By Galen Erickson and Rick Rasby et.al
Methane (CH₄) is one of the three primary greenhouse gases (GHGs) contributing to global warming, alongside carbon dioxide (CO₂) and nitrous oxide (N₂O). Although methane comprises about 11% of total GHGs, it is significantly more potent in trapping heat than CO₂. Importantly, methane has a relatively short atmospheric half-life of 9 to 12 years, meaning reductions in methane emissions can yield quicker climate benefits compared to other GHGs.
In agriculture, methane emissions primarily stem from enteric fermentation in ruminants like beef and dairy cattle. These animals possess a rumen which is a large fermentation chamber populated by billions of microbes including bacteria, archaea (specifically methanogens), fungi, and protozoa. These microbes break down fibrous plant materials, enabling cattle to convert otherwise indigestible feed into useable energy and protein. However, this microbial digestion also produces methane, which is expelled through eructation (or burping). Cattle can produce 150 - 600 liters (40 - 160 gallons) of methane per day, and this process accounts for about 4% of the 10% of GHGs attributed to agriculture.
Methane production is influenced by several factors including diet, feed intake, animal and microbial genetics, and stage or phase of production. Research has shown that methane output is a moderately heritable trait, opening the door to genetic selection as a mitigation strategy. In fact, recent grants have been awarded to UNL researchers to explore genetic tools and microbiome management strategies aimed at reducing methane emissions without compromising animal performance.