Feyissa Abraham Abera, Senbeta Feyera, Tolera Adugna, Diriba Dawit, Boonyanuwat Kalaya
College of Agriculture and Natural Resource, Selale University, Fitche, Ethiopia.
College of Development Studies, Center for Environment and Development, Addis Ababa University, Addis Ababa, Ethiopia.
Carbon Balance Manag. 2023 Nov 29;18(1):23. doi: 10.1186/s13021-023-00242-0.
Following global pledges to reduce greenhouse gas (GHG) emissions by 30% by 2030 compared to the baseline level of 2020, improved quantification of GHG emissions from developing countries has become crucial. However, national GHG inventories in most Sub-Saharan African countries use default (Tier I) emission factors (EF) generated by the Intergovernmental Panel on Climate Change (IPCC) to estimate enteric CH emissions from animal agriculture. The present study provides an improved enteric CH emission estimate (Tier II) based on animal energy requirements derived from animal characteristics and performance data collected from about 2500 cattle in 480 households from three smallholder farming systems to represent the common dairy farming in the central highlands of Ethiopia. Using average seasonal feed digestibility data, we estimated daily methane production by class of animal and farming system and subsequently generated improved EF.
Our findings revealed that the estimated average EF and emission intensities (EI) vary significantly across farming systems. The estimated value of EF for adult dairy cows was 73, 69, and 34 kg CH/cow/year for urban, peri-urban, and rural farming systems, respectively. Rural dairy farming had significantly higher emission intensity (EI) estimated at 1.78 CO-eq per kg of fat protein-corrected milk (FPCM) than peri-urban and urban 0.71 and 0.64 CO-eq kg FPCM dairy farming systems, respectively. The EF estimates in this study are lower than the IPCC's (2019) default value for both stall-fed high-productive and dual-purpose low-productive cows.
The current findings can be used as a baseline for the national emission inventory, which can be used to quantify the effects of future interventions, potentially improving the country's commitment to reducing GHG emissions. Similarly, this study suggests that increased animal productivity through improved feed has a considerable mitigation potential for reducing enteric methane emissions in smallholder dairy farming systems in the study area.
在全球承诺到2030年将温室气体（GHG）排放量在2020年基线水平基础上减少30%之后，改进对发展中国家温室气体排放的量化变得至关重要。然而，大多数撒哈拉以南非洲国家的国家温室气体清单使用政府间气候变化专门委员会（IPCC）生成的默认（一级）排放因子（EF）来估算畜牧业的肠道CH排放。本研究基于动物能量需求提供了一种改进的肠道CH排放估算（二级），该能量需求源自从埃塞俄比亚中部高地三个小农养殖系统的480户家庭中约2500头牛收集的动物特征和生产性能数据，以代表常见的奶牛养殖情况。利用平均季节性饲料消化率数据，我们按动物类别和养殖系统估算了每日甲烷产量，随后生成了改进的排放因子。
我们的研究结果表明，估算的平均排放因子和排放强度（EI）在不同养殖系统之间存在显著差异。城市、城郊和农村养殖系统中成年奶牛的排放因子估算值分别为73、69和34千克CH/头/年。农村奶牛养殖的排放强度（EI）显著高于城郊和城市养殖系统，分别估计为每千克脂肪蛋白校正乳（FPCM）1.78千克CO2当量，而城郊和城市养殖系统分别为0.71和0.64千克CO2当量/千克FPCM。本研究中的排放因子估算值低于IPCC（2019年）对舍饲高产奶牛和兼用型低产奶牛的默认值。
当前研究结果可作为国家排放清单的基线，可用于量化未来干预措施的效果，有可能提升该国对减少温室气体排放的承诺。同样，本研究表明，通过改善饲料提高动物生产力在研究区域的小农奶牛养殖系统中具有相当大的减少肠道甲烷排放的缓解潜力。
