Despite a constant decline in grassland areas in the last decades at regional and national scales in France, in particular on lowland dairy cattle areas, grasslands could have been maintained locally. The aim of this paper is to study the reasons of grassland maintenance crossing animal sciences and sociology on the territory (3 case studies) and farm scale (one case study). On the local scale, by looking at the evolution of the agrarian system we identified long-term factors, on local and larger scales, that potentially lead to grassland maintenance. They combined the following: i) a dairy specialisation with a high number of market opportunities, ii) a diversity of advice services on grassland management suited to the diversity of farmer profiles, iii) local public policies and social relations in favour of agriculture and agroecological practices. When this combination occurs, a large diversity of dairy systems with variable grasslands roles exists. On the farm scale, by studying the grassland practices over the long term and the farmers' conceptions of grasslands, we observed that grassland maintenance takes place either through a complete redesign of the fodder system or through the hybridization of practices aimed at obtaining dairy systems that are still intensive but try to be more agri-ecological. The hybridation processes are favoured by i) the coexistence of a strong diversity of forage management practices and ways of thinking the forage production and ii) their interaction in numerous dialogue networks.