Abstract
This study compared the environmental impact of conventional, natural and grass-fed beef production systems. A deterministic model based on the metabolism and nutrient requirements of the beef population was used to quantify resource inputs and waste outputs per 1.0 × 10º kg of hot carcass weight beef in conventional (CON), natural (NAT) and grass-fed (GFD) production systems. Production systems were modeled using characteristic management practices, population dynamics and production data from U.S. beef production systems. Increased productivity (slaughter weight and growth rate) in the CON system reduced the cattle population size required to produce 1.0 × 10º kg of beef compared to the NAT or GFD system. The CON system required 56.3% of the animals, 24.8% of the water, 55.3% of the land and 71.4% of the fossil fuel energy required to produce 1.0 × 10° kg of beef compared to the GFD system. The carbon footprint per 1.0 × 10º kg of beef was lowest in the CON system (15,989 × 10³ t), intermediate in the NAT system (18,772 × 10³ t) and highest in the GFD system (26,785 × 10³ t).
Generated Summary
This research employed a deterministic model to assess the environmental impact of three beef production systems: conventional (CON), natural (NAT), and grass-fed (GFD). The study’s approach involved quantifying resource inputs and waste outputs per 1.0 × 10⁹ kg of hot carcass weight beef. It compared the environmental impacts of these systems to inform consumers about sustainable dietary choices, considering factors like land, water, and fossil fuel use, along with greenhouse gas emissions. The model was based on the metabolism and nutrient requirements of the beef population and utilized data from U.S. beef production systems. The primary aim was to evaluate the environmental impacts of conventional, natural, and grass-fed beef production, focusing on resource use and greenhouse gas emissions.
Key Findings & Statistics
- The CON system required 56.3% of the animals, 24.8% of the water, 55.3% of the land, and 71.4% of the fossil fuel energy required to produce 1.0 × 10⁹ kg of beef compared to the GFD system.
- The carbon footprint per 1.0 × 10⁹ kg of beef was lowest in the CON system (15,989 × 10³ t), intermediate in the NAT system (18,772 × 10³ t), and highest in the GFD system (26,785 × 10³ t).
- Increased productivity (slaughter weight and growth rate) in the CON system reduced the cattle population size required to produce 1.0 × 10⁹ kg of beef compared to the NAT or GFD system.
- The CON system required 7,046 × 10³ animals in the population to produce 1.0 × 10⁹ kg of beef compared to 8,257 × 10³ animals (a 17.1% increase) and 12,510 × 10³ animals (a 77.5% increase) in the NAT and GFD systems respectively.
- Reducing slaughter weight and growth rate increases the population nutrient requirement of the CON system (228,651 × 10⁶ MJ ME) by 11.5% in the NAT system (254,841 × 10⁶ MJ ME) or 54.6% in the GFD system (353,484 × 10⁶ MJ ME).
- The quantity of arable land available per capita is predicted to decrease, reaching a nadir at 0.15 ha/person in 2050.
- The CON system required 5,457 × 10³ ha of land per 1.0 × 10⁹ kg beef, the NAT system required 22.4% more land (6,678 × 10³ ha), and the GFD system at 80.8% more land (9,868 × 10³ ha).
- The CON system used less fossil fuel energy per 1.0 × 10⁹ kg beef (8,773 × 10⁶ MJ) compared to the NAT (10,304 × 10⁶ MJ, an increase of 17.5%) or GFD (12,290 × 10⁶ MJ, an increase of 40%) systems.
- The GFD system had a carbon footprint of 26,785 t CO2-eq per 1.0 × 10⁹ kg beef, which is an increase of 67.5% compared to the CON system.
- The CON system (399,789 t N/kg beef and 37.190 t P/kg beef) compared to the NAT system (486,683 t N/kg beef and 46,897 t P/kg beef) or GFD system (807,759 t N/kg beef and 76,567 t P/kg beef).
Other Important Findings
- The CON system used fewer animals and less land, water, and fossil fuels to produce a set quantity of beef compared to the NAT and GFD systems.
- The carbon footprint of the CON system was lower than both the NAT and GFD systems.
- The study highlighted the importance of productivity in reducing environmental impact through the “dilution of maintenance” effect.
- The study noted that the GFD system did not include any animals from the dairy industry, which typically finish in feedlots.
- Improvements in growth rate and slaughter weight in the CON system reduced water consumption.
- The GFD system’s higher fossil fuel energy use was attributed to cropping and harvesting practices for conserved forages.
Limitations Noted in the Document
- The study’s model relies on assumptions regarding transportation distances, feed transport, and land use, which could influence the results.
- The GFD system’s water use is sensitive to the assumption that 50% of grassland used to finish cattle is irrigated.
- The study acknowledges that the GFD system did not include any animals from the dairy industry.
- The study did not account for the potential of carbon sequestration by well-managed pastureland in the GFD system due to a lack of data.
- The study highlights that the growth rates used in the model are those predicted by the AMTS Cattle Pro ration formulation software and may not be representative of any specific farm.
Conclusion
The central theme of the research underscores that intensive, feedlot-finishing systems, when combined with technologies that boost animal productivity, are more environmentally efficient in terms of resource use and greenhouse gas emissions per unit of beef. The study’s outcomes reveal that while the GFD system may appeal to consumers, it demands a larger animal population and more land, thus resulting in a higher carbon footprint. The findings emphasize that increasing slaughter weight and growth rate are significant factors in reducing the environmental impact of beef production. The CON system required fewer animals, less water, and less fossil fuel energy to produce a set quantity of beef, and had a lower carbon footprint than the NAT and GFD systems. This research affirms that the productivity-focused strategies within the CON system are environmentally more sustainable. However, this must be considered alongside the societal concerns about intensive farming, with the understanding that all sustainable systems play a part in the industry. The study emphasizes the need to communicate the relative environmental impacts of different beef production systems to stakeholders to sustain a variety of beef products and to provide consumers with a scientific basis for dietary choices. Ultimately, the study implies that both intensive and extensive systems can be sustainable, with the environmental impact varying across different practices and systems. The research supports the idea that all systems have a place within the industry, provided they meet the requirements of sustainability, and it underscores the importance of informed decision-making by consumers and producers.