Enteric Methane Emission and Amelioration Strategies in Ruminants

Ruminants play a vital role in global food systems by converting forages from non-arable lands into high-quality animal protein. However, 2-12% of gross energy is lost as enteric methane (CH4), contributing nearly 6% of global anthropogenic greenhouse gas emissions. This review synthesizes current knowledge on the global CH4 production scenario, methanogenesis, and emerging mitigation strategies, including animal genetics, vaccine development, diet formulation, fermentation modifiers, chemical inhibitors, and early life programming. While most approaches yield moderate reductions (<20%), experimental use of 3-nitrooxypropanol has achieved consistent CH4 decreases of 20-40%. Future progress will require integrating multiple strategies to achieve significant abatement, alongside improved cost-effectiveness, applicability in grazing systems, and validation of impacts on animal performance, health, and product quality.