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

Introduction: Phytogenic feed additives have gained increasing attention in ruminant nutrition due to their capacity to modulate ruminal fermentation and reduce methane (CH₄) emissions. This study evaluated the effects of three plant-based additives.

Methods: Neem leaf (Azadirachta indica; NL), Indigofera leaf (Indigofera oblongifolia; IL), and Pumpkin peel (Cucurbita pepo; PP) included at four levels (0, 10, 20, and 30 g/kg DM) on in vitro ruminal fermentation, feed degradability, and CH₄ emissions. A total mixed ration (TMR) was incubated with each additive and buffered rumen fluid using the in vitro gas production technique for 24 hours.

Results and discussion: NL and IL supplementation significantly (p < 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 (p < 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 in vivo trials are recommended to validate these in vitro results.