The Maraichine is a local cattle breed originating from the Atlantic coastal marshlands. The extensive breeding of these hardy cows respects the ecological and hydrological functioning of wet grasslands. Yet, as these cows are poorly valued by the meat industry, new ways of promoting the breed are to be explored. The research presented here consisted in the implementation of a participatory design approach, using the KCP (Knowledge-Concepts-Proposals) method. This participatory design approach was set up on the basis of a long-standing collaboration between local researchers and farmers, and on a preliminary sociological diagnostic. Four workshops were conducted in 2020-2021, bringing together a total of sixty varied stakeholders: farmers, naturalists, consumers, institutional actors, researchers, meat industry intermediaries, etc. At each stage, the organizers did their best to ensure that the researchintervention approach integrated stakeholders’ divergent views, was co-constructed, and accounted for the Maraichine breeding’s current trajectory. Nevertheless, it raises ethical questions about the position of researchers as well as the involvement of, and appropriation by, stakeholders. This paper presents a reflexive analysis of this collective experience.