Equine Contribution in Methane Emission and Its Mitigation Strategies

Area of Science:

• Environmental Science
• Animal Science
• Agricultural Science

Background:

• Greenhouse gas emission mitigation is crucial for earth sustainability, with a focus on reducing emissions from agricultural and petrochemical industries.
• Horses, as nonruminant herbivores, produce methane through hindgut fermentation, contributing to overall greenhouse gas output.
• While equine methane production is less than ruminants, a growing horse population could significantly increase their environmental impact.

Purpose of the Study:

• To explore factors influencing methane production in horses.
• To identify potential strategies for reducing methane emissions from equine populations.
• To assess the feasibility of applying these strategies to ruminants as well.

Main Methods:

• Review of factors affecting methane production, including diet, feeding frequency, season, host genome, and gut protozoa population.
• Identification of dominant methanogenic clades in equine hindgut (Methanomicrobiales, Methanosarcinales, Methanobacteriales, Methanoplasmatales).
• Analysis of natural mechanisms (acetogenesis, host-immune interactions) influencing methane output.

Main Results:

• Specific methanogenic clades like Methanomicrobiales and Methanocorpusculum labreanum are identified in equine hindgut fermenters.
• Natural acetogenesis and host-immune interactions contribute to reduced methane output in horses.
• Several potential interventions are proposed to mitigate equine methane emissions.

Conclusions:

• Strategies such as incorporating biochar, increasing acetogens, adding fiber enzymes and plant extracts, and anaerobic gas fermentation of feces show promise for reducing equine methane.
• These methods could enhance energy derived from feed intake in horses.
• The identified strategies may also be applicable to reducing methane emissions in ruminant livestock.