Effect of essential oils and aqueous extracts of plants on in vitro rumen fermentation and methane production

Abstract

The objective of this study was to evaluate in vitro rumen fermentation and methane production under the influence of two sources of phytochemicals: essential oils (EOs) and aqueous extracts (AEs). Treatments were set up in a completely randomized block design, with 4×2+1 factorial arrangement of four species, S (garlic, G; cinnamon, C; rosemary, R; eucalyptus; EU) × two types of presentation, P (essential oil, EO; aqueous extract, AE) and a basal diet, BD (50% concentrate, 20% alfalfa and 30% corn silage). Rumen fermentation was evaluated using the in vitro gas production technique. All experimental units were incubated with 500 mg of BD for 72 hours. Treatments were added at a single dose of 900 mg/L of rumen inoculum. Gas pressure was recorded at 0, 2, 4, 6, 8, 10, 14, 18, 24, 30, 36, 42, 48, 60 and 72 h postincubation. There was an interaction effect (P × S) between plant extract presentation (P) and plant species (S) for all variables. Treatments GEO, CEO, REO decreased volatile fatty acids (mmol/200 mg), microbial mass production (mg/g), CH4 production (mL/g), in vitro dry matter digestibility (P < 0.05), and total gas production at 24 and 72 h post-incubation (P < 0.05; mL/g DM, mL/g OM). No differences (P > 0.05) were observed between AEs and BD. In conclusion, the use of EOs negatively affected rumen fermentation parameters and the production of CH4. Garlic and cinnamon EOs effectively reduced methane emissions; however, they also reduced in vitro dry matter digestibility.

Essential Oil Blends with or without Fumaric Acid Influenced In Vitro Rumen Fermentation, Greenhouse Gas Emission, and Volatile Fatty Acids Production of a Total Mixed Ration

“…In this study, the rumen pH (6.61-6.69) was influenced by both the EOB inclusion and the EOB × FA interaction. The reduced pH was linked to a decrease in the gas production, DM disappearance, and total VFA concentration [19]. Expectedly, pH was reduced by 0.03 unit with the FA inclusion without compromising the TVFA concentration.…”

Effects of Different Essential Oil Blends and Fumaric Acid on In Vitro Fermentation, Greenhouse Gases, Nutrient Degradability, and Total and Molar Proportions of Volatile Fatty Acid Production in a Total Mixed Ration for Dairy Cattle

“…Microbial mass production in the present study was higher in the treatments containing EOBs compared to control and FA treatments, which may be related to lower gas production and the negative effects of the EOBs on methanogens [37]. Microbial mass in the rumen is an indication of the capacity of rumen microbes to convert feed sources [38], including proteins and carbohydrates, into microbial biomass and fermentation byproducts, such as VFA.…”

In Vitro Screening of the Foliage of Eucalyptus Species Harvested in Different Seasons for Modulating Rumen Fermentation and Methane Production

“…A number of studies have shown a significant level of in vitro antimethanogenic activity of eucalyptus leaves, extracts, and essential oils. The most studied species showing this activity have been E. camaldulensis [23,29] and E. globulus [21,[30][31][32][33][34] It is worth mentioning that some of these studies have shown that E. camaldulensis can be effective in decreasing methane production by rumen fermentation, whereas our study shows that other species (i.e., E. lehmannii or E. sideroxylon) could have a more noticeable effect on this fermentation gas. Wang et al [24] observed significant dose-dependent effects of a eucalyptus essential oil on methane production in vitro, but these effects could not be reproduced with sheep in vivo.…”