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Global warming

Reducing Methane Emissions in Ruminants through Genetic Selection

Strategic Insights

— 1 min read

Research published in the Journal of Dairy Science explores the potential of using genomic selection to reduce methane emissions in ruminants. The study, conducted by investigators at AgResearch, found that breeding for low-methane ruminants may change the rumen microbial and milk composition, providing proxy measures of methane for use in selective breeding. The researchers investigated the effect on rumen and milk composition in sheep bred for divergent methane yield and found that milk fatty acid profiles and mid-infrared spectra from milk samples can be used as proxy measures of methane emissions.

Key Takeaways:

  • The study found that milk fatty acid profiles and mid-infrared spectra from milk samples can be used as proxy measures of methane emissions in lactating ewes.
  • The milk fatty acid profiles differed between methane selection lines, with higher PUFA and branched-chain fatty acids levels, and lower total SFA contents in ewes from the low-methane line.
  • The rumen samples from the low-methane ewes had lower proportions of acetate relative to propionate.
  • Predictions of methane were obtained from the rumen VFA and metagenomic profiles and the fatty acid profiles and mid-infrared spectra from milk.
  • These predictions formed the proxy methane measures and were heritable and correlated with the measured methane values.
  • The genetic correlation between proxies and measured methane was between 0.52 and 0.71.
  • The estimated efficiency of indirect selection for methane was higher for the milk sample proxies (49%-75%) than the rumen metagenomic profiles (45%-47%) and rumen VFA profiles (12%-38%).

Statistics:

  • 400 genotyped lactating ewes were used in the study.
  • The study lasted for 4 lactation years.
  • 6 weeks post-lambing, rumen and milk samples were collected.
  • The genetic correlation between proxies and measured methane was between 0.52 and 0.71.
  • The estimated efficiency of indirect selection for methane was between 49% and 75% for the milk sample proxies.

Sources:

  • "Milk fatty acids and rumen composition as proxy measures of enteric methane." Journal of Dairy Science, 2025,108(5):5125-5144.
  • https://doi-org.sdpl.idm.oclc.org/10.3168/jds.2024-25876
  • NewsRx. Studies from AgResearch in the Area of Alkanes Published (Milk fatty acids and rumen composition as proxy measures of enteric methane). Global Warming Focus. May 12, 2025; p 3457.

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