Generated Summary
This research article, published in the Journal of Sustainable Agriculture, examines the protein-based Greenhouse Gas (GHG) emission intensity for livestock products in Canada. The study compares the GHG emission intensities of beef, dairy, pork, and poultry, focusing on emissions per unit of protein produced. The analysis utilizes methodologies developed by the IPCC and other researchers to assess the total GHG emissions from each livestock industry. The researchers use an assessment approach, looking at GHG emissions and emission intensities from each production system by comparing them on the basis of the weight of protein produced. The study aims to provide a comprehensive understanding of the environmental impacts of different livestock production systems, especially considering the role of protein in the human diet. The study utilizes census records and other relevant data to track total GHG emissions and GHG emission intensities from each production system to track changes in livestock populations and improved productivity. The overall goal of the paper is to compare the GHG emission intensities for the four major Canadian livestock commodities, with previous analyses not allowing such comparison because the GHG emission intensities of these industries were not all based on the same production unit.
Key Findings & Statistics
- The protein-based emission intensity for beef was almost four times as high as the GHG emission intensity for milk production.
- The emission intensities of pork production were lower than the emissions from milk production because of lower CH4 emissions.
- Broilers had the lowest GHG emission intensity of all five livestock commodities.
- The protein content of animal flesh has been determined as percentages of muscle tissue, fat-trimmed meat, and the fat-trimmed carcass.
- The GHG emissions for the three major GHGs presented in Table 1 show major differences among the total emissions from the four livestock industries and between eastern and western Canada.
- Western beef was the dominant livestock farming system in Canada in 2001.
- The dairy industry was the second highest source of GHGs and the highest eastern Canadian source among the livestock industries.
- At 285 days (9.5 months) for cattle and 114 days (3.8 months) for hogs, cattle have a much longer gestation period than do hogs.
- Hogs can give birth to between 6 and 14 offspring per litter.
- The protein to live weight index (%) for the three major meat livestock types: Beef: 8.3%, Pork: 9.8%, Poultry: 10.1%.
- In all four industries and both regions, fossil CO2 was the lowest source of GHGs.
- The highest protein to LW ratio is for broilers, while beef had the lowest ratio.
- For all GHGs Canada-wide, the intensity for beef was almost four times as high as the GHG emission intensity for milk production.
- The emission intensities of pork production were similar to those of the dairy industry for N2O, but higher for CO2 and lower for CH4.
- Broilers had the lowest GHG emission intensity of all the livestock commodities.
- In 2001, the estimated GHG emissions for beef were 137.5 kg CO2e/kg protein in Eastern Canada and 115.8 kg CO2e/kg protein in Western Canada.
- For pork, the GHG emissions were 25.3 kg CO2e/kg protein in Eastern Canada and 24.8 kg CO2e/kg protein in Western Canada.
- In eggs, the GHG emissions were 9.9 kg CO2e/kg protein in Eastern Canada and 12.3 kg CO2e/kg protein in Western Canada.
Other Important Findings
- The differences in GHG emission intensity between ruminant and non-ruminant digestion is not the only concern with cattle, but rather the slow and inefficient means of reproduction of beef cattle compared with the other animal types.
- Enteric methane is a significant contributor to the difference between dairy and pork.
- The GHG budget analysis showed that the components of the beef industry in Canada cannot be analyzed on their own because of the flow of animals among the different levels of the beef production industry.
- The fossil CO2 emission intensities showed surprisingly little variation among the five commodities.
- The study found that methane is not the main factor with the emission intensity of ruminant agriculture.
- The GWP accounting period for methane from 100 to 20 years would make the range in protein-based emission intensities even greater.
- Reducing the GWP accounting period for methane from 100 to 20 years would make the range in protein-based emission intensities even greater.
- The hog emission intensity would also double, from 25 to 51 kg CO2e/kg protein.
- The GHG emission intensity for eggs would increase moderately, from 22 to 29 kg CO2e/kg protein and the broiler emission intensity would increase only slightly from 11 to 12 kg CO2e/kg protein.
- The results demonstrate that the impacts from particular types of beef operations cannot be considered in isolation of other aspects of the industry.
Limitations Noted in the Document
- The study’s focus on GHG emissions from livestock production does not account for soil carbon sequestration, which could slightly reduce the beef and dairy numbers.
- The analysis was restricted to only one year.
- The study did not fully account for the full impact of CH4 emissions.
- The emission intensities for the two carcass-based commodities (beef and poultry) were reduced slightly at the expense of the milk and egg emission intensity indicators.
Conclusion
The study’s primary conclusion emphasizes the importance of comparing the GHG emission intensities across different livestock types, with beef showing significantly higher intensities than other commodities. “For all GHGs Canada-wide, the intensity for beef was almost four times as high as the GHG emission intensity for milk production, the next highest protein-based emission intensity.” The analysis suggests that non-ruminant industries generally appear to be better protein sources in terms of GHG emissions than the two ruminant livestock systems, with beef standing out as particularly problematic. The study highlights the slow reproduction rate of beef cattle as a critical factor, along with the sector’s reliance on enteric methane emissions. The document suggests that “the real protein-based GHG emission intensity of dairy would actually be lower than shown in Table 3,” and that the emissions are lower from poultry production than from the beef and dairy sectors. The analysis also points out that the current GWP accounting period for methane might underestimate its impact and highlights the need for a shorter GWP accounting period, which would further increase the range in protein-based emission intensities. The analysis underscores the need for a nuanced approach to assessing the environmental impact of livestock farming. The data shows that “the results of this study give strong indication that both poultry industries, particularly broilers, should have a stronger role to play in the future of Canadian livestock production with respect to reducing the sector’s GHG emissions.” In summary, reducing the GHG budget of the sector may best be found in a realignment of the land resources devoted to livestock farming.