Abstract
Greenhouse gas emissions from animal production are substantial contributors to global emissions. Therefore Carbon Footprints (CF) were introduced to compare emissions from various foods of animal origin. The CF for food of animal origin depends on a number of influencing factors such as animal species, type of production, feeding of animals, level of animal performance, system boundaries and output/endpoints of production. Milk and egg yields are more clearly defined animal outputs of production than food from slaughtered animals. Body weight gain, carcass weight gain, meat, edible fractions of carcass or edible protein are measurable outputs of slaughtered animals. The pros and contras of various outcomes under special consideration of edible protein are discussed in this paper.
Generated Summary
This review article examines the complex relationship between animal agriculture and its environmental impact, focusing on the methodology of calculating carbon footprints (CF) for food products of animal origin. The study aims to identify the most suitable criteria for measuring animal yields and assess the influence of various factors along the food chain on greenhouse gas (GHG) emissions. The research explores the significance of animal yields and edible protein, and their measurement within the context of sustainable animal husbandry. The core methodology involves analyzing the factors influencing CFs for foods such as milk, eggs, and meat, and fish. It evaluates the impact of factors including animal species, production methods, feeding practices, and system boundaries. The study highlights the importance of understanding GHG emissions from the perspective of climate change and reduction potentials, and considers carbon dioxide, methane, and nitrous oxide. The study emphasizes the need for standardized methodologies and clear system boundaries to allow comparison of results across different studies and settings.
Key Findings & Statistics
- Greenhouse gas emissions from animal production are substantial contributors to global emissions.
- Livestock production contributes about 18% to the global anthropogenic GHG emissions (Steinfeld et al., 2006).
- Animal agriculture is responsible for 8–10.8% of global GHG emissions (O`Mara, 2011).
- Livestock farming contributes to global warming with about 10% of total GHG emissions from the EU-27 (Lesschen et al., 2011).
- The global dairy sector contributes with 3.0 to 5.1% to total anthropogenic greenhouse gases (FAO, 2010).
- Dairy livestock accounts for only 1.2% of global greenhouse gas emissions (Sevenster and Jones, 2008).
- The highest variation of global GHG emissions from livestock is mentioned by Herrero et al. (2011) with a range from 8 to 51%.
- The CF for milk varies between 0.4 and 1.5 kg CO2eq/kg milk, taking different world regions into account (Table 1).
- The CF for milk varies between 1.3 (Europe and North America) and 7.5 kg CO2eq/kg in sub-Saharan Africa (FAO, 2010).
- The CF for milk varies between 0.4 and 1.5 kg CO2eq/kg milk, taking different world regions into account. (Table 1)
- The CF for milk varies between 1.3 (Europe and North America) and 7.5 kg CO2eq/kg in sub-Saharan Africa (FAO, 2010).
- The CF for milk varies between 0.4 and 1.5 kg CO2eq/kg milk, taking different world regions into account. (Table 1)
- The CF for beef cows can have the highest values (Table 2).
- The IPCC [2] recommended GHG factors for CO2 (1), CH4 (23) and N2O (296).
- Between 50 and 80% of the total GHG emissions of food of ruminant origin are due to methane (37,38).
- Agricultural N2O-emissions (from manure and soil) are larger than calculated methane emissions (2.5 versus 2.15 billion t CO2eq/y).
- Around 90 million tonnes CH4 (about 1.9 billion t CO2eq/y) were emitted from gastrointestinal fermentation of ruminants in 2005.
- Model calculations show various endpoints for growing/fattening bulls (150-550 kg body weight) (Table 4).
- The protein content of edible animal products in g per kg edible product is shown in (Table 6).
- Table 7: Influence of animal species, categories and performances on yield of edible protein [84].
- Table 8: Influence of animal species, categories and performances on emissions (per kg edible protein, own calculations).
Other Important Findings
- The study emphasizes the necessity of quantifying and characterizing the yield from animal bodies after slaughtering and processing.
- The study suggests that the production of edible protein of animal origin can be considered a main objective of animal husbandry in many countries.
- The article discusses the importance of setting system boundaries in CF calculations, including emissions from land use, equipment, transport, processing, and waste management.
- The review suggests that the best way to measure the yield of slaughtered animals is by measuring carcass weight or weight gain (warm or cold) because this weight can be measured in the abattoir.
- The study suggests that the production of edible protein should be clearly defined as one endpoint, and should be compared.
- The study also suggests that protein intake is accompanied by energy from the protein itself, it should be avoided to attribute the CO2 burden to the protein fraction (“edible protein”) exclusively.
Limitations Noted in the Document
- The large range in CF when comparing results of various authors depends on many influencing factors as exemplary shown in Table 1 and Table 2 for milk and beef.
- Methodical and regional differences make it difficult to compare such values, to make conclusions or to give data based advice to policy makers.
- Under consideration of all aspects mentioned above, it is extremely difficult to compare results of LCA from different authors.
- The variability in CF calculations has caused confusion among scientists, policymakers, and the public.
- The article notes that in some cases, specific emissions were excluded from calculations of CF due to data uncertainty.
- The document suggests that the data bases for GHG emissions should be improved, and the animal yields should be made comparable.
- The article mentions that measuring climate-relevant gases in all parts of the food chain is essential, and the lack of such precise measuring can be a limitation.
Conclusion
In conclusion, this review article underscores the importance of accurately assessing the environmental impact of animal agriculture by measuring carbon footprints. The primary objective is to determine the most preferable criteria for measuring animal yields, specifically focusing on the measurement of GHG emissions. This is crucial for understanding the impact of various factors, including animal species, production methods, and feeding strategies. The review recommends the need for clear system boundaries and standardized methodologies to ensure reliable comparisons across studies. The study emphasizes the role of edible protein as a key objective in animal husbandry. In essence, the research indicates that the adoption of precise, reliable data collection methods is pivotal for the evaluation of the food chain. The article also suggests an alternative approach for nutritional allocation, emphasizing the impact of the protein source in a balanced diet. The research recognizes the need for further investigation and data to ensure a more sustainable and climate-friendly approach to animal agriculture. The findings highlight the importance of understanding the environmental impacts of food production and also propose the evaluation of food chains, and how practices are or are not sustainable.