In the mountainous region of North Vietnam, the recent redistribution of the lands and the privatization of the livestock leaded to the intensive culture of the slopes and to a consequent increase of the cattle number. The current agro-sylvo-pastoral systems are characterized by a low sustainability (high erosion and fertility loses of the soils). The forage system is based on the crop residues and natural resources (forest and slope pastures). The research demonstrated that conservation agriculture practices enable the amelioration of the sustainability of those systems in North of Vietnam. Can these agroecological options adapted to the diversity of farms also ameliorate the forage supplies? We propose to design with the farmers of Ði¿n Biên Province (Vietnam) different scenarios of amelioration of the forage production in accord with conservation agriculture and to assess their effect by using a tool to model the mixed farm and the practices of agriculture and forage production from the adaptation of the modeling tool Cikeda. The scenario designed are (S1) implementation of a Pennisetum purpureum (elephant grass) crop, (S2) intensification (fertilization and irrigation) of the Pennisetum purpureum crop, (S3) substitution of the Pennisetum purpureum crop by Panicum maximum (Guinea grass) and (S4) implementation of a Stylosanthès guianensis crop after the 2nd cycle of the rice. The results of the simulation show that if the first scenario is the one with the less technical-economic constraints, the implementation of a Panicum maximum crop could be a solution to face up the forage deficit at the end of the dry season. Moreover, the repartition of the production along the year could be strengthen by the development of report practice (ensilage, hay). The intensification of the forage production is the best solution that permit to fulfill the forage deficiency of the end of the dry season, but it is necessary today to support the farmers to set-up more adapted solutio