Table 1.

Methane abatement strategies, mechanism of abatement, and considerations for use.

Methane abatement strategy	Mechanism of abatement activity	Considerations when selecting abatement strategy
Dietary composition
Increase hemicellulose/starch  Decrease cell wall components  Grinding	Increased passage rate; greater proportion propionate versus acetate; reduced ruminal pH	Shift methanogensis to hind gut or manure, risk of subacute ruminal acidosis (SARA)
Lipids
Fatty acids  Oils  Seeds  Tallow	Inhibition of methanogens and protozoa; greater proportion propionate versus acetate; biohydrogenation	Effect on palatability, intake, performance, and milk components; varies with diet and ruminant species; long-term studies needed
Defaunation
Chemical  Feed additives	Removes associated methanogens; less hydrogen for methanogenesis	Adaptation of microbiota may occur; varies with diet; maintenance of defaunated animals
Methanogen Vaccine	Host immune response to methanogens	Vaccine targets; diet and host geographical location differences
Monensin	Inhibits protozoa and gram-positive bacteria; lack of substrate for methanogenesis	Adaptation of microbiota may occur; varies with diet and animal; banned in the EU
Plant Compounds
Condensed tannins  Saponins  Essential oils	Antimicrobial activity; reduced hydrogen availability	Optimum dosage unknown; more in vivo research needed; long-term studies needed; may affect digestibility; residues unknown
Organic Acids
Fumarate  Malate	Hydrogen sink, greater proportion propionate versus acetate	Varies with diet; more in vivo research needed; long-term studies needed; may affect digestibility