Comparison of Tier 1 and 2 methodologies for estimating intake and enteric methane emission factors from smallholder cattle systems in Africa: A case study from Ethiopia

These datasets include enteric methane emission factors derived using the Common Commonwealth Scientific and Industrial Research Organization (‘CSIRO’) and Intergovernmental Panel on Climate Change (IPCC) Tier 2 methods. The activity data collected includes the live weight (LW) measurements of cattle in 113 smallholder farms from different agro-ecological zones collected between February 2020 to January 2021 i.e., five LW measurements at months 0, 3, 6, 9, 12, live weight change for different periods, body condition scoring and physiological status referred here as "Activity data". The animal performance data together with feed quality data were used to predict the energy requirements of the animals. The animals were grouped by age and sex; adult females (>3 years), adult males (intact and castrates) (> 3 years), heifers (1-3 years), young Males (1-3years), and calves (both sexes, <1year).

Estimation of daily methane production (DMP) conducted by programming the equations for ‘CSIRO’ and IPCC Tier 2 methods in Microsoft Excel. The estimations for individuals were made on a seasonal basis. The weighted average of seasonal DMPs was multiplied by 365 to obtain the annual emission factor of enteric methane production.

Feed basket and digestibility calculated_NorthShewa_Ethiopia_2020 to 2021contain information on feedstuffs available and their contribution to feed baskets per agroecological zones in North Shewa. It also shows the average dry matter digestibility for each season. Milk quality data North Shewa_Ethiopia_2020 to 2021 contains information on seasonal milk quality of milk analyzed on pooled milk samples at the household level. Milk yield data North Shewa_Ethiopia_2010 to 2021 contains information on the daily milk yield of lactating cows recorded by farmers on a daily basis.

Supplementary material North Shewa Ethiopia contains results in tabular form and figures to support the justification of findings. Table S1: Seasonal mean live weights change (LWC, g/day) of different classes of cattle: (females, males (intact and castrates), heifers, young males, and calves) from two agro-ecological zones (AEZ) of North Shewa zone, Ethiopia; Table S2: Net energy requirement (MJ/head/day) of different classes of cattle from IPCC Tier 2 methodology in the North Shewa zone, Ethiopia; Table S3: Maintenance energy requirement (MJ/head/day) of the different classes of cattle from ‘CSIRO’ Tier 2 methodology in the North Shewa zone, Ethiopia; Figure S1-S6: Plot of live weight versus emission factors for different cattle sub-categories for ‘CSIRO’ and IPCC Tier 2 methodologies.

本数据集包含采用英联邦科学与工业研究组织（Commonwealth Scientific and Industrial Research Organization，缩写CSIRO）以及政府间气候变化专门委员会（Intergovernmental Panel on Climate Change，IPCC）Tier 2方法推导得到的肠道甲烷排放因子。
采集的活动数据涵盖2020年2月至2021年1月期间，来自不同农业生态区的113个小农户农场的牛只活体重（live weight, LW）测量数据，共包含第0、3、6、9、12个月的5次活体重测量结果，还包括不同周期的活体重变化、体况评分以及生理状态，上述数据统称为「活动数据」。
将动物生产性能数据与饲料品质数据相结合，用于预测动物的能量需求。研究按年龄和性别将牛只划分为不同类别：成年母牛（>3岁）、成年公牛（完整公牛与阉割公牛）（>3岁）、青年母牛（1~3岁）、青年公牛（1~3岁）以及犊牛（雌雄均有，<1岁）。
通过在Microsoft Excel中编写CSIRO与IPCC Tier 2方法的计算公式，开展每日甲烷产量（daily methane production, DMP）的估算工作。个体估算按季节维度开展，将季节DMP的加权平均值乘以365，即可得到肠道甲烷生产的年度排放因子。
`Feed basket and digestibility calculated_NorthShewa_Ethiopia_2020 to 2021`数据集包含埃塞俄比亚北谢瓦地区各农业生态区的可用饲料原料及其在饲粮结构中的占比信息，同时提供了各季节的平均干物质消化率数据。
`Milk quality data North Shewa_Ethiopia_2020 to 2021`数据集包含以农户为单位的混合乳样本检测得到的季节牛奶品质相关信息。
`Milk yield data North Shewa_Ethiopia_2010 to 2021`数据集包含农户每日记录的泌乳母牛日产奶量相关信息。
`Supplementary material North Shewa Ethiopia`数据集包含以表格与图形形式呈现的研究佐证结果，用于支撑研究结论的论证。具体包括：
表S1：埃塞俄比亚北谢瓦地区两个农业生态区（AEZ）不同类别牛只（母牛、公牛（完整公牛与阉割公牛）、青年母牛、青年公牛与犊牛）的季节平均活体重变化（live weight change, LWC, g/天）；
表S2：基于IPCC Tier 2方法得到的埃塞俄比亚北谢瓦地区不同类别牛只的净能量需求（MJ/头/天）；
表S3：基于CSIRO Tier 2方法得到的埃塞俄比亚北谢瓦地区不同类别牛只的维持能量需求（MJ/头/天）；
图S1~S6：基于CSIRO与IPCC Tier 2方法绘制的不同牛只亚类别的活体重与排放因子关系散点图。