Enteric Methane Emissions from Dairy-Beef Steers Supplemented with the Essential Oil Blend Agolin Ruminant.

Agriculture is the largest source of methane globally, and enteric methane accounts for 32% of methane emissions globally. Dairy-beef is an increasingly important contributor to the beef industry. The objective of this study was to investigate if supplementation with a blend of essential oils (Agolin Ruminant) reduced enteric methane emissions from dairy-bred steers. Methane was measured from thirty-six Holstein Friesian steers (18 control and 18 treatment) in open-circuit respiration chambers, at three time-points relative to the introduction of Agolin Ruminant: (i) -3 (pre-additive introduction co-variate), (ii) 46 days after introduction, and (iii) 116 days after introduction. A significantly lower methane yield was observed in treated animals compared to control animals at both 46 days (p < 0.05) and 116 days (p < 0.01) after the introduction of Agolin Ruminant, although there was no difference in methane production (g/day). Control animals appeared to be more affected by isolation in respiration chambers than animals receiving Agolin Ruminant, as indicated by a significant reduction in dry matter intake by control animals in respiration chambers.

A Meta-analysis Describing the Effects of the Essential oils Blend Agolin Ruminant on Performance, Rumen Fermentation and Methane Emissions in Dairy Cows.

There is an increasing pressure to identify feed additives which increase productivity or decrease methane emissions. This paper aims to elucidate the effects of supplementing a specific essential oils blend Agolin® Ruminant on the productivity of dairy cows in comparison to non-treated animals. A total of 23 in vivo studies were identified in which Agolin was supplemented at 1 g/d per cow; then a meta-analysis was performed to determine the response ratio on milk yield, rumen fermentation, methane emissions and health. Results indicated that an adaptation period of at least 4 weeks of treatment is required. Whereas short-term studies showed minor and inconsistent effects of Agolin, long-term studies (>4 weeks of treatment) revealed that Agolin supplementation increases milk yield (+3.6%), fat and protein corrected milk (+4.1%) and feed efficiency (+4.4%) without further changes in milk composition and feed intake. Long-term treatment also decreased methane production per day (-8.8%), per dry matter intake (-12.9%) and per fat and protein corrected milk yield (-9.9%) without changes in rumen fermentation pattern. In conclusion, despite the mode of action is still unclear and the small number of studies considered, these findings show that Agolin represents an encouraging alternative to improve productivity in dairy cows.

Genoprotective Effects of Essential Oil Compounds Against Oxidative and Methylated DNA Damage in Human Colon Cancer Cells.

Essential oils (EO) are widely used in foods as flavoring and preservative agents. Many of the biological activities of EO have been attributed to major essential oil compounds (EOC) but their direct interaction with colonic epithelial cells and their genotoxic and genoprotective effects are not well established. In this study, the cytotoxicity and genotoxicity of EOC including nerolidol, thymol, geraniol, methylisoeugenol, eugenol, linalool, and a commercial blend (Agolin) were determined. Furthermore, the genoprotective effects of EOC against oxidative and methylating damage were assessed using the comet assay in HT-29 colorectal adenocarcinoma cells. The majority of EOC were cytotoxic to HT-29 cells at or above 250 ppm after 24 hr exposure. At noncytotoxic doses, none of the EOC was genotoxic in the comet assay. Genoprotection against oxidative DNA damage was observed for nerolidol (at 62.5 ppm), thymol (at 12.5 ppm), geraniol, and methylisoeugenol (both at 125 ppm), as well as linalool and Agolin (both at 250 ppm). Thymol was the most protective compound against oxidative DNA damage and geraniol (at 125 ppm) also protected cells against methylating DNA damage. This study highlights the potential of EOC such as thymol to protect the colonic epithelium against oxidative DNA damage and geraniol against methylating DNA damage. Further in vivo studies are needed to confirm these findings for safety and efficacy to exploit their potential pharmaceutical or nutraceutical uses for colonic health.

Essential oils have different effects on human pathogenic and commensal bacteria in mixed faecal fermentations compared with pure cultures.

A static batch culture system inoculated with human faeces was used to determine the influence of essential oil compounds (EOCs) on mixed faecal microbiota. Bacteria were quantified using quantitative PCR of 16S rRNA genes. Incubation for 24 h of diluted faeces from six individuals caused enrichment of Bifidobacterium spp., but proportions of other major groups were unaffected. Thymol and geraniol at 500 p.p.m. suppressed total bacteria, resulting in minimal fermentation. Thymol at 100 p.p.m. had no effect, nor did eugenol or nerolidol at 100 or 500 p.p.m. except for a slight suppression of Eubacterium hallii. Methyl isoeugenol at 100 or 500 p.p.m. suppressed the growth of total bacteria, accompanied by a large fall in the molar proportion of propionate formed. The relative abundance of Faecalibacterium prausnitzii was unaffected except with thymol at 500 p.p.m. The ability of EOCs to control numbers of the pathogen Clostridium difficile was investigated in a separate experiment, in which the faecal suspensions were amended by the addition of pure culture of C. difficile. Numbers of C. difficile were suppressed by thymol and methyl isoeugenol at 500 p.p.m. and to a lesser extent at 100 p.p.m. Eugenol and geraniol gave rather similar suppression of C. difficile numbers at both 100 and 500 p.p.m. Nerolidol had no significant effect. It was concluded from these and previous pure-culture experiments that thymol and geraniol at around 100 p.p.m. could be effective in suppressing pathogens in the small intestine, with no concern for beneficial commensal colonic bacteria in the distal gut.

Sensitivity of pathogenic and commensal bacteria from the human colon to essential oils.

The microbiota of the intestinal tract plays an important role in colonic health, mediating many effects of dietary components on colonic health and during enteric infections. In the context of the increasing incidence of antibiotic resistance in gut bacteria, complementary therapies are required for the prevention and treatment of enteric infections. Here we report the potential application of essential oils (EO) and pure EO compounds to improve human gut health. Nerolidol, thymol, eugenol and geraniol inhibited growth of the pathogens Escherichia coli O157 : H7(VT(-)), Clostridium difficile DSM1296, Clostridium perfringens DSM11780, Salmonella typhimurium 3530 and Salmonella enteritidis S1400 at a half-maximal inhibitory concentration (IC(50)) varying from 50 to 500 p.p.m. Most EO showed greater toxicity to pathogens than to commensals. However, the beneficial commensal Faecalibacterium prausnitzii was sensitive to EO at similar or even lower concentrations than the pathogens. The EO showed dose-dependent effects on cell integrity, as measured using propidium iodide, of Gram-positive bacteria. These effects were not strongly correlated with growth inhibition, however, suggesting that cell membrane damage occurred but was not the primary cause of growth inhibition. Growth inhibition of Gram-negative bacteria, in contrast, occurred mostly without cell integrity loss. Principal component analysis showed clustering of responses according to bacterial species rather than to the identity of the EO, with the exception that responses to thymol and nerolidol clustered away from the other EO. In conclusion, the selective effects of some EO might have beneficial effects on gut health if chosen carefully for effectiveness against different species.