The objective of the study was to evaluate over 2017-2020 the grassland production and the profile of the cattle diet in a mixed crop-dairy system named OasYs. Conducted without irrigation and with limited inputs, it was designed with an agroecological approach to permit farmers to live from their dairy system in a context of climate change, while preserving environment and contributing to animal welfare. The forage system is based on multispecies grasslands and on the grazing of several forage resources. Grasslands are diversified in terms of composition (mixtures of different species and cultivars), management (from 100% grazed to 100% cut) and age (1 to 5 years). Their yields ranged from 2.2 to 12.9 t DM/ha/year and were greater i/for cut versus grazed and cut grasslands and ii/ for grasslands containing chicory. Over 2017-2020, herbage (grazed and conserved) represented 28 to 100 % of the monthly diet of the dairy herd. Other forages were grazed fodder beet or other grazed crops and silages of sorghum, maize or of cereal-legumes mixtures. This diversification allowed the system nearly reaching self-sufficiency in forages and in protein.