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Last reviewed September 2026
Authored by Jeremiah Say

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Enteric Fermentation Emission Factors

Enteric fermentation livestock methane emission factors dataset: IPCC 2006 Guidelines Volume 4 Chapter 10 Tier-1 and Tier-2 defaults with the 2019 Refinement — methane emission factors by species and region, animal-characterisation defaults, nitrogen-excretion rates and typical animal mass, 597 parameters. A subset of the IPCC AFOLU Tier-1 dataset. Source lineage from IPCC Guidelines through the GreenCalculus MasterBrain and REST API/CSV to your livestock methane total.
MB v2026.203 · updated 22 Sep 2026

Ruminant livestock — cattle, buffalo, sheep and goats — ferment feed in a specialised stomach where micro-organisms break down fibrous plant matter and release methane, which the animal mostly belches out. This enteric fermentation is the single largest source of agricultural methane and one of the largest of all agricultural greenhouse gases. A dairy cow emits dozens of times more enteric methane than a pig, and cattle in high-productivity systems differ again from those on marginal forage, so the IPCC provides emission factors that vary by species, region and productivity.

This page publishes the complete IPCC enteric-fermentation parameter set implemented in the GreenCalculus MasterBrain v2026.203 — 597 parameters covering Tier-1 and Tier-2 methane emission factors, the 2019 Refinement regional factors, animal-characterisation defaults, nitrogen-excretion rates (Nex) and typical animal mass (TAM). It is a subset of the IPCC AFOLU Tier-1 emission factors dataset. These factors power the GreenCalculus Enteric Fermentation calculator — see the methodology.

Quick Answer

Enteric methane is a per-head emission factor: annual CH4 = factor × head count. The IPCC Tier-1 global defaults are 138 kg CH4/head/yr for dairy cattle, 64 for other cattle, 8 for sheep and 1.5 for pigs.

SourceIPCC 2006 · Vol.4 Ch.10
Metrickg CH₄ / head / yr
Parameters597 · 16 species
GC ImplementationMasterBrain v2026.203
Part ofAFOLU dataset (DOI)

The IPCC enteric-fermentation model

The IPCC offers two method tiers. Tier 1 assigns a default annual methane emission factor to each livestock category and multiplies by the animal population — simple, and suitable where livestock are not a key national category. Tier 2 builds the emission factor from each herd’s gross-energy intake and a methane-yield fraction (Ym), which requires default characteristics for live weight, feed digestibility, milk yield, draft work and pregnancy — the Tier-2 tables below.

The Tier-1 calculation

CH₄ (kg/yr) = EF (kg CH₄ / head / yr) × N (head)

where EF is the species (and, for cattle and buffalo, region- and productivity-specific) emission factor, and N is the average annual population. Tier-2 derives EF as EF = (GE × Ym/100 × 365) ÷ 55.65, where GE is gross energy intake (MJ/head/day) and 55.65 MJ/kg is the energy content of methane.

Biogenic — but counted

Enteric methane is biogenic (the carbon comes from plants the animal ate), but unlike biogenic CO₂ it is reported in the Scope 1 total, because methane is not part of the fast biological carbon balance. Every emission-factor value below is a raw mass of CH₄; the characterisation, Nex and TAM tables are activity parameters, not emissions. Convert methane to CO₂e with a biogenic-methane GWP only as the final step (AR6 GWP-100 = 27.9; AR5 = 28).

Enteric methane Tier-1 emission factors (by species & region)

The Tier-1 method assigns each livestock category a default annual methane emission factor per head. Values are a raw mass of CH₄ (biogenic) — multiply by the animal population and by a biogenic-methane GWP (AR6 = 27.9) to reach CO₂e. Cattle and buffalo carry region-specific factors; other species use a single global default.

Cattle & buffalo enteric CH₄ Tier-1 aggregate emission factor, by region (kg CH₄ / head / year) IPCC 2006 Vol.4 Ch.10 Tables 10.10–10.11
Region Dairy cattle Other cattle Buffalo
Global 138 64 —
Africa 76 52 81
Asia 78 54 68
Indian subcontinent 73 46 85
Latin America 87 56 68
Middle East 76 60 67
Eastern Europe 93 58 68
Western Europe 126 52 78
North America 138 64 —
Oceania 93 63 —
Cattle enteric CH₄ Tier-1a by productivity system & region (kg CH₄ / head / year) — use where herd productivity is known IPCC 2019 Refinement Vol.4 Ch.10
Region Dairy — high prod. Dairy — low prod. Other — high prod. Other — low prod.
Africa 86 66 60 48
Asia 96 71 43 56
Indian subcontinent 70 74 41 47
Latin America 103 78 55 58
Middle East 94 62 61 55
Other livestock enteric CH₄ Tier-1 emission factor (kg CH₄ / head / year) IPCC 2006 Vol.4 Ch.10 Table 10.10
Livestock category EF (kg CH₄ / head / yr)
Sheep — global aggregate 8
Sheep — high productivity 9
Sheep — low productivity 5
Goats — high productivity 9
Goats — low productivity 5
Swine — high productivity 1.5
Swine — low productivity 1
Pigs — global 1.5
Poultry — global 0
Camels 46
Deer 20
Horses 18
Llamas & alpacas 8
Mules & asses 10
Ostrich 5

2019 Refinement region-specific emission factors

The 2019 Refinement replaces several 2006 defaults with updated, region-specific cattle and buffalo factors, split by high- and low-productivity systems where data allow. Use these in preference to the 2006 aggregates when reporting under the Refinement.

2019 Refinement enteric CH₄ by region — cattle & buffalo (kg CH₄ / head / year) IPCC 2019 Refinement Vol.4 Ch.10 Tables 10.10–10.11
Region Dairy (agg.) Dairy HP Dairy LP Other (agg.) Other HP Other LP Buffalo
Africa 76 86 66 52 60 48 81
Asia 78 96 71 54 43 56 68
Indian subcontinent 73 70 74 46 41 47 85
Latin America 87 103 78 56 55 58 68
Middle East 76 94 62 60 61 55 67
Eastern Europe 93 — — 58 — — 68
Western Europe 126 — — 52 — — 78
North America 138 — — 64 — — —
Oceania 93 — — 63 — — —
2019 Refinement enteric CH₄ — other livestock (kg CH₄ / head / year) IPCC 2019 Refinement Vol.4 Ch.10
Livestock category EF (kg CH₄ / head / yr)
Sheep — high productivity 9
Sheep — low productivity 5
Goats — high productivity 9
Goats — low productivity 5
Swine — high productivity 1.5
Swine — low productivity 1
Camels 46
Deer 20
Horses 18
Llamas & alpacas 8
Mules & asses 10
Ostrich 5

Tier-2 animal-characterisation defaults

Tier-2 estimates methane from each herd’s energy intake, which requires default characteristics for live weight, feed digestibility, milk yield, draft work and pregnancy. These parameters drive the gross-energy calculation; they are not themselves emission factors. Zero-valued parameters are not shipped individually.

Dairy cow defaults, by region

Tier-2 dairy cow characterisation defaults, by region IPCC 2006 Vol.4 Ch.10 Table 10A.1
Region Weight (kg) DE (%) Milk (kg/head/day) Pregnant (%)
Africa & Middle East 275 60 1.3 67
Asia 350 60 4.5 80
Eastern Europe 550 60 7 80
Indian subcontinent 275 55 2.5 50
Latin America 400 60 2.2 80
North America 600 75 23 90
Oceania 500 60 6 80
Western Europe 600 70 16.4 90

Other (non-dairy) cattle defaults, by region & category

Tier-2 other (non-dairy) cattle characterisation defaults, by region & category IPCC 2006 Vol.4 Ch.10 Table 10A.1
Region Category Weight (kg) Wt gain (kg/d) DE (%) Milk (kg/d) Work (hr/d) Pregnant (%)
Africa Bulls (grazing) 275 — 55 — — —
Africa Draft bullocks 275 — 55 — 1.37 —
Africa Mature females 200 — 55 0.3 0.55 33
Africa Mature females (grazing) 200 — 55 0.3 — 33
Africa Young 75 0.1 55 — — —
Asia Mature females (farming) 325 — 55 1.1 0.55 33
Asia Mature females (grazing) 300 — 60 1.1 — 50
Asia Mature males (farming) 450 — 55 — 1.37 —
Asia Mature males (grazing) 400 — 60 — — —
Asia Young 200 0.2 60 — — —
Eastern Europe Mature females 500 — 60 3.3 — 67
Eastern Europe Mature males 600 — 60 — — —
Eastern Europe Young 230 0.4 60 — — —
Indian subcontinent Mature females 125 — 50 0.6 — 33
Indian subcontinent Mature males 200 — 50 — 2.74 —
Indian subcontinent Young 80 0.1 50 — — —
Latin America Mature females 400 — 60 1.1 — 67
Latin America Mature males 450 — 60 — — —
Latin America Young 230 0.3 60 — — —
North America Calves on forage 185 0.9 65 — — —
North America Calves on milk 100 0.9 — — — —
North America Feedlot cattle 415 1.3 75 — — —
North America Growing heifers/steers 265 0.7 60 — — —
North America Mature females 500 — 60 3.3 — 80
North America Mature males 800 — 60 — — —
North America Replacement/growing 375 0.4 60 — — —
Oceania Mature females 400 — 55 2.4 — 67
Oceania Mature males 450 — 55 — — —
Oceania Young 200 0.3 55 — — —
Western Europe Calves on forage 230 0.3 65 — — —
Western Europe Calves on milk 230 0.3 65 — — —
Western Europe Mature males 600 — 60 — — —
Western Europe Replacement/growing 400 0.4 60 — — —

Buffalo defaults, by region & category

Tier-2 buffalo characterisation defaults, by region & category IPCC 2006 Vol.4 Ch.10 Table 10A.2
Region Category Weight (kg) Wt gain (kg/d) DE (%) Milk (kg/d) Work (hr/d) Pregnant (%)
Indian subcontinent Adult females 350 — 55 2.7 0.55 33
Indian subcontinent Adult males 450 — 55 — 1.37 —
Indian subcontinent Young 200 0.15 55 — — —
Other countries Adult females 350 — 55 0.65 0.55 25
Other countries Adult males 450 — 55 — 1.37 —
Other countries Young 200 0.15 55 — — —

Feed-energy & methane-conversion coefficients

Coefficients feeding the Tier-2 gross-energy and methane-yield (Ym) equations: maintenance and activity coefficients, net-energy densities, pregnancy coefficients, and methane conversion factors by feeding system.

Tier-2 feed-energy and methane-conversion coefficients IPCC 2006 Vol.4 Ch.10 Tables 10.4, 10.5, 10.12–10.13
Coefficient Value Unit
Cfi activity coefficient — Cattle/Buffalo — Grazing large areas 0.36 dimensionless
Cfi activity coefficient — Cattle/Buffalo — Pasture 0.17 dimensionless
Cfi activity coefficient — Cattle/Buffalo — Stall 0 dimensionless
Cfi activity coefficient — Sheep — Grazing flat pasture 0.0107 MJ d-1 kg-1
Cfi activity coefficient — Sheep — Grazing hilly pasture 0.024 MJ d-1 kg-1
Cfi activity coefficient — Sheep — Housed ewes 0.009 MJ d-1 kg-1
Cfi activity coefficient — Sheep — Housed fattening lambs 0.0067 MJ d-1 kg-1
NE_g sheep constant ‘a’ — Castrates 4.4 MJ kg-1
NE_g sheep constant ‘b’ — Castrates 0.32 MJ kg-1
NE_g sheep constant ‘a’ — Females 2.1 MJ kg-1
NE_g sheep constant ‘b’ — Females 0.45 MJ kg-1
NE_g sheep constant ‘a’ — Intact males 2.5 MJ kg-1
NE_g sheep constant ‘b’ — Intact males 0.35 MJ kg-1
NE_m coefficient — Cattle/Buffalo (bulls) 0.37 MJ d-1 kg-1
NE_m coefficient — Cattle/Buffalo (lactating cows) 0.386 MJ d-1 kg-1
NE_m coefficient — Cattle/Buffalo non-lactating cows, beef and multi-purpose, and juveniles 0.322 MJ d-1 kg-1
NE_m coefficient — Sheep (lamb to 1 year) 0.236 MJ d-1 kg-1
NE_m coefficient — Sheep (older than 1 year) 0.217 MJ d-1 kg-1
NE_ma diet content — High grain diet (>90% concentrate) 8 MJ kg-1 dry matter
NE_ma diet content — High quality forage (e.g., vegetative legumes & grasses) 7 MJ kg-1 dry matter
NE_ma diet content — Low quality forage (e.g., straws, mature grasses) 4.5 MJ kg-1 dry matter
NE_ma diet content — Moderate quality forage (e.g., mid-season legume & grasses) 6 MJ kg-1 dry matter
Pregnancy coefficient — Cattle and Buffalo 0.1 dimensionless
Pregnancy coefficient — Sheep — Double birth (twins) 0.126 dimensionless
Pregnancy coefficient — Sheep — Single birth 0.077 dimensionless
Pregnancy coefficient — Sheep — Triple birth (triplets) 0.15 dimensionless
Ym CH4 conversion factor — Other cattle and buffalo primarily fed low quality crop residues and by-products 6.5 percent of gross energy intake converted to methane
Ym CH4 conversion factor — Dairy Cows (cattle and buffalo) and their young 6.5 percent of gross energy intake converted to methane
Ym CH4 conversion factor — Feedlot fed cattle (concentrate > 90%) 3 percent of gross energy intake converted to methane
Ym CH4 conversion factor — Other cattle or buffalo — grazing 6.5 percent of gross energy intake converted to methane
Ym CH4 conversion factor — Lambs (<1 year old) 4.5 percent of gross energy intake converted to methane
Ym CH4 conversion factor — Mature Sheep 6.5 percent of gross energy intake converted to methane

Nitrogen excretion rates (Nex)

Nitrogen excretion (Nex) is the annual nitrogen voided per head, the activity driver for manure-management and managed-soils N₂O. Most values are normalised per 1,000 kg animal mass per day — multiply by typical animal mass (below) and days to get annual per-head excretion. These feed the manure-management and agricultural-soils datasets.

Cattle, buffalo & other mammals

Nitrogen excretion rate (Nex) — mammals IPCC 2006 Vol.4 Ch.10 Table 10.19
Livestock category & region Value Unit
Buffalo — N excretion — Africa 0.42 kg N (1000 kg animal mass)-1 day-1
Buffalo — N excretion — Asia 0.44 kg N (1000 kg animal mass)-1 day-1
Buffalo — N excretion — Eastern Europe 0.35 kg N (1000 kg animal mass)-1 day-1
Buffalo — N excretion — India sub-continent 0.58 kg N (1000 kg animal mass)-1 day-1
Buffalo — N excretion — Latin America 0.41 kg N (1000 kg animal mass)-1 day-1
Buffalo — N excretion — Middle East 0.39 kg N (1000 kg animal mass)-1 day-1
Buffalo — N excretion — Western Europe 0.45 kg N (1000 kg animal mass)-1 day-1
Camels — N excretion — All other regions (LatAm + Africa + Middle East + Asia + India sub-continent) 0.46 kg N (1000 kg animal mass)-1 day-1
Camels — N excretion — North America + Oceania + Western Europe + Eastern Europe (collapsed) 0.38 kg N (1000 kg animal mass)-1 day-1
Dairy cattle — Africa (mean) — nitrogen excretion rate 0.44 kg N per 1000 kg animal mass per day
Dairy cattle — Asia (mean) — nitrogen excretion rate 0.44 kg N per 1000 kg animal mass per day
Dairy cattle — Eastern Europe — nitrogen excretion rate 0.42 kg N per 1000 kg animal mass per day
Dairy cattle — Indian Subcontinent (mean) — nitrogen excretion rate 0.65 kg N per 1000 kg animal mass per day
Dairy cattle — Latin America (mean) — nitrogen excretion rate 0.39 kg N per 1000 kg animal mass per day
Dairy cattle — Middle East (mean) — nitrogen excretion rate 0.5 kg N per 1000 kg animal mass per day
Dairy cattle — North America — nitrogen excretion rate 0.59 kg N per 1000 kg animal mass per day
Dairy cattle — Oceania — nitrogen excretion rate 0.72 kg N per 1000 kg animal mass per day
Dairy cattle — Western Europe — nitrogen excretion rate 0.54 kg N per 1000 kg animal mass per day
Deer — N excretion (single global value) 0.67 kg N (1000 kg animal mass)-1 day-1
Fox and raccoon — N excretion (per head per year, source-native) 12.09 kg N head-1 yr-1
Goats — N excretion — All other regions (LatAm + Africa + Middle East + Asia + India sub-continent) 0.34 kg N (1000 kg animal mass)-1 day-1
Goats — N excretion — Eastern Europe 0.44 kg N (1000 kg animal mass)-1 day-1
Goats — N excretion — North America 0.46 kg N (1000 kg animal mass)-1 day-1
Goats — N excretion — Oceania 0.42 kg N (1000 kg animal mass)-1 day-1
Goats — N excretion — Western Europe 0.46 kg N (1000 kg animal mass)-1 day-1
Horses, mules and asses — N excretion — All other regions (LatAm + Africa + Middle East + Asia + India sub-continent) 0.46 kg N (1000 kg animal mass)-1 day-1
Horses, mules and asses — N excretion — Eastern Europe 0.3 kg N (1000 kg animal mass)-1 day-1
Horses, mules and asses — N excretion — North America 0.3 kg N (1000 kg animal mass)-1 day-1
Horses, mules and asses — N excretion — Oceania 0.3 kg N (1000 kg animal mass)-1 day-1
Horses, mules and asses — N excretion — Western Europe 0.26 kg N (1000 kg animal mass)-1 day-1
Mink and polecat — N excretion (per head per year, source-native) 4.59 kg N head-1 yr-1
Other cattle — Africa (mean) — nitrogen excretion rate 0.45 kg N per 1000 kg animal mass per day
Other cattle — Asia (mean) — nitrogen excretion rate 0.38 kg N per 1000 kg animal mass per day
Other cattle — Eastern Europe — nitrogen excretion rate 0.47 kg N per 1000 kg animal mass per day
Other cattle — Indian Subcontinent (mean) — nitrogen excretion rate 0.44 kg N per 1000 kg animal mass per day
Other cattle — Latin America (mean) — nitrogen excretion rate 0.31 kg N per 1000 kg animal mass per day
Other cattle — Middle East (mean) — nitrogen excretion rate 0.56 kg N per 1000 kg animal mass per day
Other cattle — North America — nitrogen excretion rate 0.4 kg N per 1000 kg animal mass per day
Other cattle — Oceania — nitrogen excretion rate 0.46 kg N per 1000 kg animal mass per day
Other cattle — Western Europe — nitrogen excretion rate 0.42 kg N per 1000 kg animal mass per day
Rabbits — N excretion (per head per year, source-native) 8.1 kg N head-1 yr-1
Reindeer — N excretion (single global value) 0.23 kg N (1000 kg animal mass)-1 day-1
Sheep — N excretion — All other regions (LatAm + Africa + Middle East + Asia + India sub-continent) 0.32 kg N (1000 kg animal mass)-1 day-1
Sheep — N excretion — Eastern Europe 0.36 kg N (1000 kg animal mass)-1 day-1
Sheep — N excretion — North America 0.35 kg N (1000 kg animal mass)-1 day-1
Sheep — N excretion — Oceania 0.43 kg N (1000 kg animal mass)-1 day-1
Sheep — N excretion — Western Europe 0.36 kg N (1000 kg animal mass)-1 day-1

Poultry

Nitrogen excretion rate (Nex) — poultry IPCC 2006 Vol.4 Ch.10 Table 10.19
Livestock category & region Value Unit
Chicken (overall) — N excretion — Africa — High PS 1.16 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Africa — Low PS 1.44 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Africa — Mean 1.29 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Asia — High PS 1 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Asia — Low PS 1.62 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Asia — Mean 1.1 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Eastern Europe 0.96 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — India sub-continent — High PS 1.48 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — India sub-continent — Low PS 1.83 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — India sub-continent — Mean 1.62 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Latin America — High PS 1.13 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Latin America — Low PS 2.14 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Latin America — Mean 1.2 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Middle East — High PS 1.27 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Middle East — Low PS 1.79 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Middle East — Mean 1.29 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — North America 1.45 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Oceania 1.42 kg N (1000 kg animal mass)-1 day-1
Chicken (overall) — N excretion — Western Europe 0.99 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Africa — High PS 1.34 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Africa — Low PS 1.58 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Africa — Mean 1.4 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Asia — High PS 1.31 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Asia — Low PS 1.84 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Asia — Mean 1.35 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Eastern Europe 1.12 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — India sub-continent — High PS 1.47 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — India sub-continent — Low PS 2.11 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — India sub-continent — Mean 1.58 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Latin America — High PS 1.21 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Latin America — Low PS 2.39 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Latin America — Mean 1.23 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Middle East — High PS 1.42 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Middle East — Low PS 1.95 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Middle East — Mean 1.43 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — North America 1.59 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Oceania 1.59 kg N (1000 kg animal mass)-1 day-1
Chicken broilers — N excretion — Western Europe 1.14 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Africa — High PS 0.99 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Africa — Low PS 1.34 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Africa — Mean 1.2 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Asia — High PS 0.89 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Asia — Low PS 1.5 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Asia — Mean 1 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Eastern Europe 0.81 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — India sub-continent — High PS 1.6 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — India sub-continent — Low PS 1.7 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — India sub-continent — Mean 1.65 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Latin America — High PS 1.02 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Latin America — Low PS 2.01 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Latin America — Mean 1.17 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Middle East — High PS 1.06 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Middle East — Low PS 1.7 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Middle East — Mean 1.11 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — North America 1.13 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Oceania 1.04 kg N (1000 kg animal mass)-1 day-1
Chicken hens (>=1 yr) — N excretion — Western Europe 0.87 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Africa — High PS 0.7 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Africa — Low PS 1.72 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Africa — Mean 1.29 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Asia — High PS 0.6 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Asia — Low PS 1.91 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Asia — Mean 0.83 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Eastern Europe 0.58 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — India sub-continent — High PS 0.98 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — India sub-continent — Low PS 2.2 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — India sub-continent — Mean 1.63 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Latin America — High PS 0.68 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Latin America — Low PS 2.5 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Latin America — Mean 0.95 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Middle East — High PS 0.74 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Middle East — Low PS 2.03 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Middle East — Mean 0.85 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — North America 0.77 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Oceania 0.76 kg N (1000 kg animal mass)-1 day-1
Chicken pullets — N excretion — Western Europe 0.58 kg N (1000 kg animal mass)-1 day-1
Ducks — N excretion (single global value) 0.83 kg N (1000 kg animal mass)-1 day-1
Ostrich — N excretion (single global value) 0.36 kg N (1000 kg animal mass)-1 day-1
Turkeys — N excretion (single global value) 0.74 kg N (1000 kg animal mass)-1 day-1

Swine

Nitrogen excretion rate (Nex) — swine IPCC 2006 Vol.4 Ch.10 Table 10.19
Livestock category & region Value Unit
Swine (overall) — N excretion — Africa — High PS 0.33 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Africa — Low PS 0.49 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Africa — Mean 0.44 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Asia — High PS 0.54 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Asia — Low PS 0.67 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Asia — Mean 0.61 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Eastern Europe 0.63 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — India sub-continent — High PS 0.63 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — India sub-continent — Low PS 0.71 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — India sub-continent — Mean 0.68 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Latin America — High PS 0.55 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Latin America — Low PS 0.67 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Latin America — Mean 0.59 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Middle East — High PS 0.67 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Middle East — Low PS 0.56 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Middle East — Mean 0.66 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — North America 0.39 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Oceania 0.54 kg N (1000 kg animal mass)-1 day-1
Swine (overall) — N excretion — Western Europe 0.65 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Africa — High PS 0.21 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Africa — Low PS 0.35 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Africa — Mean 0.29 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Asia — High PS 0.32 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Asia — Low PS 0.43 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Asia — Mean 0.37 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Eastern Europe 0.36 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — India sub-continent — High PS 0.37 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — India sub-continent — Low PS 0.47 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — India sub-continent — Mean 0.43 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Latin America — High PS 0.32 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Latin America — Low PS 0.43 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Latin America — Mean 0.35 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Middle East — High PS 0.41 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Middle East — Low PS 0.37 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Middle East — Mean 0.4 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — North America 0.24 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Oceania 0.31 kg N (1000 kg animal mass)-1 day-1
Swine (breeding) — N excretion — Western Europe 0.38 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Africa — High PS 0.39 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Africa — Low PS 0.54 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Africa — Mean 0.49 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Asia — High PS 0.63 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Asia — Low PS 0.76 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Asia — Mean 0.7 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Eastern Europe 0.77 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — India sub-continent — High PS 0.74 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — India sub-continent — Low PS 0.76 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — India sub-continent — Mean 0.76 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Latin America — High PS 0.69 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Latin America — Low PS 0.8 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Latin America — Mean 0.73 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Middle East — High PS 0.75 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Middle East — Low PS 0.6 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Middle East — Mean 0.73 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — North America 0.46 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Oceania 0.72 kg N (1000 kg animal mass)-1 day-1
Swine (finishing) — N excretion — Western Europe 0.76 kg N (1000 kg animal mass)-1 day-1

Typical animal mass (TAM)

Typical animal mass is the default live weight per head used to scale the mass-normalised nitrogen-excretion and energy parameters. Values are regional defaults in kilograms.

Cattle, buffalo & other mammals

Typical animal mass — mammals (kg live weight) IPCC 2006 Vol.4 Ch.10 Table 10A.4–10A.9
Livestock category & region Value Unit
Buffalo — Africa — typical animal mass (live weight) 339 kg
Buffalo — Asia — typical animal mass (live weight) 336 kg
Buffalo — Eastern Europe — typical animal mass (live weight) 467 kg
Buffalo — Indian subcontinent — typical animal mass (live weight) 321 kg
Buffalo — Latin America — typical animal mass (live weight) 315 kg
Buffalo — Middle East — typical animal mass (live weight) 381 kg
Buffalo — Western Europe — typical animal mass (live weight) 509 kg
Camels — Global default — typical animal mass (live weight) 217 kg
Dairy cattle — Africa — typical animal mass (live weight) 260 kg
Dairy cattle — Asia — typical animal mass (live weight) 386 kg
Dairy cattle — Eastern Europe — typical animal mass (live weight) 550 kg
Dairy cattle — Indian subcontinent — typical animal mass (live weight) 285 kg
Dairy cattle — Latin America — typical animal mass (live weight) 508 kg
Dairy cattle — Middle East — typical animal mass (live weight) 349 kg
Dairy cattle — North America — typical animal mass (live weight) 650 kg
Dairy cattle — Oceania — typical animal mass (live weight) 488 kg
Dairy cattle — Western Europe — typical animal mass (live weight) 600 kg
Goats — All other (developing) — typical animal mass (live weight) 24 kg
Goats — Eastern Europe — typical animal mass (live weight) 36 kg
Goats — North America — typical animal mass (live weight) 41 kg
Goats — Oceania — typical animal mass (live weight) 33 kg
Goats — Western Europe — typical animal mass (live weight) 40 kg
Horses — All other (developing) — typical animal mass (live weight) 238 kg
Horses — Eastern Europe — typical animal mass (live weight) 377 kg
Horses — North America — typical animal mass (live weight) 377 kg
Horses — Oceania — typical animal mass (live weight) 377 kg
Horses — Western Europe — typical animal mass (live weight) 377 kg
Mules and asses — Global default — typical animal mass (live weight) 130 kg
Other cattle — Africa — typical animal mass (live weight) 236 kg
Other cattle — Asia — typical animal mass (live weight) 299 kg
Other cattle — Eastern Europe — typical animal mass (live weight) 389 kg
Other cattle — Indian subcontinent — typical animal mass (live weight) 226 kg
Other cattle — Latin America — typical animal mass (live weight) 303 kg
Other cattle — Middle East — typical animal mass (live weight) 275 kg
Other cattle — North America — typical animal mass (live weight) 407 kg
Other cattle — Oceania — typical animal mass (live weight) 359 kg
Other cattle — Western Europe — typical animal mass (live weight) 405 kg
Sheep — All other (developing) — typical animal mass (live weight) 31 kg
Sheep — Eastern Europe — typical animal mass (live weight) 40 kg
Sheep — North America — typical animal mass (live weight) 40 kg
Sheep — Oceania — typical animal mass (live weight) 40 kg
Sheep — Western Europe — typical animal mass (live weight) 40 kg

Poultry

Typical animal mass — poultry (kg live weight) IPCC 2006 Vol.4 Ch.10
Livestock category & region Value Unit
Chicken (broilers + layers) — Africa — typical animal mass (live weight) 0.9 kg
Chicken (broilers + layers) — Asia — typical animal mass (live weight) 1.2 kg
Chicken (broilers + layers) — Eastern Europe — typical animal mass (live weight) 1.3 kg
Chicken (broilers + layers) — Indian subcontinent — typical animal mass (live weight) 1 kg
Chicken (broilers + layers) — Latin America — typical animal mass (live weight) 1.1 kg
Chicken (broilers + layers) — Middle East — typical animal mass (live weight) 0.9 kg
Chicken (broilers + layers) — North America — typical animal mass (live weight) 1.4 kg
Chicken (broilers + layers) — Oceania — typical animal mass (live weight) 1.3 kg
Chicken (broilers + layers) — Western Europe — typical animal mass (live weight) 1.4 kg
Chicken — broilers — Africa — typical animal mass (live weight) 0.8 kg
Chicken — broilers — Asia — typical animal mass (live weight) 0.8 kg
Chicken — broilers — Eastern Europe — typical animal mass (live weight) 1.1 kg
Chicken — broilers — Indian subcontinent — typical animal mass (live weight) 0.8 kg
Chicken — broilers — Latin America — typical animal mass (live weight) 0.9 kg
Chicken — broilers — Middle East — typical animal mass (live weight) 0.7 kg
Chicken — broilers — North America — typical animal mass (live weight) 1.4 kg
Chicken — broilers — Oceania — typical animal mass (live weight) 1.2 kg
Chicken — broilers — Western Europe — typical animal mass (live weight) 1.2 kg
Chicken — laying hens — Africa — typical animal mass (live weight) 1.4 kg
Chicken — laying hens — Asia — typical animal mass (live weight) 1.5 kg
Chicken — laying hens — Eastern Europe — typical animal mass (live weight) 1.9 kg
Chicken — laying hens — Indian subcontinent — typical animal mass (live weight) 1.3 kg
Chicken — laying hens — Latin America — typical animal mass (live weight) 1.4 kg
Chicken — laying hens — Middle East — typical animal mass (live weight) 1.2 kg
Chicken — laying hens — North America — typical animal mass (live weight) 1.5 kg
Chicken — laying hens — Oceania — typical animal mass (live weight) 2 kg
Chicken — laying hens — Western Europe — typical animal mass (live weight) 1.9 kg
Chicken — pullets — Africa — typical animal mass (live weight) 0.7 kg
Chicken — pullets — Asia — typical animal mass (live weight) 0.8 kg
Chicken — pullets — Eastern Europe — typical animal mass (live weight) 1.3 kg
Chicken — pullets — Indian subcontinent — typical animal mass (live weight) 0.6 kg
Chicken — pullets — Latin America — typical animal mass (live weight) 0.7 kg
Chicken — pullets — Middle East — typical animal mass (live weight) 0.6 kg
Chicken — pullets — North America — typical animal mass (live weight) 1.2 kg
Chicken — pullets — Oceania — typical animal mass (live weight) 1.4 kg
Chicken — pullets — Western Europe — typical animal mass (live weight) 1.5 kg
Ducks — Global default — typical animal mass (live weight) 2.7 kg
Turkeys — Global default — typical animal mass (live weight) 6.8 kg

Swine

Typical animal mass — swine (kg live weight) IPCC 2006 Vol.4 Ch.10 Table 10A.5
Livestock category & region Value Unit
Swine (market) — Africa — typical animal mass (live weight) 49 kg
Swine (market) — Asia — typical animal mass (live weight) 58 kg
Swine (market) — Eastern Europe — typical animal mass (live weight) 77 kg
Swine (market) — Indian subcontinent — typical animal mass (live weight) 59 kg
Swine (market) — Latin America — typical animal mass (live weight) 65 kg
Swine (market) — Middle East — typical animal mass (live weight) 59 kg
Swine (market) — North America — typical animal mass (live weight) 77 kg
Swine (market) — Oceania — typical animal mass (live weight) 61 kg
Swine (market) — Western Europe — typical animal mass (live weight) 76 kg
Swine — breeding — Africa — typical animal mass (live weight) 100 kg
Swine — breeding — Asia — typical animal mass (live weight) 122 kg
Swine — breeding — Eastern Europe — typical animal mass (live weight) 204 kg
Swine — breeding — Indian subcontinent — typical animal mass (live weight) 121 kg
Swine — breeding — Latin America — typical animal mass (live weight) 143 kg
Swine — breeding — Middle East — typical animal mass (live weight) 118 kg
Swine — breeding — North America — typical animal mass (live weight) 184 kg
Swine — breeding — Oceania — typical animal mass (live weight) 163 kg
Swine — breeding — Western Europe — typical animal mass (live weight) 190 kg
Swine — finishing — Africa — typical animal mass (live weight) 41 kg
Swine — finishing — Asia — typical animal mass (live weight) 49 kg
Swine — finishing — Eastern Europe — typical animal mass (live weight) 59 kg
Swine — finishing — Indian subcontinent — typical animal mass (live weight) 51 kg
Swine — finishing — Latin America — typical animal mass (live weight) 51 kg
Swine — finishing — Middle East — typical animal mass (live weight) 52 kg
Swine — finishing — North America — typical animal mass (live weight) 61 kg
Swine — finishing — Oceania — typical animal mass (live weight) 41 kg
Swine — finishing — Western Europe — typical animal mass (live weight) 61 kg

Application — formula & worked example

The calculation

CH₄ (kg) = EF × N
then CO₂e (kg) = CH₄ (kg) × GWP, where N is the average annual head-count and GWP is the biogenic-methane global warming potential.

Tier-1, global default. A 200-head dairy herd at the global Tier-1 factor (EF = 138 kg CH₄/head/yr): CH₄ = 138 × 200 = 27,600 kg CH₄. At AR6 biogenic GWP-100 (27.9): 27,600 × 27.9 = 770,040 kg CO₂e ≈ 770 t CO₂e per year.

Productivity-differentiated. The same herd in a Latin-American high-productivity system uses the Tier-1a factor 103 kg CH₄/head/yr: CH₄ = 103 × 200 = 20,600 kg → 575 t CO₂e — a 25% lower estimate than the global default. Choosing the factor that matches the herd’s region and productivity is the single biggest driver of accuracy for cattle.

Framework requirements

Enteric fermentation is a Scope 1 agricultural emission for a livestock operation, and the Agriculture (Livestock) line in national inventories.

Where the enteric-fermentation factors apply
Framework Role Basis
IPCC 2006 National Inventories Agriculture — Enteric Fermentation (CRF 3A1) These ARE the Tier-1/2 methods
IPCC 2019 Refinement Updated regional & productivity-split EFs Refines the 2006 enteric method
GHG Protocol Corporate Standard Scope 1 (livestock operations) IPCC methods; GWP per latest assessment

Common reporting errors

  1. Reporting the CH₄ mass as CO₂e. Every emission factor here is a methane mass. Convert to CO₂e with a GWP as the last step, and disclose the assessment (AR5 or AR6).
  2. Applying a fossil-methane GWP. Enteric methane is biogenic — use the biogenic CH₄ GWP (AR6 = 27.9), not the fossil value (28.3).
  3. Excluding enteric methane because it is biogenic. Biogenic CO₂ is a memo item; biogenic methane is counted in the Scope 1 total.
  4. Using a global default where a regional factor exists. Dairy cattle range from 76 (Africa) to 138 (global/North America) kg CH₄/head/yr — nearly a two-fold spread. Match the region and, under the Refinement, the productivity system.
  5. Mixing 2006 aggregates with 2019 productivity-split factors. Choose one basis for the inventory; do not average an aggregate factor with a high/low-productivity factor for the same herd.
  6. Confusing characterisation parameters with emission factors. Live weight, digestibility, Nex and TAM are activity data that feed Tier-2 and the manure/soils N₂O calculations — they are not themselves methane emission factors.
  7. Double-counting manure. Enteric fermentation covers CH₄ from digestion only. Methane and N₂O from stored manure are a separate category — see the manure-management dataset.
  8. Forgetting to weight the population. Use the average annual head-count; herds that turn over within the year (feedlot, broilers) must be population-averaged, not counted at peak.

Methodology, boundaries & uncertainty

What this dataset is. The IPCC enteric-fermentation parameter set — Tier-1 and Tier-2 methane emission factors, the 2019 Refinement regional and productivity-split factors, Tier-2 animal-characterisation defaults, nitrogen-excretion rates and typical animal mass — from IPCC 2006 Guidelines Vol.4 Ch.10 with 2019 Refinement updates, as implemented in the GreenCalculus MasterBrain. Part of the IPCC AFOLU Tier-1 dataset.

Boundary. Methane from enteric fermentation (digestion) only, reported in Scope 1. Excludes methane and N₂O from manure management, N₂O from managed soils, and CO₂ from feed production, energy and machinery. Nitrogen-excretion and typical-animal-mass parameters are included here because they characterise the same herds and feed the downstream manure and soils calculations.

Rounding policy. Values are reproduced at IPCC precision. Emission factors are kg CH₄ per head per year; characterisation parameters carry their own units (kg, %, MJ, kg N per 1,000 kg animal mass per day).

Uncertainty. IPCC assigns Tier-1 enteric factors an uncertainty of roughly ±30–50%; Tier-2 estimates are tighter where country-specific characterisation data are used. Tier-1 defaults suit national and screening estimates; measured or Tier-2/3 factors are expected where livestock are a key category.

Applicability. Regional and global defaults; use the region and productivity system matching the herd, and Tier-2 where energy-intake data are available.

Implementation & provenance chain

  1. Primary source — IPCC 2006 Guidelines for National Greenhouse Gas Inventories, Volume 4 (AFOLU), Chapter 10 (Emissions from Livestock and Manure Management), Tables 10.10–10.11 and Annex 10A, with 2019 Refinement updates.
  2. MasterBrain — each parameter is curated under a stable afolu.enteric.*, afolu.nex.* or afolu.tam.* key with its source reference and GHG scope/category; current version v2026.203 (2026-09-22).
  3. REST & CSV — the /afolu-enteric-factors endpoint projects these rows as JSON; the CSV button below serves the identical set.
  4. Calculators — GreenCalculus agriculture tools read the same keys, so a published inventory and this page cannot diverge.
  5. Update plan — static reference; revalued on a new IPCC refinement to the AFOLU livestock method. Logged in the version history and bumps the dataset version.

Data access — REST API & CSV

The full 597-row dataset is available as a machine-readable REST endpoint and as a flat CSV download — the same rows shown above, versioned and citable.

JSON — REST API
All 597 enteric-fermentation parameters with keys, values, units, gas, GHG scope/category and source references. Cache-Control: max-age=3600; X-GC-Version header signals dataset updates.

/wp-json/greencalculus/v1/afolu-enteric-factors

Open API endpoint →

CSV — flat dataset
Flat CSV of all 597 rows (key, name, value, unit, gas, GHG scope/category, source, note) — ready for spreadsheet import.

Click to generate ↓

Citation guidance

Cite the IPCC primary source. These factors are a subset of the GreenCalculus IPCC AFOLU Tier-1 dataset, which holds the citable DOI — cite the parent dataset, not a separate enteric DOI.

IPCC (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 4: Agriculture, Forestry and Other Land Use, Chapter 10 (Emissions from Livestock and Manure Management), with the 2019 Refinement. Prepared by the National Greenhouse Gas Inventories Programme, IGES, Japan.

IPCC 2006 Guidelines Vol.4 primary citation

Say, Jeremiah (2026). IPCC AFOLU Tier-1 emission factors (machine-readable). GreenCalculus. Zenodo. https://doi.org/10.5281/zenodo.20621658

Parent dataset DOI — includes the enteric-fermentation subset

Browse the full IPCC AFOLU Tier-1 emission factors dataset, of which this page is a part.

Frequently asked questions

Enteric fermentation is the microbial digestion of feed in the gut of livestock, most importantly in the rumen of cattle, buffalo, sheep and goats. Micro-organisms break down fibrous plant material and produce methane as a by-product, which the animal releases mainly by belching. Because ruminants have a large fermentation chamber, they emit far more enteric methane than monogastric animals such as pigs and poultry.

Cattle, by a wide margin. Dairy cattle carry the highest per-head factor (138 kg CH₄/head/yr global default) because of their high feed intake, followed by other (non-dairy) cattle (64) and buffalo. Sheep (8) and goats (5–9) are an order of magnitude lower per head, and pigs (1.5) and poultry (~0) lower still — though large populations can still make them material.

Use Tier-1 default factors for screening estimates or where livestock are not a key category — a single emission factor per species multiplied by head-count. Use Tier-2 where livestock are a material source and you have herd-level data on live weight, feed quality and productivity: Tier-2 builds the emission factor from gross-energy intake and a methane-yield fraction, using the characterisation defaults on this page as starting values. The 2019 Refinement adds high/low-productivity Tier-1a factors as a middle option.

Raw methane. Every emission factor is a mass of CH₄ per head per year, stored biogenic (with no GWP pre-applied). To reach CO₂e, multiply the total methane mass by a biogenic-methane global warming potential as the final step. This keeps the dataset GWP-neutral so you can apply AR5 or AR6 consistently across your whole inventory.

Use the biogenic-methane GWP, because enteric CH₄ comes from recently-fixed atmospheric carbon in the animal’s feed. Under IPCC AR6 GWP-100 that is 27.9; under AR5 it is 28. Do not use the fossil-methane value (AR6 = 28.3), and always disclose the assessment. See the IPCC AR6 GWP values dataset.

Because they characterise the same herds. Nitrogen excretion (Nex) and typical animal mass (TAM) are livestock parameters the IPCC publishes alongside the enteric factors in Chapter 10; they drive the Tier-2 energy calculation and, more importantly, the downstream manure-management methane and the managed-soils N₂O estimates. Grouping them with the livestock population parameters keeps the animal characterisation in one place. They are activity data, not emission factors.

No — it is a subset. The enteric-fermentation factors here are part of the GreenCalculus IPCC AFOLU Tier-1 emission factors dataset, which carries the single citable Zenodo DOI. This page presents the enteric portion in full with its own machine-readable endpoint and CSV, but for citation you reference the parent AFOLU dataset DOI, not a separate enteric DOI.

The 2019 Refinement splits cattle into high- and low-productivity systems because feed quality and intake — and therefore methane — differ sharply. High-productivity dairy herds eat more and emit more per head in absolute terms, but often less per litre of milk; low-productivity herds on marginal forage emit less per head. Use the split that matches the herd’s management system, and apply it consistently rather than averaging with the aggregate factor.

Version history

Substantive revisions to this dataset reference page
Version Date MasterBrain Summary
1.0 2026-07-20 v2026.59 Initial publication. Complete IPCC 2006 Vol.4 Ch.10 enteric-fermentation parameter set (597 parameters): Tier-1 & Tier-1a methane emission factors by species/region/productivity, 2019 Refinement regional factors, Tier-2 animal-characterisation defaults, nitrogen-excretion rates and typical animal mass. Formula, worked example, framework mapping, 8-item FAQ, REST + CSV access. Subset of the IPCC AFOLU Tier-1 dataset.

Explore the full AFOLU dataset

Enteric fermentation is one part of the IPCC AFOLU Tier-1 emission factors — the parent dataset also covers manure management, agricultural soils, rice cultivation, land-use change, forest land and biomass burning, all with machine-readable access and the citable DOI.

IPCC AFOLU dataset →
IPCC AR6 GWP values →

Primary source. IPCC (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 4: Agriculture, Forestry and Other Land Use, Ch.10 (Emissions from Livestock and Manure Management), Tables 10.10–10.11 and Annex 10A, with 2019 Refinement updates. National Greenhouse Gas Inventories Programme, IGES, Japan. Available at: ipcc-nggip.iges.or.jp. Licence: CC BY 4.0.

Reporting basis. Raw CH₄ mass (kg CH₄ per head per year) and livestock characterisation parameters; Scope 1 agricultural methane. Enteric CH₄ is biogenic but counted — convert to CO₂e with a disclosed biogenic-methane GWP.

GreenCalculus implementation. MasterBrain v2026.203 (2026-09-22). All 597 parameters reproduced cell-for-cell from IPCC 2006 Vol.4 Ch.10 with the 2019 Refinement, verified against the MasterBrain data layer by Jeremiah Say, July 2026. Part of the IPCC AFOLU Tier-1 dataset (DOI 10.5281/zenodo.20621658). Revalued on a new IPCC refinement.

Disclaimer. Published for reference and calculation. Match the region and productivity system to the herd, population-average turnover herds, keep the method tier consistent, and disclose the GWP basis before finalising your methodology.

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