The Potential of Strategies Used to Mitigate Enteric Methane Emissions in Nutrition Studies of Ruminants: A Review

Abstract

This study explored techniques with enteric methane (CH4) abating potential, ranging from chemical additives including 3-NOP, nitrate, and halogenated compounds to natural feed additives such as tannins, oils, seaweed extracts, and probiotics. Most of the evaluated strategies exert their influence either by promoting the growth of ruminal microbes that compete with methanogens for metabolic hydrogen as their resource or by directly consuming CH4. Additionally, externally supplied probiotics, including propionate-forming bacteria and methane-oxidizing bacteria, are a promising tool. However, challenges persist in implementing these strategies effectively. High doses of chemical additives and plant based secondary metabolites often achieve significant CH4 reduction, but they are associated with negative impact on dry matter intake and digestibility, thus compromising overall animal performance. On the other hand, using lower doses to maintain animal performance may not achieve beneficial CH4 reduction. Furthermore, concerns about the impact of certain additives on human health have led to a shift towards more natural alternatives, but their efficacy and feasibility in vivo necessitate further evaluation. Comprehensive research that integrates data from diverse global experiments on ruminants through meta-analytical approaches is essential. Such research will help in identify strategies that either reduce methane emissions and/or enhance production performance, ensuring sustainable livestock farming practices. In conclusion, mitigating CH4 emissions from ruminant livestock is a complex challenge with wide-ranging implication.