We analysed national Tier 2 greenhouse gas (GHG) inventories for dairy and other cattle in ten East and Southern Africa (ESA) countries to evaluate the variation and predictors of enteric methane (CH 4 ) emission factors (eEFs), and highlight priorities for improvement. We compiled 313 eEFs for dairy cows (n = 26) and other cattle (n = 287) using the Intergovernmental Panel on Climate Change (IPCC) 2019 Tier 2 method and country-specific data, and explored relationships between inputs used in IPCC equations and gross energy intake (GEI, MJ head -1 day -1 ) to identify reliable predictors of eEFs. The eEFs for high (80.74 ± 2.19 kg CH 4 head -1 year -1 ) and low productivity dairy cows (62.26 ± 0.97 kg CH 4 head -1 year -1 ) were 6.5 and 4.5% lower than the IPCC Tier 1a default EFs, respectively. Milk yield solely predicted GEI in dairy cows (r 2 = 0.73, RMSEP = 11.8%). The eEF for low productivity other cattle (56.09 ± 1.0 kg CH 4 head -1 year -1 ) was 16% higher than the IPCC Tier 1a default EF. Our eEF for high productivity systems (56.16 ± 1.0 kg CH 4 head -1 year -1 ) was 6% lower than the IPCC eEF of 60 kg CH 4 head -1 year -1 . Bodyweight, average daily gain and energy digestibility explained 87 and 90% of variation in GEI in growing (RMSEP = 8.1%) and young cattle (RMSEP = 14.6%), respectively. These simplified equations are useful for predicting eEFs in cattle, and highlight the priority country-specific data for Tier 2 inventories in the ESA region.
Svinurai et al. (Mon,) studied this question.