The Swiss agricultural sectoral information and forecasting system (SILAS) is based on the PMP standard approach. The marginal cost functions are estimated by exogenous elasticities. Due to the lack of empirical data the elasticities were set for all activities to unity. Based on total milk production costs of FADN farms, regional supply functions were estimated. The results are used to adjust the marginal cost functions of organic and non-organic dairy cow activities in the model SILAS to the empirically estimated functions. The results show that the marginal cost functions in the sectoral model are in general a bit steeper than in the FADN estimations, when elasticities by the value one are applied. Major differences between organic and non-organic milk production could not be observed. Adjusting the slope of the marginal cost functions to the empirically estimated ones leads to slightly different forecast results. Mainly the number of organic cows is higher in the FADN adjusted scenario than in the reference scenario without any adjustments.