Table 2 Effects of Thymbra capitata essential oil (natural –NEO– and synthetic –SEO–) and their main pure bioactive compounds (included at the same concentration as when EO is added at a rate of 75 mg carvacrol/L) on ruminal fermentation end-products after 24 h in vitro incubation of a high concentrate diet in batch cultures with mixed rumen microorganisms.
Control | NEO | SEO | carvacrol | p-cymene | γ-terpinene | SEM | P value | |
|---|---|---|---|---|---|---|---|---|
Gas (mL) | 146 | 144 | 144 | 150* | 150* | 149 | 0.82 | < 0.001 |
Methane (µmol) | 586 | 564 | 538 | 554 | 601 | 569 | 45.82 | 0.937 |
Total VFA (µmol) | 2675 | 2529* | 2628 | 2679 | 2692 | 2575 | 33.50 | 0.020 |
Molar proportions (µmol/100 µmol) | ||||||||
Acetate | 59.5 | 57.8* | 59.4 | 59.5 | 59.6 | 58.7 | 0.421 | 0.056 |
Propionate | 13.7 | 12.2 | 12.0 | 12.4 | 13.0 | 12.9 | 0.575 | 0.374 |
Butyrate | 18.5 | 19.6 | 18.7 | 18.3 | 18.6 | 19.0 | 0.370 | 0.281 |
Valerate | 2.29 | 2.49 | 2.43 | 2.46 | 2.34 | 2.40 | 0.054 | 0.152 |
Caproate | 3.98 | 6.02* | 5.61* | 5.40 | 4.42 | 4.98 | 0.373 | 0.014 |
Isoacids | 2.03 | 1.88 | 1.90 | 1.87 | 1.99 | 1.97 | 0.048 | 0.153 |
Ac:Pr (mol/mol) | 5.14 | 5.75 | 5.87 | 5.69 | 5.48 | 5.47 | 0.28 | 0.518 |
Methane/VFA (mol/mol) | 0.223 | 0.228 | 0.204 | 0.207 | 0.225 | 0.225 | 0.017 | 0.857 |
NH3-N (mg/L) | 242 | 255 | 244 | 244 | 249 | 266 | 9.82 | 0.533 |
