Intensive livestock farming is criticised for its environmental impacts, including those on biodiversity. Several prospective studies call for a more plant-based diet for the sake of the environment and human health. This context opens up prospects for extensive herbivore farms that favour biodiversity. This article focuses on three farms of this type, exploring their relationship with living organisms, the challenge of assessing their environmental impacts and the question of support and commitment for this type of farm. These three farms have lower environmental impacts than a typical conventional dairy farm in western France, but are (much) less productive. Transitioning to this type of farming will benefit biodiversity and greatly decrease environmental impacts, provided that it is accompanied by a dietary transition towards less animal protein and more plant protein.