Microbiome Manipulation to Reduce Methane Emission in Beef Cattle

Abstract Among the major sources of methane production, ruminants account for a considerable fraction of the anthropogenic methane produced. Thus, minimizing methane emission in intensive and extensive cattle production systems while maintaining/increasing performance of animals will have a significant impact on the environment and will help develop a sustainable carbon-based market system. We believe that developing science-based dietary intervention strategies using feed additives to manipulate rumen microbial communities is a viable strategy to reduce greenhouse gas emissions. Here we show the potential impact of using an essential oil formulation to reduce methane emissions in cattle. In this study, we used in-vitro fermentation experiments to evaluate the impact of the essential oil mix in reducing methane emissions. Additionally, we evaluated microbial community changes in the presence and absence of the essential oil mix to understand microbial changes that lead to reduced methane emissions. The in-vitro fermentation experiments demonstrated a significant decrease in methane emission in the essential oil mix compared with the control with no essential oil (P < 0.05). This decrease in methane was greater than 50%. Following in-vitro fermentation for 48 hours, the resulting inoculum was evaluated for microbial community changes using 16S rDNA sequencing. Compared with the control, the essential oil mix containing bottles were greater in Anaerovibrio and Succinivibrio and had a reduced abundance of Anaeroplasma and Prevotellaceae at the genus level. Furthermore, the essential oil mix tubes were plated to isolate members that were enriched in this treatment. The isolates obtained include Lysinibacillus halotolerans and Lysinibacillus boronitolerans. Such isolates may have the potential to be effective direct-fed microbial to reduce methane emission. Here we show the potential of the essential oil mix identified to reduce methane invitro and we have an animal study planned for the near future.