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

M Joch,L Cermak,D Duskova,B Hucko,M Marounek,J Hakl

doi:10.5713/ajas.15.0474

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.

Highlights

In ruminants, methane is a natural by-product of anaerobic respiration, and its production serves as the principal electron sink in the rumen
Results of the effects of active compounds of essential oils (ACEO) (1,000 μL/L) on in vitro methane production and rumen fermentation characteristics are presented in Table 2 and 3
At the treatment dose of 1,000 μL/L, the most pronounced inhibition of methane production was noted for carvacrol, with the magnitude of inhibition decreasing in the following order: carvacrol (–86%), citral (–44%), bornyl acetate (–38%), α-pinene (–29%), β-pinene (–28%), eugenol (–24%), linalool (–24%), limonene (–23%) and 1,4-cineole (–22%)

Summary

Introduction

Methane is a natural by-product of anaerobic respiration, and its production serves as the principal electron sink in the rumen. Methane represents a significant loss of dietary energy (Beauchemin et al, 2008). The ultimate aims in manipulating ruminal fermentation are to maximize the efficiency of feed utilization and increase ruminant productivity. Considerable research effort has focused on methods to modify ruminal fermentation. 17, 2015; Accepted Oct. 8, 2015 successful in reducing energy and protein losses (Nagaraja et al, 1997). The use of antibiotics in animal feed is facing reduced social acceptance because of the appearance of residues and resistant strains of bacteria; their use has been banned in the European Union since January 2006 (Directive 1831/2003/CEE, European Commission, 2003)

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