AUTHOR=Lkhamaachin Altantsetseg , Sukhbaatar Lkhagvatseren , Nyam-Osor Nyamsuren , Galaaraidii Otgondemberel , Cheng Yanfen , Norovsambuu Togtokhbayar , Janchivlamdan Choikhand , Amarsanaa Munkhtuya , Bayaraa Baasanjalbuu , Sukhbaatar Jigjidpurev , Zhang Ming-Zhi , Sukhbaatar Otgonpurev 
  
TITLE=Enteric methane emission factors for sheep in Mongolian extensive grazing systems: a Tier 2 approach
  
JOURNAL=Pastoralism: Research, Policy and Practice
  
VOLUME=Volume 16 - 2026
  
YEAR=2026
  
URL=https://www.frontierspartnerships.org/journals/pastoralism-research-policy-and-practice/articles/10.3389/past.2026.15693
  
DOI=10.3389/past.2026.15693
  
ISSN=2041-7136
  
ABSTRACT=Methane emissions from livestock are a significant contributor to agricultural greenhouse gas outputs, yet region-specific emission factors are often lacking for nomadic pastoral systems. This study determined annual enteric methane emission factors for sheep across three major agro-ecological zones of Mongolia: Desert-steppe, steppe, and forest-steppe, considering animal sex and age categories. Animal performance data were collected for adult males (>3 years), adult females (>3 years), young sheep (1–2 years), and lambs (<1 year). According to the IPCC Tier 1 methodology, the default emission factor for adult sheep is 5 kg CH4/head/year, while lamb values are estimated at approximately 2 kg CH4/head/year. Nevertheless, these generalized values fail to capture country-specific differences in animal productivity, diet quality, seasonal feed availability, and grazing management, thereby introducing significant uncertainty into national greenhouse gas inventories. Results showed that females consistently exhibited higher emission factors than males, with values ranging from 6.0 to 6.1 kg CH4/head/year, compared to 5.40–5.45 kg CH4/head/year for males. Young sheep emitted between 4.3 and 4.9 kg CH4/head/year, while lamb emissions were lowest at 1.6–1.8 kg CH4/head/year. These findings provide updated, region-specific methane emission factors for Mongolian sheep, supporting the refinement of national greenhouse gas inventories and climate change mitigation strategies.