Animal performance and feed characteristics data used to estimate the IPCC Tier 2 enteric methane emissions for smallholder livestock systems in Bomet, Kenya

These datasets contains enteric methane emission factors derived using Intergovernmental Panel on Climate Change (IPCC) Tier 2 method. The activity data collected includes the live weight (LW) measurements of cattle in 131 smallholder farms from different agro-ecological zones collected between December 2016 to January 2018 i.e. five LW measurements at month 0, 3, 6, 9, 12, live weight flux (change) for different periods, body condition scoring and physiological status all referred here as "Activity data". The animal performance activity data coupled with feed quality data (dry matter digestibility (DMD) were used to predict the energy requirements of the animals. These energy requirements include for maintenance, LW gain or loss, locomotion and lactation (for lactating animals). The average of the LW per period was calculated and used to estimate the metabolizable energy requirement (MER) for maintenance and MER for locomotion (energy used when walking during grazing). The LW change was used to estimate the MER for LW gain or loss. The animals were grouped by age and sex; Adult females (>2 years), Adult males (>2years), Heifers (1-2years), Young Males (1-2years) and calves (both sexes, <1year). The MER for maintenance, gain or loss and locomotion applied to all animal classes. However, Adult females (>2years) had an additional energy requirement since most at this age group were lactating and therefore part of the energy was used for milk production. The MER for lactation was calculated using average daily milk yield plus predicted calf milk consumptions for dams with calves of 0 to 3.5 months of age, and milk energy derived from measured herd milk quality (butter fat and solid non fat content). It was assumed that calves were tethered around the homestead and therefore MER for locomotion is negligible and not included for calves. A sum of all the MERs was calculated then used together with feed DMD and Gross energy (GE) to estimate the dry matter intake (DMI) that was in turn used to predict the daily methane production (DMP). All calves of 0 to 3.5 months of age were excluded from DMP calculations as it was assumed that their rumen is not fully developed as hence negligible enteric methane was produced. The DMP was converted to emission factor (EF) by multiplying it with 365 days to get an annual enteric methane emission figure. Feedbasket Information_Bomet_Kenya_2016 to 2018 contain information on feedstuffs available and their contribution to feedbaskets per agro-ecological zones in Bomet county. In addition, we had acreage data for each fodder crop, pasture or food crop residue that were fed to the animals, pasture biomass yield for different periods, the feed nitrogen, acid detergent fibre (ADF) and gross energy for the feedstuffs that were used to calculate the proportion of each feedstuff to the the entire feed-basket and the DMD, Nitrogen and GE of the feed-baskets for the agro-ecological zones in Bomet county.

本数据集包含采用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。本研究采集的活动数据包括2016年12月至2018年1月期间，从131个分布于不同农业生态区的小农户农场收集的牛只活体重（live weight, LW）测量数据，具体包含：第0、3、6、9、12个月共5次LW测量结果、不同时期的活体重变化量、体况评分及生理状态，上述数据统称为‘活动数据（Activity data）’。结合饲料质量数据（干物质消化率（dry matter digestibility, DMD）），可预测动物的能量需求，包括维持代谢、活体重增减、运动及泌乳（泌乳动物）所需能量。研究人员计算了各时期的平均活体重，以此估算维持代谢及放牧行走运动所需的代谢能需求（metabolizable energy requirement, MER）；利用活体重变化量估算活体重增减所需的MER。按年龄与性别将牛只分为以下类别：成年母牛（>2岁）、成年公牛（>2岁）、青年母牛（1~2岁）、青年公牛（1~2岁）及犊牛（两性均有，<1岁）。所有动物类群均适用维持代谢、活体重增减及运动所需的MER，但成年母牛（>2岁）存在额外能量需求——该年龄段个体大多处于泌乳期，需将部分能量用于产奶。泌乳所需的MER通过平均日产奶量加上0~3.5月龄犊牛的母牛哺乳消耗量计算，产奶能量来自实测牛群乳品质（乳脂率与非脂固形物含量）。研究假设犊牛被拴在居所周边，其运动所需的MER可忽略不计，因此该参数未纳入犊牛的计算范畴。将所有类别的MER求和，结合饲料DMD与总能（gross energy, GE），可估算干物质采食量（dry matter intake, DMI），进而预测日产甲烷量（daily methane production, DMP）。0~3.5月龄的所有犊牛被排除在DMP计算之外，原因是其瘤胃尚未发育完全，肠道甲烷产生量可忽略不计。将DMP乘以365天得到年度肠道甲烷排放量，由此可转换得到排放因子（emission factor, EF）。‘Feedbasket Information_Bomet_Kenya_2016 to 2018’数据集包含肯尼亚博梅特县各农业生态区的可用饲料种类及其在饲料筐中的占比信息。此外，研究团队还收集了饲喂给动物的各饲料作物、牧草或粮食作物残渣的种植面积数据、不同时期的牧草生物量产量，以及用于计算各饲料在总饲料筐中占比的饲料氮、酸性洗涤纤维（acid detergent fibre, ADF）与总能数据，同时包含博梅特县各农业生态区饲料筐的DMD、氮含量与总能数据。