Strategies Used to Reduce Methane Emissions from Ruminants: Controversies and Issues

Methanogenesis plays a crucial role in the digestive process of ruminant animals. During this process, methanogenic archaea produce methane as a byproduct of their metabolism. However, the production of methane by ruminants is also a significant contributor to greenhouse gas emissions. Methane is a potent greenhouse gas that has a 28-fold greater global warming potential than carbon dioxide. Around 15% of all anthropogenic greenhouse gas emissions are generated by livestock. Therefore, reducing methane emissions from ruminant livestock is an important goal for reducing the environmental impact of agriculture. There is a variety of strategies that can be used to reduce methane emissions, including dietary modifications, genetic selection, microbiome manipulation, and feed additives, such as plant secondary metabolites, methane inhibitors, lipids, essential oils, and algae. The main and important objective of this paper is to critically discuss the current strategies proposed to reduce methane emissions from livestock. Though many strategies, such as chemical intervention, have remarkably reduced methane emissions from ruminants, their usage remains unappealing because of health and safety concerns as well as consumer decisions. Hence, genetic animal selection and biological feed additives, such as probiotics and secondary plant metabolites, have emerged as promising techniques for mitigating enteric methane emissions. These strategies are highly promising, but more intensive research is needed to validate these approaches and assess their effectiveness in reducing methane production by ruminants.