Carbon and nitrogen footprints of Northern Chinese sheep and goat in the context of “Carbon Neutrality”

The goals of carbon neutrality and environmental sustainability are driving the global transition to a low-carbon and low-nitrogen economy. As a key component of agriculture, livestock and poultry farming is a significant source of carbon and nitrogen emissions. Specifically, among meats products, ruminant-derived meats have the highest carbon and nitrogen footprints. However, a systematic study on the carbon and nitrogen footprints of sheep remains underexplored. This study aims to address this gap by conducting a detailed assessment of the carbon and nitrogen footprints of goats and sheep across different farming modes in North China, employing a full life cycle assessment (LCA) approach. The LCA includes emissions from feed production, enteric fermentation, manure management, and energy consumption. The results show that the average carbon footprint of sheep is 19.10 kg CO₂-eq/kg carcass weight (CW), slightly higher than the 18.9 kg CO₂-eq/kg CW for goats. In contrast, sheep have an average nitrogen footprint of 127 g N-eq/kg CW, lower than the 191 g N-eq/kg CW for goats. Emissions decrease as production scales increase, with sheep generally showing a lower overall environmental impact. This reduction stems from three key factors: higher feed conversion efficiency in mixed systems; improved manure management lowering methane from anaerobic decomposition compared to unmanaged grazing manure; and reduced emissions from feed cultivation, as optimized feed composition and lower overall consumption in mixed systems decrease fertilizer and energy use during crop growing. These findings not only provide valuable insights into the environmental sustainability of sheep farming but also offer practical emission reduction strategies. By linking these findings to global carbon neutrality goals, this study contributes to the advancement of sustainable livestock farming and environmental stewardship in the long term.