നെലോർ കന്നുകാലികളിലെ മീഥെയ്ൻ ബഹിർഗമനം കുറയ്ക്കാൻ പുതിയ പഠനം: ശാസ്ത്രജ്ഞർ നിർണ്ണായക കണ്ടെത്തലുകളിൽ

Researchers at the Brazilian Agricultural Research Corporation (EMBRAPA) are studying the relationship between the genetics of Nelore cattle and the microorganisms in their guts (microbiota). Nelore cattle are the most widely raised beef breed in Brazil. The goal is to develop strategies that reduce emissions of methane—a major greenhouse gas—and improve the animals' feed efficiency.

Luciana Regitano, a researcher at the Embrapa Pecuária Sudeste unit in São Carlos in the state of São Paulo, presented some of the key findings of the research. The presentation took place on Wednesday, Oct. 28, during FAPESP Week Netherlands.

In an interview with Agência FAPESP, Regitano explained that the team identified key factors in regulating cattle digestion and methane emissions. "Our data show how variation in the expression of microbial genes is directly connected to two factors of great economic and environmental interest: the volume of methane generated and the efficiency of feed utilization."

Livestock farming is one of the main sources of greenhouse gases. Methane is produced during the natural digestion of cattle, a process commonly known as "cattle burping." In the rumen, the largest chamber of the animal's stomach, microorganisms break down plant fibers and produce the gas in the process. In addition to its climate impact, this production consumes 2% to 12% of the energy that the cow would otherwise obtain from its feed.

To understand and intervene in this process, the EMBRAPA team uses a combination of molecular biology techniques to simultaneously analyze DNA, RNA, proteins and other chemical substances. "We analyze the tissues of the cattle and the components of the microbiota in their digestive systems," said Regitano.

New solutions

By mapping the RNA molecules produced in the rumen, the scientists identified enzymes linked to improved feed utilization and reduced methane production. These enzymes represent biotechnological targets for developing new feed additives for cattle. "The detailed identification of rumen enzymes and metabolic pathways paves the way for biotechnological solutions applicable to beef cattle production," the researcher stated.

One of the most advanced lines of research involves formulating compounds that can block or slow down the enzymes responsible for methane formation. Although commercial additives that act at the end of this process already exist, EMBRAPA's data reveal new metabolic pathways for creating more precise and efficient inhibitors.

However, intervening in cattle digestion requires caution. Methane production absorbs the free hydrogen left over from feed fermentation. If gas formation is simply blocked, the accumulation of hydrogen can make the stomach acidic (changing the pH) and impair digestion. "Our strategies aim not only to inhibit the enzyme that generates methane, but also to redirect this hydrogen to beneficial metabolic pathways, such as the production of propionate, an essential fatty acid that serves as an important energy source for the bovine," Regitano explained.

Another line of research focuses on developing probiotics, which are beneficial live microorganisms, and prebiotics, which are dietary ingredients and fibers that selectively nourish desirable bacteria. By identifying the nutritional needs of bacteria associated with lower gas emissions and high feed conversion, the researchers can formulate dietary supplements to promote the permanent colonization of these strains in the rumen.

The team is also studying how cattle regulate the microorganisms in their stomachs themselves. To accomplish this, the scientists isolated tiny transport vesicles (nanovesicles) produced by the animals' bodies. These vesicles carry resistant molecules (microRNAs) that help regulate gene activity.

"We discovered that certain microRNAs produced by cattle have a strong connection, in computer simulations, with the functioning of genes in rumen microorganisms," Regitano explained. The hypothesis—which is now undergoing laboratory testing—is that the animal uses these molecules to modulate the bacteria in its stomach. Since these microRNAs are stable and easy to reproduce artificially, they could form the basis of new regulatory technologies.

Economic barrier

The team has already identified genetic markers in cattle associated with certain microorganisms. However, directly selecting beef cattle with the best microbiota still faces cost barriers, as Regitano points out.

"Unlike what's observed in poultry farming, pig farming or dairy farming, scientific literature and our own data confirm that direct genetic selection to alter the microbiota in beef cattle doesn't present a favorable financial return with current technologies," she said. "The cost of sequencing the microbiota and incorporating that information into genomic selection indices is very high relative to the gains in production performance or reduction in emissions.

"However, in partnership with geneticists, we continue to evaluate whether new assessment methodologies and more affordable sequencing could change that equation in the future."

In a study conducted with the Brazilian Association of Zebu Breeders (ABCZ), the group monitored Nelore cattle from pasture to final fattening in feedlots. The study showed that the bacteria that colonize a calf's stomach while it is still on pasture influence the animal's development for the rest of its life.

"We identified various microorganisms present in the initial pasture phase that strongly correlate with the measured feed efficiency and weight gain months later, when the animal is already in confinement," Regitano reported. "That demonstrates that, although the diet changes radically from pasture to concentrated feed, the initial pasture-based microbial colonization creates a favorable physiological and nutritional environment whose benefits persist until slaughter."

The studies also revealed that the stomach microbiota influences behavioral traits in cattle. This finding underscores the importance of viewing cattle as holobionts—a concept that defines the host animal and its entire community of microorganisms as a single, integrated ecological unit. EMBRAPA is now expanding the research to other breeds and climates in partnership with institutions in the United States, Ireland, Germany, Australia and the Netherlands.

"The consolidation of those international networks allows us to understand how different environments and genotypes interact with the microbiome, ensuring that scientific advances translate into practical and sustainable technologies for tropical livestock farming," said Regitano.

Unknown microorganisms

Despite these advances, the studies revealed a significant scientific challenge: the vast majority of microorganisms living in the rumen are completely unknown. "Around 40% of what we identified in the Nelore cattle samples aren't listed in any international database. We encountered a large number of genes whose function in the organism is still unknown," the researcher reported.

The analyses indicate that approximately 48% of the microbial species found may be previously unknown to science, most of which have never been isolated in a laboratory. To address this gap, Regitano has partnered with experts in bioinformatics and artificial intelligence (AI).

"That technology allows us to predict the function of genes quickly. Next, we plan to isolate those microorganisms and express their proteins in laboratory tests, experimentally validating what we discovered in computer simulations," the researcher explained.