Biomass use,production, feed efficiencies,and greenhouse gas emissions from global livestock systems

We present a unique, biologically consistent, spatially disaggregated global livestock dataset containing information on biomass use, production, feed efficiency, excretion, and greenhouse gas emissions for 28 regions, 8 livestock production systems, 4 animal species (cattle, small ruminants, pigs, and poultry), and 3 livestock products (milk, meat, and eggs). The dataset contains over 50 new global maps containing high-resolution information for understanding the multiple roles (biophysical, economic, social) that livestock can play in different parts of the world. The dataset highlights: (i) feed efficiency as a key driver of productivity, resource use, and greenhouse gas emission intensities, with vast differences between production systems and animal products; (ii) the importance of grasslands as a global resource, supplying almost 50% of biomass for animals while continuing to be at the epicentre of land conversion processes; and (iii) the importance of mixed crop–livestock systems, producing the greater part of animal production (over 60%) in both the developed and the developing world. These data provide critical information for developing targeted, sustainable solutions for the livestock sector and its widely ranging contribution to the global food system.The importance of the livestock sector as a user of natural resources, as a source of livelihoods, and as an engine of economic growth has been the focus of significant attention in the last decade (1–5). As the largest land-use system on Earth, the livestock sector occupies 30% of the world’s ice-free surface, contributes 40% of global agricultural gross domestic product, and provides income for more than 1.3 billion people and nourishment for at least 800 million food-insecure people, all the while using vast areas of rangelands, one-third of the freshwater, and one-third of global cropland as feed. In the process, livestock can both contribute valuable nutrients for crops and be responsible for nutrient pollution and land degradation, and they can both provide critically important protein and micronutrients to human diets and contribute to obesity. The sector has many dualities, and the roles played by livestock change depending on location and circumstances. However, there is growing recognition that improving the environmental performance of livestock systems as well as establishing sustainable levels of consumption of animal-sourced foods, are essential for the sustainability of the global food system (5–7).Insufficient attention has been paid to the generation of livestock data at the level of detail required for elucidating their future role in attaining key global sustainability goals. Some of these goals are poverty reduction, food and nutritional security, ecosystem protection, mitigation of greenhouse gases (GHG), and adaptation to climate change, for example. To date, global integrated assessments have included incomplete representations, at best, of the livestock sector (8–11). Some global analyses exist (1, 12–16); although these have focused on specific topics, such as biomass use, GHG emissions, and water footprints, they have required methodological simplifications to achieve global coverage. Such analyses fail to do justice to the considerable heterogeneity that exists in livestock production systems, management practices, resource-use efficiencies, and mitigation potentials. Detailed, disaggregated global livestock data are essential for informing policy analyses of the choices facing humanity in feeding the world, managing ecosystems, promoting economic growth, and sustaining the livelihoods of the poor. If the problems are global, the solutions are generally local and highly situation-specific: high-resolution spatially explicit data are critical if targeting of technology and policy to achieve sustainability is to be efficient and effective.Here we take one step toward filling a critical data gap for global change and sustainability research of the world’s food and ecosystems. We are unique in developing and describing a global, biologically consistent, spatially disaggregated dataset on biomass use, productivity, GHG emissions, and key resource-use efficiencies for the livestock sector, broken down into 28 geographical regions, 8 production systems, 4 animal species (cattle, small ruminants, pigs, and poultry), and 3 animal products (milk, meat, and eggs). We analyze the biological consistency of the data and discuss the main drivers of resource-use efficiency in the global livestock sector. We discuss how these data can contribute to the unraveling of key sustainability issues for the sector and conclude with further data and research needs.