Beyond the evidence that a decrease in animal production can limit its environmental footprint, livestock farming systems (LFS) deliver a number of benefits to society, and have feedbacks on cropland production as they influence land productivity by providing manure. We analyse what five options for livestock production and feed use offer for meat and milk production, manure production, cultural ecosystem services (ES), biodiversity conservation, and net greenhouse gas (GHG) emissions from agroecosystems. In line with the CICES classification, we distinguished the cultural ES provided by grassland-based agroecosystems (watching plants and animals, using nature to de-stress) from the conservation of ‘undisturbed’ natural ecosystems as refuge for biodiversity. Sustainable intensification is an efficiency-oriented option that aims to increase the productivity of agricultural land to limit further loss of undisturbed ecosystems. It could maintain animal protein consumption while preserving biodiversity, but provides a low level of cultural services as the share of permanent grasslands in LFS is limited by their lower productivity compared to crops and leys. This option has the lowest potential for net GHG emissions from agriculture, but C is stored in spared land outside the agroecosystems. Three agroecological options aim to limit LFS dependence on chemical inputs and attenuate feed-food competition. First, feeding herbivores on grass-based diets, and monogastric animals on industry/cropland by-products and food-waste resources, values non-edible feedstuffs while providing animal proteins to humans. Recreational services are high thanks to the central role of permanent grasslands in herbivore diets that contribute to landscape attractiveness for hikers and naturalists. Second, the priority for livestock to provide services to cropping leads to a reduction in livestock numbers. Herbivores graze cover crops and monogastric animals produce animal manure that fully substitutes synthetic fertilizers. Feed resources with low digestibility of nutrients and animal housing are adapted to collective management of manure (e.g., methanisation), whose composition (e.g. N content) is of key importance. The reduction in livestock numbers leads to spare land for nature conservation in marginal areas. Third, human food production becomes marginal when patrimonial LFS are used primarily for biodiversity conservation, which is permitted by European agriculture subsidies that allow these systems to be maintained in upland and Mediterranean areas. Most agricultural stakeholders perceive predation of livestock by wild carnivores as a key issue in the first and third agroecological options. Finally, agricultural rewilding ensures only a limited but high-quality meat production, can support restoration projects, and benefits ecotourism, education and C sequestration. Our analysis opens a challenging research agenda for the animal science community. Key research issues are: (i) how to select animals adapted to fluctuating feed availability and quality, also limiting methane emissions through the selection of traits such as residual feed intake?, (ii) how to feed animals with resources with low N digestibility to maintain milk yield or growth performance while providing manure with high N content?, (iii) how to quantify the consequences of these options (and their combinations) on food production, biodiversity, GHG emissions per ha and per unit of product, and on C sequestration in agroecosystems?