Comparing the sustainability of grass-fed and grain-finished cattle
Authors: Lindsey Moderski and Lizzy Kysela
Working as part of a UW extension program, we will create a sustainability analysis of grass-fed and grain-finished cattle for cattle producers in the U.S. We will be assessing all parts of the beef production system from birth to slaughter. These two systems vary greatly in environmental, social, and economic sustainability, therefore, it will be our job to provide a balanced overview of all the pillars of sustainability. In this analysis, we will try to capture the diversity of the many cattle production systems across the U.S. We understand that not all producers will be able to implement certain sustainability practices due to economic, geographical, or social constraints. Therefore, with these constraints in mind, we will try to provide possible solutions to help improve the sustainability of these highly varied production systems. Using this website we hope to distribute our findings to producers that are interested in learning about the benefits and burdens of each system.
The goal of this website is to provide cattle producers with information about the differences in sustainability between grass-fed and grain-finished cattle. We investigated all 3 pillars of sustainability in hopes of providing a balanced overview of the advantages and disadvantages of each system. We asked about the differences in GHG emissions and environmental issues, differences in health outcomes, and the economic feasibility of each system. Overall, grass-fed systems had higher global warming potentials, enteric fermentation levels, and reactive nitrogen footprints. Grain-finished beef tended to have higher fossil and energy usage as well as higher emissions from manure than grass-fed. In terms of other environmental issues, we found that grass-fed systems need more land, more water, and can potentially negatively impact biodiversity if pasture is poorly managed. We did not find conclusive results for differences in eutrophication and acidification. When investigating social sustainability, based on current trends we found that feedlots that classify as CAFOs could contribute to the release of pollutants and negatively impact the health of workers, surrounding communities, and consumers. Examining the economic pillar, there is consensus among grass-fed farmers that it is the more profitable system. However, profit varies by grazing system and forage type. We are unable to make a generalized recommendation for system type without understanding the intricacies of each individual farm system.
Agriculture is essential to survival. However, the agricultural industry causes various environmental issues, including the consumption of finite resources, contributions to climate change, the eutrophication of bodies of water from fertilizer runoff, biodiversity losses, the pollution of groundwater, and the creation of air pollutants (Tilman et al., 2001). There are other environmental risks as well that are not encompassed by the previous list. All of the environmental consequences of modern agriculture threaten the ecosystem services provided by the Earth, many of which the agricultural industry is dependent upon. The fact remains that it is likely that the world’s population will reach nine billion. Some strategies for mitigating environmental impacts while producing enough food to feed the global population include sustainable intensification, the use of new technologies such as genetically modified crops, and waste reduction (Godfray et al., 2010). The agricultural industry will need to make changes to both provide for and avoid endangering the future.
Along that same vein, it is undeniable that meat production is an inefficient process that can be extremely taxing on environmental health. In particular, meat production from ruminant animals such as cattle is especially damaging. While decreasing per capita meat consumption may be the most sustainable solution in some regions, meat can also act as a source of necessary nutrients, economic stability, and cultural significance. Moving forward, a strategy for improving the sustainability of cattle production may be to transition away from conventional cattle production to grazing systems.
We will investigate the following questions to compare the sustainability of grass-fed and grain-finished cattle:
- What are the differences in GHG emissions between grass-fed and grain-fed cattle in terms of global warming potential, enteric fermentation, reactive nitrogen loss, fossil fuel and energy usage, and manure management?
- What are the differences in the degree of other environmental problems such as: eutrophication, biodiversity loss, land usage, acidification, and water usage?
- What are the possible social sustainability issues associated with each system? Are there differences in any of the following: contribution to pollution to outside communities, work quality, consumer health, and preservation of cultural and aesthetic ecosystem services?
- Is there a difference in economic sustainability for producers?
We used various databases and search engines to help us find the research articles for this website. These resources include ScienceDirect, PubMed, Web of Science, Google Scholar, and the Oxford Journal of Animal Science database. We also used the reference lists of interesting papers to find more relevant resources.
- What are the differences in GHG emissions between grass-fed and grain-fed cattle in terms of global warming potential, enteric fermentation, reactive nitrogen loss, fossil fuel and energy usage, and manure management?
Table 1: Summary of the results from question 1
Global Warming Potential (GWP)
An LCA in the upper Midwest region of the U.S found that pasture finished cattle contributed 19.2 kg CO2-e per kg of live weight production of GHG emissions compared to feedlot finished cattle that contributed 14.8kg CO2-e per kg of live weight production (26.9 kg CO2 eq per carcass weight) (Pelliter et al., 2010). This difference in GHG emissions is largely due to the amount of time it takes to finish the cattle. Since higher energy diets allow the cattle to gain weight at a faster rate, they are sent to slaughter sooner than cattle in grass-finished systems. Some research also suggests that high concentrate diets are more likely to reduce ruminant ammonia emissions and nitrous oxide emissions from manure. An LCA in the great plains region of the U.S produced similar results when comparing a grass-fed system with a normal operation (NO) in which cattle are fed a higher concentrate diet in backgrounding and feedlot operations (Lupo et al., 2013). The NO GHG emissions were estimated to be 23.0 kg CO2 eq per kg carcass weight and the grass-fed model estimated a 37% increase in GHG emissions. It is also important to note how calculations of GWP can change when we include carbon sequestration. For grass systems in particular, they estimated that GHG emissions decreased 24% when including carbon sequestration (Lupo et al., 2013).
Enteric Fermentation Emissions
The majority of GHG emissions from cattle is methane released through enteric fermentation. Phases of the beef cattle production system in which cattle are raised with high forage diets tend to have greater methane production compared to the phases using grain feed. Particularly the cow-calf parts of production are significant contributors to these emissions. For example, an LCA conducted in Oklahoma, Texas, and Kanas found that the cow-calf phase contributed to 73% of methane emissions of the entire beef system (Rotz et al., 2015). This is because these operations are responsible for raising calves until they are ready to wean and maintaining breeding stock. This means that the animals stay at the operation longer and there is the maintenance of large numbers of cattle. In addition, both heifers and calves tend to be raised on rangeland or pasture where they consume a high roughage diet, increasing enteric fermentation levels. Past the cow-calf phase, there can be various ways cattle are managed and therefore enteric fermentation levels may vary. For example, an LCA in the Northern Great Plains region estimated that grass-fed systems where calves are weaned straight to pasture contributed more to enteric fermentation than the other management practices. Grass-fed systems have a low concentrate diet which typically results in longer finishing times and lower finishing weight. In this particular LCA, enteric fermentation levels were about 24 CO2-e kg carcass weight (Lupo et al., 2013). The other 3 management strategies involved sending the weaned calves to backgrounding and feedlots where the ratio of concentrate to forage was higher. The systems with higher concentrate to forage ratios had enteric fermentation levels of around 15 CO2-e per kg carcass weight (Lupo et al., 2013).
Fossil Fuel and Energy Usage
The burning of fossil fuels and energy usage are great contributors to GHG emissions. The majority of secondary CO2 emissions in the beef industry come from the burning of fossil fuels, machinery usage, fertilizer production, electricity usage, and transportation (Stackhouse-Lawson et al., 2012). Since there are differences in feed production, machinery used, and transportation between grass and grain systems, they contribute in different ways to fossil fuel and energy usage. For example, Tichenor et al. 2017 also investigated fossil fuel usage between grass-fed and confined dairy beef in the northeastern part of the U.S. The fossil fuel depletion attributed to GF and DB was 1.10 and 1.33 kg oil-eq. per kg HCW, respectively. For grass-fed cattle, 75% of fossil fuel depletion was from the production of winter forages which is highly reliant on the use of diesel fuel (Trichenor, et al., 2017). For confined dairy beef, the highest contributor was the production of concentrate feed such as corn and distillers dried grains with solubles (DDGS). These feeds are highly relied upon in terms of finishing beef cattle, but it requires a lot of energy for the drying and treatment processes they go under (Trichenor, et al., 2017). The second highest contributor to fossil fuel depletion energy and transport for confined dairy beef. However, fossil fuel and energy usage can vary greatly depending on geographical location.
Reactive Nitrogen Loss
Nitrogen is lost in the form of ammonia as soon as feces or urine is excreted from the animal and happens until it is deposited in the soil. Incomplete composition in the soil through nitrification and denitrification can create gaseous nitric oxide emissions (Montes et al., 2013). This lost nitrogen can contribute to over-fertilization, acidification, and eutrophication of ecosystems, global warming, and even some human health concerns (Montes et al., 2013). In addition to manure nitrogen, the production of synthetic nitrogen fertilizer also contributes to these issues. Both the cow-calf and feedlot areas of beef production contribute to reactive nitrogen losses. Rotz et al 2013 created a model to simulate the environmental footprint of the U.S. Meat Animal Research Center (MARC) in which they estimated their operation to have an annual reactive nitrogen footprint of beef produced at MARC was 91.7 ± 18.4 g N/kg BW. The cow-calf sector of the operation contributed the most to the reactive nitrogen footprint contributing 61% g N for the operation while the feedlot of this model contributed 33% g N (Rotz et al., 2013). Ammonia emissions contributed 81% of this footprint followed by nitrous oxide and nitrate leaching (9% and 6% respectively (Rotz et al., 2013).
Although the main contributors of GHG emissions come from enteric fermentation, the handling of manure can contribute greatly to emissions of nitrous oxide and methane. Since up to 50% of the N cannot be recovered in the manure, lots of it is lost to the environment as methane and nitrous oxide (Montes et al., 2013). Cattle in feedlots in particular contribute a significant amount of nitrous oxide and ammonia emissions because they are usually cleaned a couple of times a year when animals are marketed, therefore creating conditions in which GHG are emitted from the pen surface (Montes et al., 2013). Rahmen et al 2013 recently reported emissions for ammonia, carbon dioxide, and nitrous oxide from beef feedlot pen surfaces in North Dakota to be 38 g, 17 kg, and 26 g/head per d, respectively. Although most manure from feedlots is sold for agricultural fertilizer, the time it is in the feedlot still contributes to GHG emissions. In terms of grass-fed beef, Pellier et al. 2010 estimated that total GHG emissions from manure in grass-finished systems were about 20.9% compared to feedlot cattle’s manure emissions that contributed 30.4% of total GHG emissions.
2. What are the differences in the degree of other environmental problems such as: eutrophication, biodiversity loss, land usage, acidification, and water usage?
Table 2. Summary of the results for question 2.
Eutrophication occurs when ecosystems are overloaded with fixed nitrogen and phosphates that stimulate algae growth, lead to depleted oxygen availability, and result in dead zones in coastal waters (Vitousek et al., 1997). The eutrophication of waterways and marine systems can be catastrophic to local organisms and the functioning of the ecosystem. Based on the analysis of previous literature, Clark and Tilman (2017) found that grass-fed systems may be connected with increased risk of eutrophication. However, the authors mention that nutrient cycling within pastures may have the potential to reduce eutrophication. Complicating the subject, Tichenor et al. (2017) found that the eutrophication potential effects of each system varied based on the unit considered. When assessing each system per 1 kg HCW, the grass-fed production had larger eutrophication risks. However, calculations made per unit area of land showed the opposite result. In a review by De Vries et al. (2015), four out of seven studies found roughage based diets for beef production had higher eutrophication potentials. This finding contributes to the ambiguity of eutrophication consequences, and more research is necessary.
Biodiversity impacts vary by the quality of pasture management (Franzluebbers et al., 2012). In poorly managed grazing systems, biodiversity suppression is a risk. In well-managed pastures, biodiversity may be sustained or enhanced. The authors outline five critical characteristics to well-managed pastures. These characteristics include high quality forage production, ensuring that pastures are grazed in a manner that leaves enough plant matter for quick recuperation, encouraging a diverse pasture in terms of forage species, allowing the accumulation of soil organic matter, and providing plant cover to minimize nutrient loss. Moving forward, it is important to clarify that possible sustainability benefits of grass-fed beef production depends on the sustainable management of pastures. While this website is focused primarily within the bounds of the United States, it is also important to note that beef production is leading to deforestation in Brazil (Cederberg et al., 2011). This deforestation and habitat loss is causing large losses in biodiversity (Brooks et al., 2002). Overall, beef production and land conversion are causing biodiversity losses, particularly in biodiversity hotspots.
It has been found that grass-fed systems require more land use (Capper, 2012). This is a common consensus found in other literature as well (Clark and Tilman, 2017). Although land requirements for grass-fed systems vary by region, those systems generally require more land (Gerber et al., 2015). Land, especially arable land, is a finite resource. Therefore, it can be argued that more land use is inherently less sustainable. Complicating the matter, there are two main perspectives on land use and conservation. These perspectives include land sparing and land sharing (Phalan et al., 2011). The land sparing ideology iterates that the best path forward is to intensify agriculture on the land that has already been converted. Under this perspective, humanity should extract everything it possibly can from the smallest amount of land, ideally sparing all other land for conservation. On the other hand, land sharing proposes converting more land for agriculture, but using regenerative or the least destructive practices available. This perspective argues that the “spared” land has not been spared from development and the destructive practices used in intensive agriculture can also affect the conserved land. Returning to the matter of land use in beef production, the land sparing perspective would favor conventional grain-based production. However, it is likely that the land sharing view would favor grass-fed beef if the pastures were managed well and biodiversity was encouraged.
In addition to affecting waterways, synthetic fertilizers also lead to the acidification of soils ( Rasmussen et al., 1998). Soil acidification has a multitude of ecosystem impacts such as biodiversity loss, disruption of nutrient cycling, and lowered accessibility to water for plant roots. Similarly to eutrophication, Tichenor et al. (2017) found that grass-fed systems had higher acidifying potential per unit of beef produced, but the results flipped when the systems were analyzed per unit area of land. Adding to the uncertainty, De Vries et al. (2015) found that two out of five examined studies reported higher acidification potentials for roughage based systems. Because the consequences of acidification can be debilitating to water and soil health, more research is necessary to definitively conclude which production systems have the lowest risks.
Depletion of water resources is a growing concern, and beef production is known to be especially taxing on water supplies (Gerber et al., 2015). In general, livestock production is responsible for 29 percent of the global agricultural water footprint (Mekonnen and Hoekstra, 2012). Beef production is estimated to account for one third of the total livestock impacts. There is evidence that grass-fed systems consume more water than conventional systems for every 1.0 x 10^9 kg of beef produced, 1,957,224 x 10^6 Liters compared to 485,698 x 10^6 Liters (Capper, 2012). This is a large difference in water use. In a paper by Guyader et al. (2016), the authors detail the regionality of pasture and forage type. Water consumption and pasture resilience varies greatly by location and growing season.
3. What are the possible social sustainability issues associated with each system? Are there differences in any of the following: contribution to pollution to outside communities, work quality, consumer health, and preservation of cultural and aesthetic ecosystem services?
Table 3: Summary of results from question 3
Feedlots and contribution to pollution
Over the past several decades, smaller farms have been replaced with concentrated animal feeding operations (CAFO) as a way to cope with the increased demand for animal protein. Many beef cattle feedlots can be qualified as CAFOs. Across species, CAFOs have been studied in terms of their potential for pollution into the air and exposure to other biological compounds. Some of the compounds that have been found in or around CAFOs include volatile organic compounds (VOC), bioaerosols, endotoxins, ammonia, and hydrogen sulfide (Von Essen et al., 2005). Beef feedlots in particular produce a very large amount of manure, potentially increasing the amount of pollutants in an environment. Over time, manure will be compacted by machinery or by animals forming a thin surface layer of manure. However, if the manure is not compacted enough, the manure becomes a reservoir for dust that can be suspended into the air through the shearing action of a bovine’s hoof (Von Essen et al., 2005). Interestingly, cattle behavior plays a big role in the amount of dust released into the air. Parnell et al. 1999 showed that the dust concentration was the highest when cattle activity spiked with stable atmospheric conditions and at ground level. With manure being cleaned out of feedlots around 2 times a year, the amount of pollutants released into the atmosphere accumulate.
Is there a difference in work quality between the two systems?
Health issues of people who work in the livestock industry are well documented. Due to exposure to dangerous gases and biological compounds and the physical nature that livestock jobs can require, it is not surprising to see livestock workers being more likely to accumulate health issues. In addition, CAFOs, are very high-density operations with higher concentrations of these contaminants and therefore lead to negative health outcomes for workers. These issues include exposure to zoonotic disease, gastrointestinal issues, and most commonly respiratory diseases (Douglas et al., 2018). Respiratory diseases are one of the main chronic diseases among farmers (Kirkhorn and Garry, 2000). It is thought that bioaerosols and gases cause inflammation and damage to the upper and lower respiratory tract potentially causing respiratory diseases such as asthma, hypersensitivity pneumonitis, organic dust toxic syndrome, chronic bronchitis, and mucous membrane inflammation syndrome (Kirkhorn and Garry, 2000). Another health concern is the transmission of zoonotic diseases from animals to livestock workers. The close contact that some workers have with their livestock increases their risk of exposure to a zoonotic disease. Although exposure to these contaminants and zoonotic agents can potentially occur in both grass-fed and grain-fed parts of production, feedlots with higher concentrations of animals could increase the risk of developing these diseases.
How does each system contribute to the negative health implications for surrounding communities and consumers?
Livestock systems not only can impact the health of their workers, but they can also potentially impact people in surrounding communities and consumers. With the recent increase in CAFOs around the U.S, many have investigated the potentially harmful effects of CAFOs in nearby rural communities. Schultz et al 2019 investigated how the proximity of dairy CAFOs in Wisconsin impacted the rates of allergic reactions and respiratory diseases in nearby communities. They found in communities within 1.5 miles of a CAFO had an increased chance of self-reporting nasal allergies, lung allergies, and asthma. As the distance from CAFOs increased (5 miles from CAFO) the odds of asthma and allergies decreased and lung function increased. This study suggests that CAFOs can be a source of air pollution that can possibly increase the negative health outcomes of surrounding communities.
One of the ways feedlot cattle can negatively impact consumer health is through the spreading of antimicrobial resistance to meat products. The livestock industry has a history of misusing antibiotics by using them to promote growth in animals. The agricultural misuse of antibiotics combined with the overuse of antibiotics in human clinical settings has led to developing multi-resistant strains of bacteria. Cattle finished in feedlots have many pathways of exposure to these bacteria including feedlot soil, water troughs, and feedlot feces. This means that these pathogens could end up in our meat supply or even in our crops due to feedlot fertilizer being used. These findings have bad implications for consumer health because treatment options for these types of bacteria aren’t going to be effective.
Figure 4. The aesthetic value of grasslands. Photo taken from this site.
The preservation of cultural and aesthetic ecosystem services
Considering the importance of pastoral landscapes, there are ecosystem services that grasslands provide to society that are not necessarily encompassed in statistical or economic analyses. For example, “grasslands play important roles in recreation and human aesthetics. Many outdoor activities, such as bird-watching, hunting, walking and general enjoyment of nature, are linked to open landscapes and extended views” ( Hönigová et al., 2012). The employment of managed grazing practices would help maintain the existence of grasslands and the resulting ecosystem services. The cultural and aesthetic benefits of sustainable grazing systems should play a role in weighing the differences between grazing and CAFO-based beef production.
4. Is there a difference in economic sustainability for producers ?
There is a clear consumer price difference between grass-fed and commodity beef (U.S. Department of Agriculture, 2021). The average consumer price per pound of grass-fed beef was consistently higher than the price of commodity beef in March of 2021. While there is a well-documented premium price for grass-fed beef, the question of producer economic results remains. In a survey of grass-fed beef producers, 81% agreed that grass-fed is more profitable (Sitienei et al., 2020). Although, this may stem from the fact that 79% of farmers agreed that they had “ample land suitable for grazing” which emphasizes the importance of regional and farm-level differences in resources in choosing a beef production system. It is also worth noting that 64% of farmers agreed that grass-fed production has lower costs. In another study, it was found that the grazing system employed has large impacts on the profitability of the farm ( Gillespie et al., 2008). Profitability also varies by forage type ( Bhandari et al., 2017). While there seems to be a consensus among grass-fed producers that it is more profitable, factors such as grazing system, forage type, and regional characteristics likely have large economic impacts.
We tried our best to reflect the diversity of U.S cattle production systems by trying to include studies throughout the U.S. However, the results summarized in this website will not fully reflect each farmer’s unique situation and production practices. Since environmental responses vary by region and climatic conditions, it is not possible to come up with a universal conclusion. For example, the environmental impacts of grass-fed beef may vary depending on the type of pasture which is highly dependent on geography and climate. Another limitation is that many of the studies cited used an LCA framework. This methodology tends to have limited scope in terms of where they can conduct their research, so they may not be fully representative of an area’s production system. In terms of social sustainability, there is limited research on the effects of feedlots on public health. Although it is well documented in other species, particularly pork CAFOs, there aren't too many studies with direct links to beef feedlots. In addition, the value of some ecosystem services can not be quantified in our current system. Finally, there could be more investigation of dairy beef’s contribution to environmental issues.
Throughout this project, we discussed the sustainability of both grass-fed and grain-finished cattle systems. We hope this website helped to educate producers about the importance that each system has on not only the environment, but its workers, consumers, and surrounding communities. Moving forward, more research is necessary on the differences in eutrophication and acidification potentials between systems. Although many major sustainability changes may not be possible due to various barriers, we hope that this information helps producers reflect on their available options. The choice between production systems depends on regional differences, grazing system, forage type, and other farm characteristics. Ultimately, each producer knows their farm best.
About the Authors
|Lindsey Moderski||Lizzy Kysela|
|I'm a UW-Madison senior in animal sciences pursuing a master's degree in public health. Throughout my history in the animal science program, the environmental issues of the agricultural industry have always been an interesting topic to explore. The sustainability of grass-fed beef was something that my professors often talked about, but I never got to explore it in detail. This project allowed me to expand my knowledge of the cattle industry and the various types of sustainability issues it has.||I am a UW-Madison junior in environmental sciences working towards a certificate in food systems. At the intersection between the environment and food, livestock production is an important issue. As a result of taking Grassland 370, I thought more about grass-fed beef than ever before. With the opportunity of this project, I was able to dig deeper into the agricultural uses of grasslands.|