A simulation model representing the dynamics of a sow farm is presented in contrast with other modelling approaches. To highlight relevant aspects of the model a real application for comparing two different groups of sows is considered. The main contribution of the model is that it is flexible to represent different sow herd management alternatives through an extensive number of input parameters. This features allow to measure the productivity of sows under different set of parameters and performing virtual experimentation. The example presented here is related to estimate economic performances of two phenotypes of sows from a real experiment. Phenotypes consist of sows resistant to a common disease (porcine reproductive and respiratory syndrome) with respect another group sensitive to the same reproductive disease. Furthermore, the implementation in Extend performs efficiently additional calculations to enlarge the understanding of the productive behavior in each case.