Dietary mitigation of enteric methane emissions from ruminants: A review of plant tannin mitigation options

Abstract

Methane gas from livestock production activities is a significant source of greenhouse gas (GHG) emissions which have been shown to influence climate change. New technologies offer a potential to manipulate the rumen biome through genetic selection reducing CH 4 production. Methane production may also be mitigated to varying degrees by various dietary intervention strategies. Strategies to reduce GHG emissions need to be developed which increase ruminant production efficiency whereas reducing production of CH 4 from cattle, sheep, and goats. Methane emissions may be efficiently mitigated by manipulation of natural ruminal microbiota with various dietary interventions and animal production efficiency improved. Although some CH 4 abatement strategies have shown efficacy in vivo, more research is required to make any of these approaches pertinent to modern animal production systems. The objective of this review is to explain how anti-methanogenic compounds (e.g., plant tannins) affect ruminal microbiota, reduce CH 4 emission, and the effects on host responses. Thus, this review provides information relevant to understanding the impact of tannins on methanogenesis, which may provide a cost-effective means to reduce enteric CH 4 production and the influence of ruminant animals on global GHG emissions.

Phytogenic Additives Can Modulate Rumen Microbiome to Mediate Fermentation Kinetics and Methanogenesis Through Exploiting Diet–Microbe Interaction

“…For example, a decrease up to 25 to 50% was observed in in vitro CH 4 production in steers grazing on winter wheat forage (15 to 18% CP) supplemented with quebracho CT extract at 10–20 g/kg DMI ( 227 , 228 ). This shows the effective inhibitory effects of tannins on ruminal protein degradation and CH 4 emission but requires careful selection of diets and nutrient composition to avoid adverse effects on feed digestibility and efficiency ( 229 ). However, further studies are required to fully understand the mechanism of action of tannins regarding modulation of the rumen microbiome, potential inhibitory effects on methanogens and protozoa, and their optimum inclusion levels to elucidate their potential for CH 4 mitigation.…”

Examining the Variables Leading to Apparent Incongruity between Antimethanogenic Potential of Tannins and Their Observed Effects in Ruminants—A Review

“…Recent studies have shown that the effect of tannins on ruminant nutrition is highly dependent on the tannin type, structural characteristics, dosage supplied, rumen morphology, and rumen physiology [102,103]. Numerous plant species containing tannins have been studied to determine their efficacy in ruminant nutrition, either as forages or feed additives.…”

Metabolic Benefit of Bulls Being Fed Moringa Leaves Twigs and Branches as a Major Concentrate Ingredient

“…There may be lower need for conversion of dietary GE to CH 4 when a diet with more digestible ingredients is fed to cattle (Kurihara et al, 1999;Liu et al, 2017). Therefore, dietary strategies were reported to be effective in reducing enteric CH 4 emissions in ruminants (Kebreab et al, 2010;Gastelen et al, 2019;Min et al, 2020). Regarding this, Benchaar et al (2001) quantified that dietary manipulation may reduce up to 40% of enteric CH 4 emissions.…”