Methane emission factors and carbon fluxes from enteric fermentation in cattle of Nepal Himalaya

Methane release from enteric fermentation and manure management of domestic water buffalo in Nepal

Methane (CH₄) emission in livestock arises from enteric fermentation (EnF) and manure management (MM). This study develops the country-specific CH₄ emission factors (EFs) in both EnF and MM for domestic water buffalo (Bubalus bubalis) and estimates total CH₄ emission in Nepal using Intergovernmental Panel on Climate Change (IPCC) Tier 2 methodology. Seasonal field data were collected on morphological characteristics, feed characteristics, and manure management practices of the buffalo. The buffalo population was divided into five age groups, and at least 35 buffalo individuals were measured from each age group in the Hilly and Plain regions of Nepal in the winter and summer seasons. Buffalo adult male (BAM) had the highest body weight of 530 ± 53 kg in the plain region and 514 ± 65 kg in the Hill region. Similarly, the weight of buffalo calf (BC) was 91 ± 25 kg in the plain region and 77 ± 26 kg in the Hill region. For different age groups of buffalo, EnF EFs ranged from 34 ± 8 to 90 ± 10 kg CH₄ head^-1 year^-1 and MM EFs ranged from 2.5 ± 0.5 to 7.5 ± 0.5 kg CH₄ head^-1 year^-1. The estimated EnF and MM EFs of buffalo were not statistically different by region (p > 0 .05). The total CH₄ flux from buffalo was 347.8 Gg year^-1 in Nepal, contributing 322.2 Gg year^-1 from EnF and 25.6 Gg year^-1 from MM. The country-specific EFs are highly recommended for precise computing of the national emissions and carrying out mitigation action.

Can the Framing of Climate Mitigation Actions into Government Policies Lead to Delivering Them? - Insights from Nepal's Experience

Many low-income countries (LICs), including Nepal, endeavour to deliver climate mitigation by reducing greenhouse gas (GHG) emissions and achieving more sustainable resource consumption. However, their prospects of delivering on such goals alongside the rapid structural changes in the economy prevalent in the LICs are not clear. This research aims to better understand the underlying complexity in the linkage between the framing of climate mitigation actions into government policies and the prospects for their delivery. We use critical discourse analysis, post-structural discourse analysis, and thematic analysis of textual data corpus generated from government policies (n = 12) and semi-structured interviews (n = 12) with policy actors, such as government policymakers and private sector and non-government organisations' representatives. We also develop energy and material consumption and GHG emissions models to predict their values up to 2050 via the R tools and machine learning algorithms that validate the accuracy of models. Our findings suggest that the social context of policymaking creates a knowledge structure on climate mitigation which is reflected in government policies. The policy actors and their institutions exchange their ideas and interests in a deliberative and collaborative environment to prioritise policies for the energy, forest, and transport sectors to deliver climate mitigation actions in Nepal. However, the energy sector, together with the agriculture sector, has insufficient climate mitigation actions. Reflecting on the high proportion of biomass in the energy mix and the rapid rise in fossil fuel and energy consumption per capita-both of which are driven by the remittance inflows-this research suggests measures to reduce these in an absolute sense.

Characterization and mitigation option of greenhouse gas emissions from lactating Holstein dairy cows in East China

BACKGROUND

This study investigated greenhouse gas (GHG) emission characteristics of lactating Holstein dairy cows in East China and provided a basis for formulating GHG emission reduction measures. GreenFeed system was used to measure the amount of methane (CH₄) and carbon dioxide (CO₂) emitted by the cows through respiration. Data from a commercial cow farm were used to observe the effects of parity, body weight, milk yield, and milk component yield on CH₄ and CO₂ emissions.

RESULTS

Mean herd responses throughout the study were as follows: 111 cows completed all experimental processes, while 42 cows were rejected because they were sick or had not visited the GreenFeed system 20 times. On average, lactating days of cows was 138 ± 19.04 d, metabolic weight was 136.5 ± 9.5 kg, parity was 2.8 ± 1.0, dry matter intake (DMI) was 23.1 ± 2.6 kg/d, and milk yield was 38.1 ± 6.9 kg/d. The GreenFeed system revealed that CH₄ production (expressed in CO₂ equivalent, CO₂-eq) was found to be 8304 g/d, [Formula: see text]/DMI was 359 g/kg, [Formula: see text]/energy-corrected milk (ECM) was 229.5 g/kg, total CO₂ production (CH₄ production plus CO₂ production) was 19,201 g/d, total CO₂/DMI was 831 g/kg, and total CO₂/ECM was 531 g/kg. The parity and metabolic weight of cows had no significant effect on total CO₂ emissions (P > 0.05). Cows with high milk yield, milk fat yield, milk protein yield, and total milk solids yield produced more total CO₂ (P < 0.05), but their total CO₂ production per kg of ECM was low (P < 0.05). The total CO₂/ECM of the medium and high milk yield groups was 17% and 27% lower than that of the low milk yield group, respectively.

CONCLUSIONS

The parity and body condition had no effect on total CO₂ emissions, while the total CO₂/ECM was negatively correlated with milk yield, milk fat yield, milk protein yield, and total milk solids yield in lactating Holstein dairy cows. Measurement of total CO₂ emissions of dairy cows in the Chinese production system will help establish regional or national GHG inventories and develop mitigation approaches to dairy production regimes.

Breed and Season-Specific Methane Conversion Factors Influence Methane Emission Factor for Enteric Methane of Dairy Steers

This study determined the breed and the season-specific methane (CH4) conversion factor (Ym) and the emission factor (EF) for the enteric CH4 of dairy steers. The Ym values for Holstein and Jersey steers at different seasons were calculated using the IPCC 2006 equations by incorporating the input and/or output value of the chemical composition of feed, methane production, methane yield, dry matter intake, and methane energy emission. EFs were categorized into five types depending on the 2019 refinement to the IPCC 2006 Tier 2 equations used. EFA was calculated from Equation 10.21A (New), while other EFs were estimated from the Equation 10.21 which were designated according to the gross energy intake (GEI) and Ym as EFB (GEIi and Ym), EFC (GEIii and Ym), EFD (GEIii and Ym (6.3)), and EFE (GEIii and Ym (4.0)). The calculated overall Ym for Holstein and Jersey steers were 4.90 and 7.49, while the recorded EF of group EFA were 56.44 and 67.42 kg CH4/head/year for Holstein and Jersey steers, respectively. For Holstein steers, EFD was overestimated (75.91 vs. 48.20~58.15), while in Jersey steers, the EFF underestimated the EF (kg CH4/head/year) compared to others (40.15 vs. 63.24~73.28) (p < 0.05). Mixed analysis revealed that the breed influenced EFs of all the EF groups, while the season, and the breed × the season influenced EFs of group EFC, EFD, and EFF. The overall results recommended using the breed-specific Ym for the estimation of the EF for enteric methane in dairy steers.