Encapsulation of essential oils from tropical plants as a strategy to mitigate methane emissions and improve nutritional status of ruminants: A review

Climate change, primarily driven by rising greenhouse gas (GHG) emissions, presents a critical global challenge. Among agricultural sources, enteric methane (CH 4 ) from ruminant livestock contributes significantly to global GHG emissions and represents a considerable energy loss from feed. Phytogenic feed additives (PFAs), particularly essential oils (EOs), have shown promise in modulating rumen fermentation, suppressing methanogenic archaea, and enhancing nutrient utilization due to their antimicrobial, antioxidant, and bioactive properties. The EOs can enhance animal health and productivity while mitigating CH 4 emissions. Tropical plant-derived EOs, which contain volatile chemicals such as terpenoids and phenylpropanoids, have antimicrobial, antiviral, antioxidant, anticancer, and anti-inflammatory characteristics, which are beneficial for livestock health and performance. The bioefficacy of EOs is influenced by their phytochemical composition, including terpenoids and phenylpropanoids, which are susceptible to environmental degradation. To overcome stability and delivery challenges, encapsulation techniques, especially microencapsulation, are employed to protect EOs, prolong shelf life, and enhance bioavailability in the rumen. The physicochemical characteristics of encapsulated particles, such as size, wall material, and oxidative stability, critically influence their efficacy. This review critically discusses the potential of tropical plant-derived EOs and encapsulation technologies to improve ruminant productivity and mitigate CH 4 emissions, while highlighting research gaps and promoting sustainable livestock production systems.