In vitro Screening of Essential Oil Active Compounds for Manipulation of Rumen Fermentation and Methane Mitigation

Area of Science:

• Rumen microbiology
• Animal nutrition
• Greenhouse gas mitigation

Background:

• Ruminant livestock are significant sources of enteric methane emissions.
• Essential oils contain active compounds with potential to modulate rumen fermentation.
• Reducing methane production can improve feed efficiency and environmental sustainability.

Purpose of the Study:

• To evaluate the impact of eleven active compounds of essential oils (ACEO) on in vitro rumen fermentation and methane production.
• To identify specific ACEO that reduce methane without negatively affecting volatile fatty acid (VFA) production.
• To further investigate the effects of the most promising ACEO, bornyl acetate, at different concentrations.

Main Methods:

• In vitro incubation of rumen fluid with a forage:concentrate substrate and various ACEO.
• Measurement of methane production and volatile fatty acid (VFA) concentrations.
• Comparison of ACEO effects against a control and, in a second trial, against monensin.

Main Results:

• Nine out of eleven ACEO reduced methane production, with up to 86% reduction observed.
• Bornyl acetate, limonene, 1,4-cineole, and α-pinene did not inhibit VFA production.
• Bornyl acetate at 500 and 2,000 μL/L decreased methane production and maintained VFA levels, outperforming monensin.

Conclusions:

• Bornyl acetate is a potent inhibitor of rumen methane production.
• It improves rumen fermentation efficiency by reducing methane without compromising VFA production.
• Bornyl acetate represents a promising strategy for mitigating methane emissions in ruminants.