Suckler cow farms are susceptible to unexpected changes of weather, market or regulation conditions which may threaten farm sustainability. We propose an original framework to gauge the resilience and vulnerability of farm to unexpected changes conditional to optimal adjustments decisions. A dynamic recursive bioeconomic optimisation model is developed with a detailed biotechnical specification providing numerous sources of flexibility. The model is calibrated to represent different systems for Charolais production in France. Validation involved comparing model outcomes to actual farming practices and checking that model sensitivity to changes is consistent. An example of assessment of forage production variation impacts on a farm producing young bulls and grain and forage crops is proposed. This framework can be extended to simulate different kind of changes to help defining mitigation strategies in a changing environment.