The anaerobic digestion of biomass is a complex, dynamic, and highly nonlinear process. Hence, a mathematical model that is capable of describing the complete operability region with sufficient accuracy cannot be identifiable even with the most advanced process monitoring technology. The complexity of the anaerobic digestion model no. 1 (ADM1) leads to the application of either parameter-reduced versions of the ADM1 or simpler models as, e.g., the anaerobic digestion model AM2. A comparative study for the simulation of biogas formation at dynamic feedstock loading using maize silage was performed with both models.