Assessment of different phytogenic-based additives on in vitro rumen fermentation profile and methane emissions

NL and IL supplementation significantly (<i>p</i> < 0.05) increased gas and carbon dioxide (CO₂) production, organic matter degradability, and total volatile fatty acid concentrations, particularly propionate and butyrate. Simultaneously, acetate concentration, CH₄ emissions, NH₃-N levels, and protozoa abundance were reduced (<i>p</i> < 0.05). However, PP had limited effects on these parameters. The phenolic profiles of NL and IL, notably rich in 2-hydroxycinnamic acid and p-coumaric acid, likely contributed to these outcomes. In conclusion, these findings support the use of NL and IL as effective phytogenic additives for improving rumen fermentation and mitigating CH₄ production. Further <i>in vivo</i> trials are recommended to validate these <i>in vitro</i> results.