Research on enteric methane mitigation in Chile: Ten years of scientific insights

Research on enteric methane abatement in Chile began approximately ten years ago and has steadily accelerated. A key challenge in developing strategies to decrease enteric methane emissions in Chile and other countries where ruminant production is largely pasture-based is that globally, most mitigation strategies have been developed and evaluated with confined ruminants fed total mixed rations, requiring adaptation and validation in pasture-based systems. In this review, we discuss in vitro and in vivo applied research of anti-methanogenic strategies conducted in Chile. The reviewed studies included the evaluation of grazing management, different genotypes and species of forages, seasonal forage crops, by-products, oilseeds, and algae supplementation, as well as the use of a chemical inhibitor of methanogenesis, 3-nitrooxypropanol, and the combination of more than one anti-methanogenic strategy. Global meta-analyses and reviews show that intensification of ruminant production consistently decreases methane output per unit of meat or milk and is often economically attractive to producers and acceptable to governments and consumers alike; however, it is generally associated with increased emissions of other greenhouse gases and can result in greater output of carbon dioxide equivalents. Results obtained in Chile with production intensification varied depending on the intensification strategy. We consider that at present, none of the anti-methanogenic strategies investigated thus far in Chile can be recommended for adoption in pasture-based systems. Important aspects to be addressed are the lack of published life cycle assessments, in vivo research in ruminants other than dairy cows, and a considerable proportion of research results available only as conference summaries. Efforts are ongoing to generate solutions to effectively and persistently decrease the emissions of greenhouse gases from Chilean ruminant livestock; however, more research is required to design, adapt, and evaluate enteric methane mitigation strategies applicable to pasture-based systems, which require greater funding from the public and private sectors.