The dairy sector in Vietnam quickly evolved with the support of government and private sector, R&D organizations (NIAH, CIRAD, JICA, etc.) and ONG¿s. Dairy farms are actively supported not only in the interest of milk production but also for their socio-economic role. New policies and technology innovations are being proposed in order to answer the main issues related to the socio-economic and environmental sustainability of the dairy sector. The selection of orientations to be implemented requires a comprehensive analysis of their impact and eventual consequences at a multi-scale production level. Modeling appears as an interesting decision tool for the agricultural sector because it helps to assess the complex interactions found in the farm system as well as to analyze the configuration of alternative technical innovations. Moc Chau dairy farmers face important issues related to milk production in which the availability of forage resources during winter season and the high cost of concentrated feeds are presently limiting the dairy herd development and the economic sustainability of farms. In response to these issues, researchers provide alternative solutions using new forage technologies based on temperate species. Oat species proved to be the best solution in terms of agro-ecological adaptation, high production yields, excellent nutritive value and low production costs. The adoption of oat forage by farmers started in 2004 and two years later 30% of total farmers were using this new forage resource in their farming system. The number of farmers implicated in oat production and the surface of land allocated are considered useful indicators of farmer adoption. However, some dissatisfaction opinions related to oat potentialities were addressed which may possibly influence further adoption. In order to realize the importance of these factors we developed a multi-period farm-scale model. Four criterions were chosen to establish the farm typology (soil fertility,