Analyze This: Cows burp less methane after early-life treatment

Calves getting the 14-week treatment belch less of the greenhouse gas over a year

a trio of young cows looks at the viewer

Microbes in cows’ bellies chow down on fiber and pump out methane, a greenhouse gas. In a new study, young cows received a daily dose of a methane-blocking chemical. These animals belched less methane over their first year, compared to cows not getting the treatment.

Alex Walker/ Moment/Getty Images Plus

Belching cows give off much of the methane that comes from raising farm animals. Now researchers have found a way to make a long-lasting slash to how much potent greenhouse gas is burped by cows.

Cows are ruminants. Their stomachs contain multiple sections for digesting greens. Ruminants’ gut microbes help break down tough plant fiber through fermentation. That process churns out a lot of gas, including methane. 

Certain chemicals can cut the burping beasts’ methane by up to 30 percent. But if you stop feeding cows those compounds, their methane emissions go back to normal, says Diego Morgavi. He’s a veterinarian and biologist based in Clermont‑Ferrand, France. He works at France’s National Research Institute for Agriculture, Food and the Environment.

Many studies have examined the chemicals’ impact on methane in adult ruminants. Morgavi and his team suspected they might see something different in young animals. So they fed a group of dairy calves a methane-blocker. The animals received this chemical daily during their first 14 weeks of life.

Sensors at feeding stations measured methane in the cows’ gas while the animals were nearby. That allowed the team to estimate the methane being belched out each day. Over their first year of life, treated cows released about 9 percent less methane than did a group of cows not given the chemical. The scientists shared their findings February 4 in Scientific Reports.

The team examined the microbiome, the community of microbes, in the cows’ guts throughout the year of the study. Treated cows had a different set of microbes than the control cows. That difference may explain why the treatment cut the cows’ methane.

Like players on a soccer team, different microbes in the gut perform different tasks, Morgavi says. Compared with youngsters, adult animals have a large, diverse mix of microbes. Knock out one microbial player and others may fill in to do the same job. But early in life, the microbial community may be easier to change. Starting the treatment at birth may shape the cows’ microbiomes during a key stage of life. And that may affect how much methane the microbiome produces as the cows mature. But it’s not yet clear which microbes are the most important. The team also plans to study how the treatment works on other ruminants, including cattle raised for beef.  

line graph shows the amount in grams of methane per day from cows that received a methane-blocking chemical (circles and solid line) and those that didn’t (triangles and dashed line)
This line graph shows the amount in grams of methane per day from cows that received a methane-blocking chemical (circles and solid line) and those that didn’t (triangles and dashed line). The measurements began after the animals were weaned, when they stopped receiving milk from their mothers.S.J. Meale et al/Scientific Reports 2021

 Data Dive:

  1. How does methane production in treated cows at week 12 compare with week 1?
  2. How does methane production in the control group (cows that were not given the chemical) at week 12 compare with week 1?
  3. Over which weeks do trends in the two sets of data differ?
  4. How would you estimate the average difference in methane emissions for each group?
  5. The graph doesn’t show data for weeks 13 through 45. Based on the available data, can you guess what the data may look like between weeks 13 and 45? Which set of cows likely gave off more methane? For each group, does its methane emissions likely increase, decrease or stay the same over time?

Carolyn Wilke is a former staff writer at Science News Explores. She has a Ph.D. in environmental engineering. Carolyn enjoys writing about chemistry, microbes and the environment. She also loves playing with her cat.

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