The Dose-Dependent Role of Sage, Clove, and Pine Essential Oils in Modulating Ruminal Fermentation and Biohydrogenation of Polyunsaturated Fatty Acids: A Promising Strategy to Reduce Methane Emissions and Enhance the Nutritional Profile of Ruminant Products

Abstract

The livestock industry significantly contributes to greenhouse gas emissions, with ruminant animals, including cows, sheep, and goats, being responsible for a substantial share of these emissions due to methane production. Reducing methane emissions from ruminants is crucial for mitigating the environmental impact of livestock production. Additionally, there has been a growing interest in improving the nutritional quality of ruminant products through modifying their profile of fatty acids. The current study aimed to investigate the potential of sage (SAG), pine (PIN), and clove (CLO) essential oils as natural additives for modulating in vitro ruminal fermentation characteristics and biohydrogenation of polyunsaturated fatty acids (PUFA). Within the current experiment, three dose levels (300, 600, and 900 mg/L) of essential oils were evaluated using rumen inoculum from three mature Dalagh ewes (58 ± 2.84 kg body weight). The results revealed that the essential oils had a significant impact on gas production, methane and carbon dioxide production, ruminal fermentation parameters, and ruminal biohydrogenation of dietary PUFAs. The essential oil treatments resulted in reduced gas production compared with the control group. Methane production was significantly reduced by all doses of the essential oils, with the highest dose of CLO resulting in the lowest methane production. In addition, the essential oils affected ruminal fermentation parameters, including pH, ammonia concentration, and production of total volatile fatty acids. Promising modifications in ruminal biohydrogenation of PUFAs and the profile of fatty acids were also observed in the current study. These findings suggest that SAG, Pin, and CLO hold promise in mitigating methane emissions and improve the nutritional value of ruminant products. Further investigation is required to evaluate their effectiveness in practical feeding strategies for livestock.

Efficacy of Salvia officinalis Shrub as a Sustainable Feed Additive for Reducing Ruminal Methane Production and Enhancing Fermentation in Ruminants

“…This supports the fact that a lower pH is related to a higher total SCFA concentration [ 45 ]. A higher pH with higher doses of sage essential oil was reported by Bokharaeian et al [ 18 ], which agrees with the findings of this study. The molar concentration of acetate changed linearly and quadratically and that of the propionate changed quadratically, with the highest concentration of both SCFAs shown at 1% inclusion of SO and then decreased with higher inclusion.…”

“…It was expected that the inclusion of SO would show anti-methanogenic activity by improving substrate degradability and the ruminal fermentation profile, and inhibiting methanogenic archaea, thereby decreasing CH 4 production. The production of CH 4 decreased linearly in the current study, which is concurrent with the findings of others in which dried leaves and sage essential oil were evaluated in vitro [ 9 , 10 , 18 , 38 ]. Patra and Saxena [ 39 ] demonstrated that essential oils, organosulfur compounds, and flavonoids can impact CH 4 production through the direct inhibition of methanogens without altering the population of protozoa.…”

“…The asymptotic GP of CO 2 and the rate of CO 2 increased linearly during the study, which contrasted with the findings of Bokharaeian et al [ 18 ] where the CO 2 decreased with greater levels of sage essential oil supplementation in vitro [ 18 ]. Increasing the propionate concentration at the expense of acetate could increase CO 2 [ 43 ].…”

“…Furthermore, whereas the dose-dependent response of the rate of gas production (/h) increased linearly with incremental levels of sage essential oil [12,18], a linear and quadratic response was observed in the current study, with the rate of gas production peaking at 1% inclusion of SO, and then decreasing thereafter. The lag in GP followed a similar trend, which confirms the inverse relationship between the lag in GP and asymptotic gas production [36,37], indicating that the highest GP with minimal lag was observed at 1% inclusion of SO.…”

“…To date, only a few studies have investigated the suitability of using SO as animal feed [ 9 , 10 , 12 , 17 , 18 ]. Also, the concentrations of secondary metabolites are much higher if whole plants are used rather than just leaves, which could be detrimental to rumen health and negatively affect ruminal fermentation parameters [ 16 , 19 ].…”