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As of October 21, 2020 2:26 PM ET

Why are we doing this?


At Burger King, we’ve been working on finding scalable solutions to tackle the climate impact of the food we produce and deliver to guests around the world everyday. To do it right, we started with understanding the facts.

Livestock is responsible for 14.5% of all human-induced greenhouse gas (GHG) emissions, according to estimates from the Food and Agriculture Organization of the United Nations (FAO), and beef production accounts for 41% of those emissions.

Beef Emission

What contributes to beef production’s large footprint?

In our research and discussions with stakeholders globally, we’ve learned that the issues around climate and beef production are complex. There are actually several sources of greenhouse gases (GHGs) along the beef supply chain before it reaches your plate, so when it comes to reducing emissions from the beef supply chain, there are a lot of places where we could step in.

We decided to start with tackling cows’ enteric fermentation and their methane emissions.

What does this mean?

Cows have a complex digestive system consisting of four stomachs, which enables them to eat and digest food that we cannot – such as grass – through a process called enteric fermentation. As the cows digest their feed, they produce a lot of methane. This greenhouse gas is released every time the cows burp and fart the methane gas out. Methane is considered a high contributor to global warming, making it a key area for us to tackle in pursuit of the 2016 Paris Agreement target of limiting global warming to well below 2°C and pursuing efforts to limit it to 1.5°C.

Explore the key sources of GHG emissions
along the beef supply chain below.


"Beef is one of the top commodities that we buy at Burger King. We also know that cattle are one of the top contributors to overall greenhouse gas emissions, so our job is to understand how we can continue to grow our business while still reducing the emissions from cattle over time."

Matt Banton, Head of Innovation and Sustainability, BK

What did
we do to help?


From chamomile tea to baking soda, humans have used natural remedies to help with digestion-related challenges for centuries. So, what if the same natural remedies that help people take care of their stomach aches can help to reduce the impressive amounts of gases cows produce every single day? We teamed up with top level scientists in the US and Mexico to study different herbs, like chamomile, cosmos bipinnatus and lemongrass, in order to find a solution that could potentially benefit the environment and the millions of people that simply love meat.

A new diet for cows that could help them digest better and release less methane.

As a result, we found that by adding 100 grams of dried lemongrass leaves to the cows’ daily feed, we were able to see a reduction of up to 33% on average of methane emissions during the period the diet was fed (the last three-to-four months of the cow’s life in the case of our research). And the good news is that this reduction was powered by a natural plant that grows from Mexico to India.

How was the methane-fighting potential of lemongrass discovered?


Teaming with top researchers from the Autonomous University of the State of Mexico and U.C. Davis, we’ve conducted several rounds of research developing and refining a new cattle menu. The results? Based on this initial research, we’ve discovered that feeding cows with relatively small amounts of lemongrass, during the three-to-four month ‘fattening’ stages of production, reduces their methane emissions by up to 33% on average. Adding 100 grams of dried lemongrass leaves to the cows’ daily diet makes a significant difference.

Click on any of the buttons below to learn more about each stage
in the research journey so far:

We continue to partner with higher education institutions and industry scientists to conduct additional research on this topic and will periodically report on our findings.



"RBI’s Sustainability strategy is grounded in one simple principle - doing what's right. And this project is a really good example; it's a scalable solution to help reduce methane emissions."

Jose Cil, CEO, RBI

How can we work together?


We know our own supply chain is just a small piece of the overall puzzle and we can't do this on our own. It is only when these solutions are widely adopted by the beef industry that we can make a tangible positive impact.

That’s why we are making the Cows Menu formula open source and free for all to use.
We teamed up with scientists to create a formula, making it and our supporting research publicly available so that every fast food brand, meat supplier, and farmer can replicate, test and refine it. If we all work together as an industry to develop and adopt open source solutions such as the Cows Menu formula, we can aim to tangibly reduce methane emissions and develop concrete actions on climate change that aspire to the United Nations Sustainable Development Goals for 2030.

This is all part of our beef sustainability strategy. We’re improving our beef sourcing approach, promoting best practices at all levels of the supply chain, and driving creative solutions through research and collaboration.

We’ve made the formula and supporting research publicly available so that every fast food brand, meat supplier, and farmer can use it. By working together and getting the whole industry to adopt the open source formula, we can potentially reduce methane emissions.


"I would invite the industry, including our competitors, to consider experimenting with what we've done. You’ll be surprised by the results and maybe if we all push together, we can create a much bigger impact than one would imagine."

Fernando Machado, Global CMO, RBI

How to implement
the formula?


Burger King recognizes that global beef production and consumption have considerable climate impact. But we equally know that farmers and ranchers around the world care deeply for their land and their animals. As a large global buyer of beef, we want to support our value chain partners in implementing more potentially ‘climate friendly’ agricultural practices while understanding that they are limited in resources and capacity, and are balancing day-to-day business and sustainability challenges.

We’re excited to introduce industry partners and peers to the Cows’ Menu initiative, which has the potential to reduce the beef industry’s climate impact. After a year of trials and research with scientists at the Autonomous University of the State of Mexico and U.C. Davis, we were able to find a formula for cows’ daily feed made with lemongrass leaves, which suggests a reduction of methane emissions by up to 33% on average during the cow’s last 3 to 4 months of life. The formula is an all-natural supplement to the daily feed ranchers are already using – which based on the research to date, has the potential to be a tangible and achievable solution.

The following “How to” guide takes you step-by-step through the open source formula and the FAQs include all the details to implement the Cows’ Menu initiative in your farming practices and supply chain.

The more ranchers who use it, the more we can learn about the potential of this solution. As we refine, gather learnings and scale the Cows’ Menu initiative we hope to make a tangible difference in helping to mitigate climate change.

Step 1: Sourcing the Lemongrass

The main ingredient for our supplement is lemongrass leaves (Cymbopogon citratus). In cattle, lemongrass has been shown to manipulate the digestion process and improve nutrient utilization, thereby reducing methane formation. Specifically, lemongrass contains bioactive compounds with antimicrobial and antiprotozoal properties which can be used to modify rumen fermentation. (Gagan-Shah et al. 2016, Kumar-Singh et al. 2018, and M. Joch et al. 2016) In our research, the lemongrass supplement was shown to reduce methane emissions by up to 33% on average in the last three to four months of the cow’s life. When sourcing the lemongrass, ranchers must ensure they are sourcing the leaves, which have these nutrients and plant properties we’re looking for – not the stems.

The type of lemongrass used is important! We tested two types of lemongrass (Cymbopogon citratus and Cymbopogon martini) and learned that the chemical composition and polyphenols content of Cymbopogon citratus is better suited to achieve methane reductions. The Cymbopogon citratus should be harvested at the time when ether extract content (essential oils concentration) and total polyphenols content are the highest.

This type of lemongrass grows year-round in tropical, subtropical, and Mediterranean climates worldwide. It's been proven that this plant has beneficial effects like antiseptic, anti-fever, anti-dyspeptic, antioxidant, antinociceptive, carminative, and anti-inflammatory.

Sourcing Lemongrass Sustainably
We know that other feed commodities such as soy and corn are linked with sustainability challenges such as deforestation, pesticide pollution and others. The area of lemongrass under cultivation is currently smaller than would be needed to become a reliable feed for a portion of the beef industry, meaning its growth on a commercial scale needs to be greatly increased. Burger King wants to ensure that we are sourcing lemongrass and expanding its commercial production sustainably. Thus, we will make sustainability a key aspect of our conversations with lemongrass suppliers. We ask those who will also experiment with the Cows Menu formula to do the same and share their learnings.

Step 2: Drying the Lemongrass

Fresh lemongrass leaves need to be dried to facilitate processing. Ideal conditions for the drying process are as follows:

  • Time to Dry: 3-4 weeks
  • Light: Drying must occur away from direct sunlight – preferably indoors – to prevent denaturalization of the bioactive compounds that may be responsible for the reduction of methane formation.
  • Temperature: 18-20 oC (64.4-68 oF) – Temperatures above 40 oC (104 oF) are particularly harmful to the bioactive compounds and should be avoided.
  • Humidity Levels: Low; Under 45%
  • Ventilation: Plants should be stored in a well-ventilated area, spread on fine metal mesh racks placed away from the floor
  • Maintenance: Plants should be rotated once or twice per week to prevent mold or fungus formation

(Luna-Solano et al. (2019)
The goal is to reach a dry matter content of 90%, at which point the leaves will have lost their green color and turned a yellowish brown. We recommend measuring this with a sample of the lemongrass in an air forced drying oven.

During our Mexico research, the lemongrass was dried for 8 weeks at 22 degrees Celsius and 25% humidity.

Step 3: Chopping the Lemongrass

Once dried, the lemongrass needs to be chopped. Chopping the lemongrass is key to facilitate mixing into the cattle feed. Some cows do not like the taste of lemongrass, but once mixed with the feed the cows eat it along with their normal feed.

We recommend using a hammermill to chop or mill the lemongrass to 0.5-1.0 cm size. In this form, the lemongrass can be stored away from moisture in air-sealed containers for several months. No refrigeration is needed.

Step 4: Mix and Feed

The dried and chopped lemongrass is added as a supplement. This means that it is additive to cattle’s current daily intake – not in place of anything. In our research we fed the supplement during the last three to four months of the cows’ lives.

We fed a diet composed of 80.6% concentrate and 19.4% forage with the following ingredients, though ranchers can continue to use their existing daily feed if preferred.

  • 68% steam-flaked corn
  • 9.7% alfalfa
  • 9.7% oat hay
  • 5.7% soybean meal
  • 4.9% molasses
  • 1.9% protected fat

On top of that daily feed, ranchers will add a supplement of 100 grams of lemongrass dry matter per cow per day.

Mixing is imperative to ensure the animals eat all of the lemongrass supplement. To disguise the flavor of the lemongrass, it needs to be thoroughly mixed with the rest of the feedstuffs of the diet to form a total mixed ratio (TMR). TMR is a method of feeding cows that combines feeds formulated to a specific nutrient content into a single feed mix.

Since implementing this type of feed additive is well-suited for controlled feeding, Burger King tested Cows Menu in fed animals. Ideally, feeding the supplement during the whole life of the animal would reduce the overall amount of methane emitted, which is a continuous process over their lifetime. Our supply chain partners will test the feeding of lemongrass over longer periods and Burger King will report on outcomes of these pilots periodically.

Benefits and Changes for Farmers and Ranchers

Increasingly, consumers are putting pressure on companies like Burger King to offer sustainable options, and those companies are looking for suppliers who can support them in becoming more sustainable. We also hope that making efforts to reduce the environmental impact of beef production will help improve consumer perceptions of the beef industry overall. Further, in the context of evolving climate regulations, such as those in California who are mandated by law to cut methane emissions by 40% of 2013 levels by 2030, Cows Menu offers a relatively low investment solution.

We recognize that there will be some additional steps ranchers face when introducing lemongrass as a feed additive. We list those below:

  • Identifying lemongrass suppliers who can easily transport or export to ranchers’ locations
  • Buying and storing lemongrass in bulk, given the significant amount of lemongrass in feeds per day
  • Adjusting feed processes to incorporate the lemongrass additive
  • As needed, investing in infrastructure to dry, chop, and store the lemongrass
  • Monitoring any effects of the diet on the cows and meat quality

We understand that implementing this new practice means a change in ranchers’ regular processes. We also recognize that more research is needed on the impact of the lemongrass additive on farm economics and effects on cows. Initial study results show that the lemongrass diet does not cause negative effects on animal performance, as long as the dose remains 100g of lemongrass per 10kg of feed per day. As we expand this formula with more suppliers, we hope to provide robust insight on commercial metrics such as weight gain, feed conversion ratio, days to slaughter, costs, and lemongrass price changes with increased demand. We also intend to share more research to facilitate implementation and inform longer-term viability.

Ultimately, we believe the hurdles to implement Cows Menu are relatively low considering the potential benefits of the outcome: up to 33% reduction on average of methane emissions per cow during the period the supplement was fed (3 – 4 months in our research), which suggests lower-carbon-footprint cattle production, and the ability to respond to consumer interest in more sustainable food options.


For additional information on the
Cows Menu program,
please reference our FAQs.


"After testing the addition of 100 grams of lemongrass we observed a reduction of up to 33% on average in the daily emissions of methane."

Octavio A. Castelán Ortega, Professor, Autonomous University of the State of Mexico

What are
the opportunities
to scale?


We’re optimistic that peers and supply partners will take advantage of the lemongrass supplement formula, in hopes of potentially achieving in the future a significant climate impact together. Our partners at the Autonomous University of the State of Mexico and U.C. Davis helped us develop a FAQs page, and other resources to guide those efforts. Our next step is to expand the program in our own supply chain as widely as possible, while continuing to study the potential of lemongrass, long-term impact (if any) on cows, and other potential variations to the Cows’ Menu initiative.

We know that it will take time and collaboration to make the Cows’ Menu program a mainstream reality and we are encouraged by the initial feedback.

Partnering to expand the Cows’ Menu in our supply chain:

We are currently embarking on partnerships with supply partners – in Ireland, Austria, Mexico and Brazil – to expand the Cows’ Menu initiative into their operations and further test the commercial viability of a lemongrass supplement. With these next pilots, we will test the formula over a longer period of time and on bigger cattle herds. We will build data in important areas such as animal performance, emissions over time, and economic impacts for farmers, while keeping a close eye on animal welfare.

locations map
Kepak (Ireland)

We are partnering with Kepak in Ireland to test the commercial implications of the Cows Menu program in the supply chain. Feeding the lemongrass over a longer period will provide us with important learnings for farmers and ranchers on emissions, as well as animal weight gain and health.

Marcher Fleischwerke (Austria)

Our collaboration with Marcher Fleischwerke and the University of Vienna aims to validate the findings from our Mexico research. Focused on methane emissions, the pilot will involve replicating the Mexico research - measuring emissions using respiration chambers in a lab – plus a secondary test measuring on a local farm.

GUSI (Mexico)

We are collaborating with GUSI in Mexico to validate the findings from the research conducted at the Autonomous University of the State of Mexico and test the commercial implications of the Cows Menu program in the supply chain.

JBS (Brazil)

We are partnering with JBS in Brazil only to test the commercial implications of the Cows Menu program in the supply chain. Feeding the lemongrass over a longer period will provide us with important learnings for farmers and ranchers on emissions, as well as animal weight gain and health.

Expanding the use of the Cows Menu formula will require a whole lot more lemongrass, so we are supporting our supply chain partners by identifying lemongrass suppliers who can grow with us. Our research suggests that Cymbopogon citratus is better suited to optimize the reduction in methane and so we have developed a specification of this type of lemongrass with the suppliers that we are in discussions with. We recognize that increased demand for other crops has brought sustainability challenges, so sustainable production is a key part of the conversation with lemongrass suppliers.

What does
this mean
for my burger?



Adding lemongrass to the cows’ diet has shown no impact on the taste or texture of the meat in our Whopper. We continue to deliver on our delicious flame grilled flavor that our guests have come to know and love.

The Reduced Methane Emissions Beef – coming from cattle fed the lemongrass supplemented diet - will be available in select restaurants in July 2020. This beef patty will be used for the Whopper and all large burgers currently served at select restaurants in Miami, New York, Austin, Los Angeles and Portland. These burgers will be labeled “REDUCED METHANE EMISSIONS BEEF”, during the promotion period. Beyond launch, we will continue to partner with educational institutions and industry scientists to conduct additional research on this topic. We are also working with suppliers across the globe to expand the program in our supply chain over the coming months. We intend to report out the findings of these pilot partnerships periodically, and will continue to keep stakeholders updated on progress through our parent company, Restaurant Brands International.

Wait, what about the Impossible™ and Rebel Whoppers?
We are providing guests with more options on climate friendly food in our restaurants. As delicious as the classics, both the Impossible™ and Rebel Whopper patties are made from plant-based ingredients. These options are widely available, with our Impossible™ Whopper in US restaurants, and our Rebel Whopper served in the UK, Brazil, Australia and throughout continental Europe. Though Burger King has not calculated the footprint of our plant-based burgers, our partners at Impossible™ Foods have calculated that compared to a beef burger, their burgers use 96% less land and generate 89% fewer GHG emissions.

The plant-based Whopper patties and the new Cows Menu-fed beef at Burger King are two great ways you can continue to enjoy your favorite burger while knowing Burger King is working hard to balance that great taste with potentially lower future climate impacts.


"We're in the business of selling burgers, so we wanted to make a positive impact on climate change without impacting the flame-grill flavor that our guests already know and love."


What's next?


The initial achievements of the Cows Menu program is progress we're proud of. With our partners we have targeted a significant emission source and found that lemongrass could potentially reduce the climate impact of beef production in the future. However, we recognize that nearly all solutions have challenges.

Increasing lemongrass production could bring its own sustainability challenges.

Lemongrass is not currently grown at the scale necessary to support the global beef industry. It's nearly impossible to know the consequences of producing lemongrass on a larger scale, and possibly in new regions. Spikes in demand and over-working the land in other agricultural commodities has led to undesirable consequences. One of the appeals of lemongrass is that it can grow on lower quality land, which could be key in growing its production sustainably.

To address the many questions around scaling lemongrass production, we are engaging stakeholders to help us better understand the potential challenges of large-scale lemongrass production.

Lemongrass will not always grow close to beef production, though identifying the active ingredient in lemongrass would support more efficient delivery to beef producers

Lemongrass is currently grown in tropical, subtropical and Mediterranean regions, which don’t support all significant beef producing regions. We are initially sourcing lemongrass from California and Mexico. We have not established the overall environmental footprint of lemongrass production and distribution to producers, however, based on existing knowledge about what drives emissions in the beef supply chain, we anticipate that the potential emissions savings in the pre-slaughtering phase will be much greater than any additional increases from using lemongrass. The convenience, cost, and potential environmental impacts of lemongrass production being close to cattle production is ideal. In cases where it is not, alternatives may be considered. Additional research to pinpoint the active ‘methane-fighting’ characteristic in lemongrass and to identify other ingredients with this characteristic is a way to expand the Cows Menu program by region.

Cows might get “bored” with lemongrass, so we are testing make sure lemongrass stays effective over longer feeding periods

We all need a little variety in our diet; we can get bored! While the research on lemongrass-fed cows to date has been strong, some longer-term feed additive studies show that cows’ stomachs can adjust over time and limit the initial methane benefits.

Feeding the lemongrass over a longer period of time would help further reduce methane. That’s why, as we expand the Cows Menu program with our supply chain partners, we will test it over longer periods and will validate the research with larger herd sizes.

We must confirm the impacts on farm economics through further pilots within our supply chain

We are excited about the Cows Menu formula because it’s a relatively small change to practices (adding chopped lemongrass to feed) that, based on the research conducted to date, can potentially have a significant climate benefit. Finding win-wins with this program – where changes reduce climate impacts while also positively impacting farm economics – would really help to grow its uptake.

Our research to date has not shown significant effects on animal performance (e.g. weight gain). As we partner with more suppliers and industry scientists, we will study metrics that would influence farm economics, such as cost of inputs and animal performance.

Cows Menu addresses just one of the complex environmental issues linked to beef production. We are tackling others and must collaborate as an industry to really deliver impact.

While significant, we recognize that methane from enteric fermentation is just one of several other important issues when it comes to climate and beef production. For example, beef production has been identified as the largest driver of deforestation globally, which has a huge climate impact. Through our parent company Restaurant Brands International, we are committed to eliminating deforestation from our supply chain - you can read more about our activities here.

One important climate opportunity is the power to actually restore landscapes and store carbon in the soil through the way we raise cattle. In 2020, Burger King, World Wildlife Fund and Cargill are teaming up to accelerate rancher-led sustainability efforts, converting unproductive croplands into native grasslands for cattle grazing, which is known to help reduce greenhouse gas emissions and restore biodiversity. Through this collaboration, nearly 8,000 acres of grassland will be restored through World Wildlife Fund’s existing ranching initiative in the Northern Great Plains.

We recognize that the climate impacts of beef production are vast, and that we need to act now to advance global climate goals. That said, our burgers are derived from cattle (trim). This means that we rely on other larger-cut buyers to partner with us to influence our suppliers toward more sustainable production and distribution practices.

Cows Menu will not solve the climate change problem in the short-term, but it is a scalable solution where we hope to see the impact in our lifetime. We are challenging the industry to improve, and the Cows Menu program is proving that significant improvements are possible by bringing together leading scientific expertise and partnering and sharing lessons along the value chain.

Burger King will continue to pursue innovation and collaboration as we target the 2030 sustainable development agenda and global climate goals. Through the Cows Menu program we invite the feedback, research and participation of the broader beef industry so that together we can meaningfully make a positive climate contribution in the future.

Cows Menu will not solve the climate change problem in the short-term, but it is a scalable solution where we hope to see the impacts in our lifetime. We are challenging the industry to improve, and Cows Menu is proving that significant improvements are possible by bringing together leading scientific expertise and partnering and sharing lessons along the value chain.

Burger King will continue to pursue innovation and collaboration as we target the 2030 sustainable development agenda and global climate goals. Through the Cows Menu program, we invite the feedback, research and participation of the broader beef industry so that together we can meaningfully make a positive climate contribution in the future.