belching about 3 cubic meters(2988 liters) of gas a day! That is amazing.
It says the equivalent of 2100kg a year of carbon dioxide, which is only 100 kg of methane.
100kg = 274g per day = 17 moles/day or 384 L. That's still a lot though.