An Estimation of Enteric Methane Emissions from Small Ruminants in a Mediterranean Ecosystem

Prediction of CH4 emissions from sheep and goats was obtained using specific regional CH4 conversion rates (Ym). The IPCC 2019 Guidelines for National Greenhouse Gas Inventories Tier 2 methodology was followed. Results were compared with those derived from the application of the common Ym values proposed by IPCC (2019). Both approaches were applied to obtain a regional inventory of CH4 emission from small ruminants in a semiarid Mediterranean area of Southern Spain. Average regional Ym values of 5.79 kJ/100 kJ GE intake (SD ± 0.43) and 5.17 kJ CH4/100 kJ GE intake (SD ± 1.38) were obtained for sheep and goats, respectively. The CH4 emission factors (EF, kg CH4/head/year) estimated for mature sheep and growing lambs (8.2-10.5 and 5.8, respectively), based on the specific Ym rate were on average a 15.7% lower than those calculated according to the IPCC (2019) Ym value. The CH4 EF for goats (8.3-9.9, 7.4 and 4.6 kg CH4/head/year, in the adult female, mature male and growing animals, respectively), estimated with the regional specific Ym rate, were somewhat lower (6.4%) than those based on the IPCC Ym rate. Taking 2019 as reference year, total enteric CH4 emissions from the small ruminant population in Southern Spain attain 24.5 ktCH4/year. The CH4 emitted corresponds to 281.4 and 249.4 ktCO2-eq/year for sheep and goats, respectively.

Full Text: PDF     DOI: 10.15640/jaes.v10n2a6