Study maps Nelore cattle microbiota to reduce methane emissions

Researchers at Brazil's EMBRAPA are studying the relationship between genetics of Nelore cattle (a popular beef breed in the country) and the microbes in their guts, called microbiota. The aim is to devise methods to lower methane emissions—a significant greenhouse gas—and enhance the animals' feed efficiency.

Luciana Regitano, a researcher at the Embrapa Pecuária Sudeste unit in São Carlos, São Paulo, presented some key findings from the research during FAPESP Week Netherlands. She explained that her team identified critical factors regulating cattle digestion and methane emissions. Their data demonstrate a direct link between variation in the expression of microbial genes and two important economic and environmental factors: methane production volume and feed utilization efficiency.

Cattle burp methane during digestion in their rumen, the largest chamber of the stomach. Microorganisms break down plant fibers here, producing methane as a byproduct, which also consumes 2% to 12% of the energy the cow could otherwise get from its feed. To tackle this, the EMBRAPA team uses molecular biology techniques to analyze DNA, RNA, proteins, and other substances from the cattle and their microbiota.

By mapping RNA molecules in the rumen, scientists found enzymes linked to better feed utilization and reduced methane production. These enzymes are potential biotechnological targets for new feed additives. However, caution is needed in intervening in cattle digestion, as methane production absorbs leftover hydrogen from feed fermentation.

If gas formation is blocked, hydrogen accumulation can make the stomach acidic, impairing digestion. Therefore, new strategies aim to inhibit methane-generating enzymes while redirecting hydrogen to beneficial metabolic pathways, such as producing propionate, an essential fatty acid for bovines.

Another research line focuses on developing probiotics (beneficial live microorganisms) and prebiotics (dietary fibers that nourish desirable bacteria). By understanding the nutritional needs of bacteria linked to lower gas emissions and high feed conversion, researchers can create dietary supplements to encourage these strains' permanent colonization in the rumen.

The team is also investigating how cattle regulate their stomach microbes through tiny transport vesicles (nanovesicles) containing microRNAs that regulate gene activity in rumen microbes. These stable, easy-to-replicate microRNAs could form the basis of new regulatory technologies.