title: In vitro Screening of Essential Oil Active Compounds for Manipulation of Rumen Fermentation and Methane Mitigation.
abstract: The objective of this study was to investigate the effects of 11 active compounds of essential oils (ACEO) on rumen fermentation characteristics and methane production. Two trials were conducted. In trial 1, ACEO (eugenol, carvacrol, citral, limonene, 1,4-cineole, p-cymene, linalool, bornyl acetate, α-pinene, and β-pinene) at a dose of 1,000 μL/L were incubated for 24 h in diluted rumen fluid with a 70:30 forage:concentrate substrate (16.2% crude protein; 36.6% neutral detergent fiber). Three fistulated Holstein cows were used as donors of rumen fluid. The reduction in methane production was observed with nine ACEO (up to 86% reduction) compared with the control (p<0.05). Among these, only limonene, 1,4-cineole, bornyl acetate, and α-pinene did not inhibit volatile fatty acid (VFA) production, and only bornyl acetate produced less methane per mol of VFA compared with the control (p<0.05). In a subsequent trial, the effects on rumen fermentation and methane production of two concentrations (500 and 2,000 μL/L) of bornyl acetate, the most promising ACEO from the first trial, were evaluated using the same in vitro incubation method that was used in the first trial. In trial 2, monensin was used as a positive control. Both doses of bornyl acetate decreased (p<0.05) methane production and did not inhibit VFA production. Positive effects of bornyl acetate on methane and VFA production were more pronounced than the effects of monensin. These results confirm the ability of bornyl acetate to decrease methane production, which may help to improve the efficiency of energy use in the rumen.
authors.affiliation: Institute of Animal Science, Prague Uhrineves 10400, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Joch
authors.affiliation: Institute of Animal Science, Prague Uhrineves 10400, Czech Republic.
authors.forename: L
authors.initials: L
authors.lastname: Cermak
authors.affiliation: Department of Forage Crops and Grassland Management, Czech University of Life Sciences, Prague 16521, Czech Republic.
authors.forename: J
authors.initials: J
authors.lastname: Hakl
authors.affiliation: Department of Microbiology, Nutrition and Dietetics, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Prague 16521, Czech Republic.
authors.forename: B
authors.initials: B
authors.lastname: Hucko
authors.affiliation: Institute of Animal Science, Prague Uhrineves 10400, Czech Republic.
authors.forename: D
authors.initials: D
authors.lastname: Duskova
authors.affiliation: Institute of Animal Science, Prague Uhrineves 10400, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Marounek
keywords: Bornyl Acetate; Essential Oil Active Compounds; Methane Production; Rumen Fermentation; Volatile Fatty Acid Production