Net feed efficiency (NFE) technology is expected to improve the productivity of grazing systems in Australia's southern beef producing regions. The extended time path required for implementation of this genetic technology into commercial herds and the influence of climatic variability on the pasture base are important issues to address in estimating the benefits of this technology at the farm level. NFE also has the potential to impact on the sustainability of the grazing systems in terms of maintaining adequate pasture cover. These issues are investigated by developing a stochastic dynamic simulation model. The bioeconomic model includes pasture, animal production, herd dynamics and economic sub-models. In this paper the model is presented and the implications of the results for adoption of the technology are discussed.