When new remedies or treatments are considered for used in a farming enterprise the main concern is whether the benefit will outweigh the cost and predicted losses. Benefits however should not only be measured in economic terms. In addition to stochastic partial budget models that estimate cost and benefits when using STARTVAC® (HIPRA) mastitis vaccine, a model was developed to calculate the intramammary infection (IMI) dynamics of Staphylococcus aureus (S. aureus).