Antimethanogenic activity of essential oils extracted from Rosmarinus officinalis and Lavandula officinalisAuthor(s): B.Djabri, R.Rouabhi, R.Arhab, F.Attar, H.Bousseboua
Methane constitutes the main way of hydrogen elimination in the rumen during the microbial digestion of food. Its eructation by ruminants led to both energy loss for animals and a worsening of the greenhouse by its radioactive power. The aimof this study focuses on exploring the ability of essential oils (EO), extracted fromrosemary (Rosmarinus officinalis) and lavender (Lavandula officinalis), in reducing ruminalmethanogenesis.Activity of essential oils extractswas compared to that of purified essential oils (carvacrol, cinnamaldehyde and thymol). The aerial parts of plants (rosemary and lavender) are used fresh. Extraction of EO was made by the hydrodistillation process.Antimethanogenic activity of EO extracts was measured in vitro in batch systems (polypropylene syringes, 60 ml capacity). EO extract of each plant and purified EO (carvacrol, cinnamaldehyde and thymol) were tested at different doses: 10, 20 and 40 ìl. Gas production was monitored at different time intervals: 2, 4, 6, 8, 24, 48 and 72 h. The qualitative and quantitative analysis of fermentative gas (CH4 and CO2) was chemically determinate after 24 hours incubation. The results indicate that addition of crude oils of Rosmarinus officinalis and Lavandula officinalis and the purified oils did not affect significantly the pH values (P > 0.05). The addition of EO of both plants did not affect gas production after 2 hours of fermentation (P > 0.05) for the three doses. Between 4 and 6 h of incubation, increasing EO dose of Lavandula officinalis induces a continuous decline (but not significant) of the gas production compared with the control (no additives). Similarly, addition of Rosmarinus officinalis essential oils had not significant effect on gas production for 10 and 40 ìl doses compared with control. However, higher gas productionwas recorded for 20ìl dose. Addition of Lavandula officinalis EOat 40µl level caused significant decrease in gas production after 24h incubation (P < 0.05). Methane production was significantly reduced in the presence of EO extracted fromRosmarinus officinalis (28.1%; P < 0.05). Besides, EOextracted fromLavendula officinalis decrease significantlymethane production during 24 hours of incubation for 10 and 40ìl doses. In general, EO used in our study showed a significant effect on reducing methane. Thus, we can focus future research on composition characterization of each essential (CGÂMS) and to determine minimal inhibitory concentration (MIC) allows maximum methane reduction without adverse effects on digestibility.