# Influence of Oregano Essential Oil on the Rumen Microbiome of Organically Reared Alpine Goats: Implications for Methanobacteria Abundance

## TL;DR

This study shows that adding oregano essential oil to the diet of dairy goats reduces methane-producing microbes in their rumen, offering a natural way to cut livestock emissions.

## Contribution

The study demonstrates that oregano essential oil can reduce Methanobacteria in the rumen of dairy goats, presenting a novel natural strategy for methane mitigation.

## Key findings

- OEO supplementation significantly reduced Methanobacteria abundance in the rumen over time.
- Both generic and archaeal-specific analyses confirmed the reduction in methane-producing microbes.
- The effect was dose-dependent, with higher OEO doses showing greater reductions.

## Abstract

The reduction of methane emissions originating from the livestock sector is of high importance towards the confrontation of climate change. In the present study, the effect of organic oregano (Origanum vulgare) essential oil (OEO) incorporated into the feeding ratio in lactating dairy goats over a 45-day period, on the abundance of the Methanobacteria population in their rumen was investigated. Samples were collected on days 15, 30 and 45 of the feeding trial to investigate the alterations in microbial populations, using both generic microbial and archaeal-specific primer pairs. From the results, it occurred that the animals receiving OEO were characterized by lower Methanobacteria abundances over time compared to animals that did not receive the supplementation with OEO. This effect was observed using both analytical approaches targeting generic and archaeal-specific microbial communities. These findings are important because they show a promising, environmentally friendly method for making livestock farming more sustainable.

The present study aimed to evaluate the effects of dietary supplementation with organic oregano (Origanum vulgare) essential oil (OEO) on the rumen microbial population, with a focus on methanogenic archaea, in lactating dairy goats. A total of nine age-matched goats (mean body weight 49 ± 1.8 kg) were assigned to three experimental groups (n = 3 per group) in a completely randomized design. All animals were fed a basal diet consisting of a corn-based concentrate and a forage mix composed of alfalfa hay, wheat straw and corn silage. Group 1 was the control group while Groups 2 and 3 received an OEO supplement at dosages of 1 mL/day and 2 mL/day per animal, respectively, incorporated into the concentrate feed. Rumen fluid samples were collected on days 15, 30 and 45 of the feeding trial and their microbial profile was assessed using NGS analysis. The results demonstrated a reduction in the relative abundance of methanobacteria in both OEO-supplemented groups compared to the control group. Statistical analysis revealed significant differences between feeding groups and days of sampling. These findings suggest that OEO has the potential to modulate the rumen microbiome by reducing methane-producing archaeal populations. In conclusion, dietary supplementation with OEO may serve as a natural strategy to mitigate enteric methane emissions in Alpine dairy goats.