Generated Summary
This report presents a life cycle analysis of the greenhouse gas (GHG) emissions arising from ruminant supply chains around the year 2005. The assessment, based on a life cycle assessment (LCA), encompasses the entire livestock production chain, from feed production through to the final processing of products, including transport to the retail distribution point. The study quantifies the main sources of GHG emissions, and estimates GHG emissions for major ruminant products, predominant ruminant production systems, main world regions and agro-ecological zones (AEZs), and major stages in the supply chains. The analysis utilized the Global Livestock Environmental Assessment Model (GLEAM) to represent processes and activities from the production of inputs into the production process to the farm gate, the point at which products and animals leave the farm. The assessment takes a supply chain approach in estimating emissions generated during the production of inputs, crop and animal production, and subsequent transport and processing of the outputs into basic products. The study aimed to identify low-emission development pathways for the livestock sector. The findings show a wide diversity in emission intensity at regional and production system levels, with variations largely driven by differences in production goals, management practices, and the existence of an emission intensity gap.
Key Findings & Statistics
- In 2010, the ruminant sector contributed about 29 percent to global meat production, equivalent to 81 million tonnes, of which 79 percent is from the cattle sector.
- Global milk production in 2010 was 717 million tonnes, with the cattle sector contributing the bulk, about 83 percent of global production.
- The demand for bovine meat, mutton, and milk is forecasted to grow at a rate of 1.2 percent, 1.5 percent, and 1.1 percent, respectively, during the period 2006-2050.
- Globally, ruminant supply chains are estimated to produce 5.7 gigatonnes CO2-eq per annum, representing about 80 percent of the livestock sector emissions.
- Emissions from beef and milk production represent, respectively, 35 and 30 percent of the livestock sector emissions (equivalent to 4.6 gigatonnes CO2-eq).
- The largest source of GHG emissions in ruminant production is methane (CH4) from enteric fermentation, which accounts for about 47 percent of the sector’s emissions and more than 90 percent of the total CH4 emissions.
- Nitrous oxide (N2O) emissions originating mainly from feed production and N deposited during grazing represent 24 percent of the sector’s GHG emissions.
- Emissions from land-use change associated with the expansion of grassland into forest account for 14.8 percent of total emissions related to beef production.
- Average emission intensity for products from ruminants were estimated at 2.8, 3.4 and 6.5 kg CO2-eq/kg fat and protein corrected milk (FPCM) for cow milk, buffalo milk, and small ruminant milk, respectively, and 46.2, 53.4, and 23.8 kg CO2-eq/kg carcass weight (CW) for beef, buffalo and small ruminant meat, respectively.
- Regional emission intensity of milk ranges from 1.6 kg CO2-eq/kg FPCM to 9.0 kg CO2-eq/kg FPCM.
- Emission intensity of beef at a regional level show a great deal of diversity; ranging from 14 kg CO2-eq/kg CW in Eastern Europe and the Russian Federation to 76 kg CO2-eq/kg CW in South Asia.
- The main contribution to the GHG emission profile of milk in developing regions is enteric fermentation while in industrialized regions dominant emissions are largely related to feed production and processing.
- For milk, emission intensities vary from 1.6 kg CO2-eq/kg FPCM in Eastern and Western Europe to 9 kg CO2-eq/kg FPCM in sub-Saharan Africa (Figure 11a).
- Globally, about 79 percent of the beef and 85 percent of cattle milk and 70 percent and 68 percent of the small ruminant milk and meat, respectively, is produced in mixed systems.
- Average emission intensity of buffalo milk from grazing and mixed farming systems is estimated at 3.4 and 3.2 kg CO2-eq/kg FPCM, respectively.
- The emission intensity of buffalo meat from grazing and mixed farming systems is 36.7 and 54.0 kg CO2-eq/kg CW, respectively.
- Globally, small ruminant production of meat and milk is responsible for 428.8 million tonnes CO2-eq, of which 254.4 million tonnes CO2-eq (59 percent) are associated with sheep production and 174.5 tonnes CO2-eq (41 percent) are associated with goat production.
- On average, the emission intensity of small ruminant milk is 6.5 kg CO2-eq/kg FPCM.
- Average emission intensity for small ruminant meat is 23.8 kg CO2-eq/kg CW.
- The range of values around the mean obtained with the uncertainty analysis was 0.9-2.8 kg CO2-eq/kg milk (Figure 35 and Table 20).
- The average emission intensity for beef is 15.6 kg CO2-eq/kg CW (Figure 36 and Table 20).
Other Important Findings
- There are variations in emission intensities across regions and production systems for each commodity driven by differences in production goals (specialized versus non-specialized production) and management practices.
- The variation in emission intensity between the two systems is explained by several factors such as the generally higher slaughter weights, lower age at calving, reduced time to slaughter, and lower mortality rates and better feed quality in mixed farming systems.
- In both dairy and beef herds, N2O emissions amounted to relatively similar proportions of the total carbon footprint – approximately 29 percent of the emissions.
- Cattle production in temperate zones have lower emission intensities.
- The largest source of GHG emissions in ruminant production is methane (CH4) from enteric fermentation.
- Emissions from land-use change (LUC) associated with the expansion of grassland into forest account for 14.8 percent of total emissions related to beef production.
- Key factors influencing emission intensity include productivity, feed digestibility, and herd structure.
- High milk productivity systems in countries such as Israel and Saudi Arabia have low emission intensity (range between 1.2-1.5 kg CO2-eq/kg FPCM for Israel and 1.1-2.0 kg CO2-eq/kg FPCM for Saudi Arabia).
- The contribution to global small ruminant meat production is characterized by a dichotomy between regions; global lamb and mutton production is largely concentrated in Western Europe and Oceania while production of meat from goats takes place in developing regions.
- The value of non-edible by-products is quite volatile and is mainly driven by the value of hides and skins.
Limitations Noted in the Document
- Due to the global scope of the assessment, the approach developed for this study has had to overcome data requirements by relying on some simplifications that result in a loss of accuracy, particularly for systems at lower levels of aggregation.
- LCA also presents significant challenges, particularly when applied to agriculture, such as the data-intensive nature of the method placing limitations on the comprehensive assessment of complex food chains and biological processes.
- The study does not account for changes in C stocks under constant land use management.
- The approach for estimating emissions from LUC is based on the IPCC Tier 1 approach, which may not fully capture the variability in emissions.
- The analysis relies on general assumptions and data, and the results may contain substantial uncertainty.
Conclusion
The study highlights the crucial role of the ruminant sector in global GHG emissions and provides a foundation for identifying and addressing mitigation strategies. A key takeaway is the significant contribution of enteric fermentation, highlighting the need to improve feeding practices and digestibility of diets. Furthermore, optimizing grazing management and reducing land-use change from pasture expansion and feed crop cultivation are essential strategies. The study underscores that low-producing dairy animals and herds with a breeding overhead contribute to higher emissions. Improving animal productivity and health, improving manure management, and improving the efficiency of feed crop production can all contribute to mitigation. The research emphasizes the large emission intensity gap within different production systems and regions. It underscores the role of high-productivity systems in affluent countries, which can contribute to lower emissions. While the study focused on GHG emissions, it acknowledges the need to consider impacts on other environmental dimensions and broader development objectives. The results emphasize the need for a unified approach to assessment of environmental performance along supply chains, with efforts to harmonize approaches and data. This study underscores the need for detailed characterization of the livestock population, highlighting the importance of animal productivity and feed digestibility for reducing emissions. The study also emphasizes the importance of accounting for LUC and highlights the need for improving data quality and incorporating validated models. The insights gained provide a starting point for understanding the sector’s potential for mitigating emissions, highlighting that reducing emission intensity requires complementary analysis. The main finding points to the importance of addressing methane emissions from enteric fermentation, which accounts for a large proportion of the sector’s emissions and suggests that there is room for improvement by implementing practices such as those that improve feeding practices and digestibility of diets, reduce land-use change arising from feed crop cultivation and pasture expansion, improving yields through genetics, feeding practices, and animal health, reducing the use of uncovered liquid manure management systems (MMSs), and improving feed crop production, and adopting these sustainable practices can help in mitigating emissions from the ruminant sector.