More and More, Beef (And Less Climate Impact)

Beef, more than any other major food, is frequently called out in discussions of agricultural greenhouse gas emissions. Attempts to reduce the emissions from beef production typically take on one of two approaches: getting people to eat less beef, or inhibiting or capturing emissions of methane produced by bacteria in the gut or manure of cattle. Meaningful work is being done in both of these areas, but betting the farm on this work alone will not yield the emission reduction goals of environmental groups, governments, or even industry stakeholders.

Efforts to change diets have achieved limited success in wealthy countries, and global demand for beef is rising. This is expected to continue as long as a general trend towards economic growth and development continues around the world.

Globally, beef production already occupies more land than any other agricultural product. Meeting rising demand will require either expansion or intensification: clearing new lands (with associated soil carbon loss) or getting more out of current land. Certain production methods and systems under the umbrella of “regenerative agriculture” may be able to produce smaller quantities of beef with low climate impact, but cannot scale to produce climate efficient beef at necessary production levels to meet growing global demand.

For those betting on a technological solution, methods for methane inhibition or capture have the potential to reduce the emissions intensity of beef production. However, even if methane were taken out of the equation, beef production would still remain more emissions intense than pork, chicken, or other proteins, for the simple reason that cattle are relatively inefficient at converting feed into body weight. If global food systems are ever to meet rising global demand for beef in a sustainable way, it will require a direct reduction of greenhouse gas emissions from beef production, and an increase in the efficiency of beef production.

Despite being the most efficient producer of beef in the world, there is still significant room to improve the efficiency of U.S. beef production. A realistic set of productivity improvements could enable U.S. farmers to produce a fifth more beef without increasing greenhouse gas emissions. This would involve improving animal health, reducing mortality rates, and advancing genetics through both selective breeding and new gene editing technologies.

Most notably, an increase of just ten percent in the average efficiency of cattle digestion would reduce the emissions intensity of U.S. beef production by over eight percent. This is achievable through investments in cattle health, disease tracking, research to better understand the nutritional requirements of individual animals and feed additives to improve digestive health. Without investments in research and animal health, natural hazards, such as heat stress from rising temperatures in major beef producing areas, or the avian flu outbreak currently affecting dairy herds, could undo efficiency gains made over the past half-century, worsening rather than ameliorating the climate impact of U.S. produced beef.

Productivity enhancement is often associated with “factory farming” and poor declining animal welfare. Approaching productivity enhancement through the treatment of illness and improved gastro-intestinal health, to the contrary, improves animal welfare within any system. We are a long way from methane-free beef, but combining best-case-scenarios for both methane inhibition and productivity enhancement, the emissions intensity of beef production could be brought to a level similar to that of pork while maintaining the advantage that cattle feed does not directly compete with human feed sources. In the context of global food markets, if an increase in domestic beef production due to improved productivity offsets production in less efficient countries and decreases pressure for deforestation to expand pasture. As a result, the net effect of productivity enhancement in the U.S. on global emissions would be even greater than the direct reduction in emissions intensity.

Beef in America

American farms raise cattle more than any other animal or crop. The gap is not small. Of 1.9 million farms reported in the 2022 U.S. Census of Agriculture, ranging from hobby farms to massive operations, 732,000 (38 percent) reported having cattle, more than twice as many as grew corn (306,000), soybeans (270,000), or raise chickens (262,000), and twelve times the number of farms with hogs and pigs (61,000). The only product category that comes close to the ubiquity of beef cattle (fewer than five percent of farms with cattle are dairy farms) is hay (610,000) and other forms of roughage only fed to ruminants such as cattle, goats, and sheep.

Cattle are especially common on small and mid-sized farms: 45 percent of the 641,000 farms with more than $25,000 in annual sales (but less than $1 million) raise cattle. This is in large part due to the fact that they can live just about anywhere and eat almost anything, transforming rich starches or tough fibers into a valuable and popular protein. Cattle are a cornerstone of American farms nationwide.

Despite their diversity, cattle farmers and ranchers in the United States are remarkably efficient, producing twenty percent of the world’s beef with less than ten percent of the world’s cattle. This productivity advantage is due not only to the availability of high-quality pasture, range, and cropland in the U.S., but also to more than a century of productivity enhancement through genetics, veterinary health, and other advancements. One example: fast growing British cattle breeds such as Angus and Hereford, which exhibit improved maternal and calf health when cross bred, have been widely adopted in most of the U.S. These breeds do not survive well in hot and humid climates such as major cattle raising regions in Brazil and Argentina, where smaller breeds are preferred. In continental Europe, larger but slower growing cattle are preferred, and growth promoting beta-agonists are banned.

Figure 1 shows the total U.S. cattle population alongside beef and dairy production, indexed so 1961 values equal 100. The 1960s and early 70s saw a dramatic increase in beef production, peaking in 1976, a year after the U.S. cattle population reached an all-time high of over 136 million animals. In 2022, U.S. farms produced nine percent more beef and eighty-eight percent more milk than in 1976, with twenty-seven percent (forty million) fewer animals.

Cattle in Brazil, the second largest beef producing country in the world after the U.S., yield barely two-thirds the beef of U.S. cattle (hot carcass weight averaged 245kg in Brazil against 370kg in the U.S. in 2022). Of nations producing a million tons of beef or more, only Canada approaches the U.S. in beef per animal. Cattle in China and the European Union, the third and fourth top beef producers in the world, yielded an average 148 kg and 288 kg of beef per animal in 2022, respectively.

In addition to having the highest yield of beef per animal, U.S. cattle production is also among the least emissions intensive—that is, having relatively low emissions per unit of beef produced—of any nation in the world.

In 2021, the Breakthrough Institute explored the potential of several existing and breakthrough technologies to reduce the emissions from U.S. beef production. The Clean Cow report found that existing technologies to reduce enteric and manure methane emissions, improve feed production and soil carbon sequestration, control disease, and optimize grazing, had the potential to decrease net emissions from U.S. beef production by eighteen percent.

This analysis focuses solely on productivity enhancing developments in cattle production, excluding more efficient production of feed. Unlike practices that reduce cattle emissions directly, such as manure composting and methane-inhibiting feed additives, productivity enhancement decreases the emissions intensity of beef by producing more with the same or fewer inputs.

FAO estimates that the emissions intensity of beef production fell by 38 percent from 1961 to 2022 (Figure 2), while Capper estimated that productivity gains alone reduced the emissions associated with a pound of beef bought in the grocery store by eighteen percent from 1977 to 2007. Though FAO's estimates only include emissions from enteric methane, manure, and emissions from cropland related to feed (leaving out land use change and transportation, among other factors), they attribute the decline in emissions intensity of beef primarily to rising productivity. This has occurred without widespread adoption of practices intended to directly cut emissions.

Improvements in U.S. beef productivity have been built upon both public and private investments in research and development. Artificial insemination has allowed for the rapid adoption of new breeds, such as the British Herefords discussed above. Ongoing work—such as the development of nutrient rich feeds, new treatments for emerging diseases, and even gene-edited cattle that are more tolerant of heat—is required, not only to enhance productivity, but also to avoid backsliding in an ever-changing world.

Here, I examine the emissions impact of several scenarios of increased beef productivity using a model designed and calibrated to be representative of the U.S. beef cattle population and common farming and ranching practices. We find that a modest increase the average feed conversion rate (the amount of weight gained per unit of feed consumed) is the single most effective approach to decreasing the emissions intensity of beef production—a ten percent improvement in the national average feed conversion rate would reduce the emissions intensity of a pound of beef by 8.5 percent, or allow the U.S. to produce the 9.3 percent more beef without increasing emissions. This could be achieved through disease prevention to reduce the rate of growth-stunting illnesses such as bovine respiratory disease, and nutrition improvements to better match the needs of growing cattle—changes also likely to cause a decline in calf and cattle mortality.

A decline of one half in calf and cattle mortality would reduce the emissions intensity of beef production by nearly four percent. If three-fourths of calves were born male, a 3.3 percent decline in beef emissions intensity (or 3.5 percent increase in beef production with constant emissions) is likely.

All told, we calculate that the emissions intensity of U.S. beef production could be reduced by 16.3 percent through reasonable advancements in cattle health, a continuation of historic genetic improvements, and deployment of gene editing technologies already in existence. With lower emissions intensity, the U.S. could produce 19.5 percent more beef without increasing total emissions. An increase in domestic production, if it offsets production expansion elsewhere, particularly among major beef producers in South and Central America, could also reduce global emissions, including from deforestation caused by beef production in the Amazon and other tropical areas.

While productivity enhancement may not have the same potential as widely discussed approaches to producing climate friendly beef, such as the adoption of methane inhibiting feed additives, it will be necessary to fulfill a growing global demand for beef while reducing further damage on the climate and marginal ecosystems. Furthermore, productivity enhancing technologies and practices developed and made available through both public and private investments in agricultural research and development are likely to be adopted by farmers because they are good for business.

It Is Not Enough to Be the Best

It is widely recognized that U.S. beef production has become more efficient and less emissions intensive over the last several decades. Still, beef is by far the most emissions intensive of America’s big three animal-based proteins (beef, chicken, and pork). Estimates of the emissions intensity of the meat of other ruminants, such as lamb and goat, are widely variant but generally fall in a range similar to beef emissions. In the last decade, a great deal of attention has been paid to inhibiting enteric methane production. One anti-methanogenic feed additive has been approved by U.S. regulators to date: Bovaer, a trade name for a feed additive containing the compound 3-NOP. Bovaer has been shown to reduce enteric methane emissions by thirty to forty percent. The most promising studies have involved Asparogopsis taxiformis (AT), the red seaweed which has been demonstrated to reduce enteric methane emissions by over 80 percent, with one study showing a 98 percent reduction in enteric methane when AT is fed at a high concentration.

While technologies that reduce enteric methane emissions will be vital to reducing the emissions intensity of beef production, the road to development, regulatory approval, production, and distribution throughout the beef supply chain is long and uncertain. Even then, they will not on their own be enough to bring beef-related emissions in line with chicken or pork. Most analyses of on-farm emissions associated with U.S. beef production attribute between forty and sixty percent of emissions to enteric methane production. Dunkley and Dunkley compare estimates of the emissions intensity of beef, pork, and chicken production in the U.S. from studies focusing on the period of 2005 through 2009. They found that the average reported emissions intensity of beef production is 16.25 kg CO₂e/kg, compared to 4.82 for pork and 3.09 for poultry. A good share of this gap is because pigs and chickens produce little to no methane. Even in the best of methane-inhibiting scenarios the emissions intensity of beef production would fall in the range of 6 to 10 kg CO₂e per kg beef—at least twenty-five percent greater than the emissions for pork and double that of chicken. This remaining difference is due to biological factors. such as the relatively long gestational period and high feed conversion ratios of cattle.

Long pregnancies and high feed requirements reflect two types of “maintenance requirements” for beef production. That is, the resources necessary to keep cows and bulls for the purpose of breeding calves each year, and the energy used for temperature maintenance, respiration, and other bodily functions as cattle grow (Figure 3). This concept is often called “dilution of maintenance.”

Figure 3. Cattle Digestive Energy Flows:

Many have raised the question of how much further the emissions intensity of beef production can be reduced through productivity enhancement alone. In her 2011 paper, Capper expressed doubt about whether beef carcass weights can continue to increase. The concern is less biological than mechanical since cattle can and do reach weights well above current norms for slaughter.ather, larger cattle may be challenging and dangerous for ranch hands and current slaughterhouse equipment to handle regularly. A more pragmatic approach is to reduce the impacts of illness and ensure all cattle in shared lots receive proper nutrition to reduce the number of underweight animals that hold averages below targets. Below, I attempt to quantify the emission reduction potential for this and other realistic productivity enhancements to reduce the emissions intensity of beef production.

Is Dilution a Solution? The Beef Productivity Model

The relationship between increasing production efficiency and decreasing emissions intensity is not perfectly straightforward. Faster weight gain in a steer may be achieved by increasing feed quantity, offering more nutritious and calorie-dense feed, or improving health or genetics to convert feed into body weight in a more efficient manner. The same increase in growth rate through any of these mechanisms will impact the emissions intensity of beef production to a different degree. Enteric methane is correlated with feed intake, so a simple increase in consumption would also increase methane production, albeit possibly to a lesser degree. If the increase in feed consumption was not paired with efficiency gains in feed production, then the land use and emissions associated with feed production would also increase in tandem with beef productivity.

To weigh the tradeoffs inherent to these questions, we modeled the relationship between beef cattle populations, beef production, and emissions. The model begins with a population of beef cattle. Beef produced as a byproduct of dairy operations is excluded to avoid additional tradeoffs between beef efficiency and milk productivity. In a baseline model, all variables are set to approximate U.S. averages. We consider seven scenarios in which one or multiple variables, such as calf and cattle mortality, are adjusted to increase cattle productivity (Table 1).

From these inputs, the model calculates a stable cattle population, feed requirements, beef production, and CO₂ equivalent (CO₂e) emissions. Methane (CH₄) and N₂O emissions are converted to CO₂e. Similar to the methods followed by FAOSTAT (Figure 2), this model does not include an estimate of any transportation emissions. Other studies considering transportation of feed and fertilizer and of animals between different production stages have found that transportation accounts for less than one percent of total emissions related to beef production. An additional test added an estimate of the carbon sequestration potential of crop and grazing land if left fallow to the list of emissions sources. The relative impact on emissions intensity did not differ significantly from tests which excluded carbon opportunity cost, as the carbon sequestration potential of land is highly correlated with its suitability for growing feedstuffs. For this reason, we only present results that consider direct emissions at the farm gate. Table 1 describes the seven scenarios considered in this study.

Table 1. Scenarios Considered

Figure 4 presents the impact of each scenario on emissions intensity. An increase in the live calving rate offers modest efficiency gains, causing a 1.7 percent fall in the emissions intensity of beef production, or allowing a commensurate increase in production with constant emissions. Our second scenario, a hypothetical in which 75 percent of calves born are male, may be achievable through sex-sorting of semen before artificial insemination, or through gene editing of bulls. This would allow for enough heifers to replace the number of cows culled each year, but nearly all feedlot cattle would be male. Steers grow faster and have higher carcass weight yields than heifers. As a result, this could reduce the emissions intensity of a pound of beef by 3.3 percent.

Our baseline model uses the most recent calf and cattle mortality values reported by the USDA—6.2 percent of calves and 2.2 percent of cattle were lost prematurely in 2015. The leading cause of death for both were respiratory issues, followed by calving related problems and digestive problems for calves, and old-age and calving related problems for cattle. Together, these causes account for 60.1 and 35.7 percent of calf and cattle deaths, respectively, while fourteen percent of all calf and cattle deaths are recorded as “unknown, non-predator causes.” There is no single solution to meaningfully reducing calf and cattle mortality, however increased investment in animal disease research, veterinary infrastructure, livestock tracking, and better nutrition are all likely to yield results. We find that halving the calf and cattle mortality rate would decrease the emissions intensity of beef by 3.99 percent. Each of these investments would also improve the health and condition of cattle that survive illness or injury, resulting in efficiency benefits that exceed those directly attributable to prevented mortality.

A fourth scenario considers a ten percent improvement in the feed conversion ratio (the ratio of dry matter consumed to weight gained). There are both theoretical and practical limits to improving the feed conversion ratio, however, as suggested by the feed energy losses displayed in figure 3, great gains are possible through several means. These include genetic change to decrease maintenance relative to weight gain, rumen health improvements to reduce energy lost in urine and through methane production, and better nutrient balancing in cattle diets. Our baseline feed conversion rate is founded on herd average values which are often kept down by a small share of cattle that may gain very little weight due to poor health or weak ability to compete in a shared feeding system. Back of the envelope calculations from studies that present the variance in feed use efficiency within a single herd or energy lost to methane-producing bacteria suggest that average feed conversion rates could be improved by between fifteen and forty percent. We use a ten percent improvement in feed conversion rates, consistent with Lamb and Maddock, due to the uncertainty around whether higher estimates are achievable at a national scale.

Possible mechanisms of improvement include vaccines or feed additives that inhibit methane production in the rumen and genetic improvements in the direction of more efficient biological functions. We find that a ten percent increase in feed conversion rate results in an 8.46 percent decrease in the emissions intensity of beef—by far the most impactful single change that we consider.

A combination of these four changes: an increased live calving rate, a population that is 75 percent male, lower calf and cattle mortality, and an improved feed conversion rate, produces an effect on emissions only slightly less than the sum of the parts. The difference owes to overlapping effects on emission sources, but we find this plausible scenario would decrease the emissions intensity of beef production by 16.3 percent or allow American farmers and ranchers to increase beef production by nearly twenty percent without an increase in net emissions.

More modest reductions in emissions intensity could be achieved by increasing the lifespan of breeding cows, which are typically culled between the ages of six and nine. Farmers and ranchers try to keep cows for as many years as possible—the conventional wisdom is that a cow must be bred five or six times to recoup the cost of raising it from birth to breeding age—but there is a tradeoff between cow lifespan and the rate of improvement of herd genetics. Genetic advancements are key mechanisms for the achievement of other productivity gains, so we do not consider pairing this change with other modes of increasing productivity.

Improving growth rates by increasing dry matter intake (DMI) may have some positive effect on productivity. However, our model is not well suited to measure this, as we calculate emissions per unit of feed produced and consumed, and enteric and manure methane emissions are highly correlated with the energy quantity of feed.

The mechanisms for enhancing efficiency discussed above are not exhaustive. A recent pair of studies attempts to quantify the economic and climate benefits of shifting where beef is produced. The pair of papers published in 2023, led by Castonguay, found that shifting some beef production from Southeastern states and the Lower Midwest to the eastern Plains and Upper Midwest could reduce total emissions from beef production by eighteen percent. This is largely achieved through a change in dietary mix as farms in the Upper Midwest feed more grain and crop residue (hulls, stalks, leaves, and other crop byproducts, often in the form of silage) than those in the Southeast.

While our model relies on national averages, and does not have a mechanism for geographic shifts in production, we can calculate a facsimile of the increased feed efficiency considered in the Castonguay papers by increasing the share of cattle on feed. We consider emissions intensity of beef if all beef cattle were weaned directly onto feedlots (or “backgrounded) at six months, leaving only bulls, cows, and calves on pasture (in all other models, forty percent of calves are backgrounded, while sixty percent are “stockers,” calves weaned onto pasture and sent to feedlots at twelve months.) We find this change would decrease emissions intensity by 2.53 percent, less than many previously discussed changes. The difference between our results and those of Castonguay et al. may be partially driven by our decision to assign a share of feed production emissions to crop residues, rather than a carbon neutral byproduct of plants grown for another primary purpose. The lion’s share of the difference is more likely due to the granularity of the model presented in Castonguay et al., which is able to estimate land productivity at a highly localized level. An advantage using national averages, beyond simplicity, is that national productivity enhancement does not assume specific changes in the location of beef producers, which may require cumbersome federal dictates to achieve.

National Policy and International Coordination

Our results demonstrate that a meaningful decline in the emissions intensity of U.S. beef production is achievable through reasonable improvements in beef cattle productivity. Furthermore, the greatest gains may be best achieved by improving animal health, which, counter to a common stereotype of policy solely focused on efficiency improvement, would also have a positive impact on animal welfare. While demand for beef in the United States has not grown dramatically, and stagnated or declined on a per capita basis, global demand for beef continues to rise. As the world’s most efficient major beef producer, the U.S. may be the most sustainable source to fill this demand— producing nearly twenty percent more beef without increasing emissions with multiple efficiency enhancing developments, as described in scenario five.

But productivity improvements are unlikely to occur with stagnant public policy. As we discussed in a recent comment to FDA, there is great potential for improvement in the approval process for livestock intentional genomic alterations. A consistent and approachable approval process is a necessary prerequisite for genetic advancements. such as cattle with improved heat tolerance, or bulls that produce majority male progeny, to have an impact on the efficiency of beef production.

Investment in livestock related research and development should not require deprioritizing other areas of agricultural research. U.S. public investment in research and development has been effectively stagnant for decades despite great economic and environmental returns (Fuglie and Nelson, 2022). The global demand for protein is rising, yet the current land footprint of livestock production—led by cattle occupied land—is enormous. Productivity gains will be vital to avoid the problems associated with overgrazing and conversion of new areas to grazing lands.

Absent veterinary research and disease tracking, threats such as the spread of H5N1 bird flu to dairy cattle in 2024, could pull productivity trends in the opposite direction, increasing the environmental impact of beef production.

While this analysis focuses on the U.S., it is important for these lessons to be applied globally. Many nations have a great deal more to gain by increasing the efficiency of beef production, both through novel means such as introducing heat tolerance into faster growing cattle breeds, and more simple approaches, such as increasing the share of live calves born per cow each year. As an example, in Brazil, only about fifty-one calves are born per hundred cows. If Brazil were to match historic U.S. efficiency improvements, there could be a substantive decrease in land usein and therefore less deforestation. The greatest possible gains in beef production efficiency (or reductions in beef emissions intensity) are more likely if national regulators agree on standards for review, approval, and safe use of novel applications of productivity enhancing technologies.