Effects of essential oils and their components on in vitro rumen microbial fermentation
Bibliographic record
Abstract
The objective of this study was to investigate the effects of essential oils (EO) and essential oil compounds (EOC) on in vitro rumen microbial fermentation. Treatments were: control (no additive), cinnamon leaf oil (400 mg L -1 ), clove leaf oil (200 mg L -1 ), sweet orange oil (200 mg L -1 ), oregano oil (200 mg L -1 ), thyme oil (200 mg L -1 ), carvacrol (400 mg L -1 ), cinnamaldehyde (400 mg L -1 ), eugenol (800 mg L -1 ), and thymol (400 mg L -1 ). Treatments were evaluated using in vitro 24-h batch culture of rumen fluid with a 51:49 forage:concentrate dairy ration [16.7% crude protein (CP), 34.4% neutral detergent fibre (NDF)]. Incubations were conducted in triplicate with gas production (GP) measured at 0, 2, 6, 8, 12, and 24 h, while pH, ammonia (NH 3 ), volatile fatty acid (VFA), in vitro dry matter (IVDMD) and neutral detergent fibre (IVNDFD) digestibilities were determined after 24 h of incubation. Among the EO and EOC evaluated, only the phenolic compounds, carvacrol, thymol, and eugenol affected ruminal fermentation, relative to the control. Carvacrol (400 mg L -1 ) and eugenol (800 mg L -1 ) increased pH and molar proportion of butyrate, and decreased molar proportion of propionate, IVDMD, IVNDFD, and GP. At the concentration of 200 mg L -1 , thymol increased final pH, a nd reduced molar proportion of propionate, IVNDFD, and GP. None of the EO or EOC affected NH 3 concentration, suggesting that at the doses tested in this study, protein degradation was not affected by EO and EOC. This study showed that among the EO and EOC investigated only phenolics exhibited antimicrobial activity as exemplified by reduced diet fermentability and a shift in VFA profile from less propionate towards more butyrate. These changes in fermentation may not be nutritionally beneficial to dairy cattle. The present study suggests that the types and concentrations of EO and EOC employed to alter ruminal fermentation must be carefully defined before their widespread use in ruminant nutrition can be recommended. Key words: Essential oil, ruminal fermentation, in vitro batch culture, dairy cattle
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".