Conclusion

The present study demonstrated that P. abrotanoides essential oil, characterized by a high content of oxygenated monoterpenes, effectively modulated in vitro rumen fermentation by reducing methane production and protozoal populations while improving microbial biomass production and microbial synthesis efficiency. However, higher supplementation levels also reduced nutrient degradability, indicating that excessive doses may adversely affect rumen fermentation. Among the tested concentrations, 200–300 mg/L appeared to provide the most favourable balance between methane mitigation and fermentation efficiency under the experimental conditions.

A major limitation of this study is that the findings were obtained under in vitro conditions, which may not fully represent the complexity of the in vivo rumen environment. Therefore, further in vivo studies are required to confirm the efficacy, safety, optimal supplementation level and long‐term effects of P. abrotanoides essential oil on animal performance, nutrient utilization and enteric methane emissions before practical application in ruminant production systems can be recommended.