Abstract
From a global warming perspective, methane (CH4) produced by ruminants is considered a major environmental issue. The use of encapsulated essential oils in ruminant nutrition is one of the most recent strategies to reduce enteric CH4 emission. The objective of this review is to discuss how essential oils can be used to reduce CH4 production when added to ruminant diets. Essential oils have antimicrobial and anti-methanogenic properties that may alter the rumen fermentation patterns and microbial populations. The bioavailability of essential oils is highly compromised as they pass through the gastrointestinal tract due to heat, pressure, low pH, or digestive enzymes. The encapsulation technologies, micro and nanoencapsulation, protect the essential oils from degradation and facilitate site-specific delivery in the rumen. The ability of the encapsulated essential oils to reduce CH4 production is demonstrated by their inhibitory effects on methanogenic microorganisms and enhancement of fermentation pathways. Encapsulated essential oils help to reduce environmental concerns and offer potential benefits for livestock productivity. Supplementing encapsulated essential oils to feed for livestock offers both potential benefits and challenges. The advantages include a decrease in greenhouse gas emissions and enhanced feed efficiency; however, the effectiveness varies based on the specific essential oil used, the encapsulation methods, and the unique traits of each animal. In addition, because of the importance of regulatory and safety considerations, detailed risk assessment and compliance with safety regulations are crucial for broad adoption. Further research will be necessary to optimize encapsulation techniques, explore new essential oils, and address regulatory challenges. In conclusion, encapsulated essential oils present a promising strategy for mitigating CH4 emissions from ruminants. Their ability to improve feed efficiency and reduce environmental impact aligns with global sustainability goals.