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Thursday, March 28, 2019

Cultured meat

From Wikipedia, the free encyclopedia

Cultured meat is meat produced by in vitro cultivation of animal cells, instead of from slaughtered animals. It is a form of cellular agriculture

Cultured meat is produced using many of the same tissue engineering techniques traditionally used in regenerative medicine. The concept of cultured meat was popularized by Jason Matheny in the early 2000s after co-authoring a seminal paper on cultured meat production and creating New Harvest, the world's first non-profit organization dedicated to supporting in vitro meat research.

In 2013, Mark Post, professor at Maastricht University, was the first to showcase a proof-of-concept for in-vitro lab grown meat by creating the first lab-grown burger patty. Since then, several cultured meat prototypes have gained media attention: however, because of limited dedicated research activities, cultured meat has not yet been commercialized, although Mosa meat plans to bring cultured meat to the market by 2021. In addition, it has yet to be seen whether consumers will accept cultured meat as meat.

The production process still has much room for improvement, but it has advanced in most recent years, leading up to 2018, under various companies. Its applications lead it to have several prospective health, environmental, cultural, and economic considerations in comparison to conventional meat.

Nomenclature

Besides cultured meat, the terms in vitro meat, vat-grown, lab-grown meat, cell-based meat, clean meat, and synthetic meat have all been used by various outlets to describe the product. 

Clean meat is an alternative term that is preferred by some journalists, advocates, and organizations that support the technology. According to the Good Food Institute, the name better reflects the production and benefits of the meat and surpassed "cultured" and "in vitro" in media mentions as well as Google searches.

History

20th century

The theoretical possibility of growing meat in an industrial setting has long captured the public imagination. Winston Churchill suggested in 1931: "We shall escape the absurdity of growing a whole chicken in order to eat the breast or wing, by growing these parts separately under a suitable medium."

In vitro cultivation of muscular fibers was performed as early as 1971 by Russell Ross. Indeed, the abstract was
Smooth muscle derived from the inner media and intima of immature guinea pig aorta were grown for up to 8 weeks in cell culture. The cells maintained the morphology of smooth muscle at all phases of their growth in culture. After growing to confluency, they grew in multiple overlapping layers. By week 4 in culture, microfibrils (110 A) appeared within the spaces between the layers of cells. Basement membrane-like material also appeared adjacent to the cells. Analysis of the microfibrils showed that they have an amino acid composition similar to that of the microfibrillar protein of the intact elastic fiber. These investigations coupled with the radioautographic observations of the ability of aortic smooth muscle to synthesize and secrete extracellular proteins demonstrate that this cell is a connective tissue synthetic cell.
The culturing of stem cells from animals has been possible since the 1990s, including the production of small quantities of tissue which could, in principle be cooked and eaten. NASA has been conducting experiments since 2001, producing cultured meat from turkey cells. The first edible sample was produced by the NSR/Touro Applied BioScience Research Consortium in 2002: goldfish cells grown to resemble fish fillets.

In 1998 Jon F. Vein of the United States filed for, and ultimately secured, a patent (US 6,835,390 B1) for the production of tissue engineered meat for human consumption, wherein muscle and fat cells would be grown in an integrated fashion to create food products such as beef, poultry and fish.

Early 21st century

In 2001, dermatologist Wiete Westerhof from the University of Amsterdam, medical doctor Willem van Eelen, and businessman Willem van Kooten announced that they had filed for a worldwide patent on a process to produce cultured meat. In the process, a matrix of collagen is seeded with muscle cells, which are then bathed in a nutritious solution and induced to divide. Scientists in Amsterdam study the culture medium, while the University of Utrecht studies the proliferation of muscle cells, and the Eindhoven University of Technology is researching bioreactors.

In 2003, Oron Catts and Ionat Zurr of the Tissue Culture and Art Project and Harvard Medical School exhibited in Nantes a "steak" a few centimetres wide, grown from frog stem cells, which was cooked and eaten.

The first peer-reviewed journal article published on the subject of laboratory-grown meat appeared in a 2005 issue of Tissue Engineering.

In 2008, PETA offered a $1 million prize to the first company to bring lab-grown chicken meat to consumers by 2012. The Dutch government has put US$4 million into experiments regarding cultured meat. The In Vitro Meat Consortium, a group formed by international researchers interested in the technology, held the first international conference on the production of cultured meat, hosted by the Food Research Institute of Norway in April 2008, to discuss commercial possibilities. Time magazine declared cultured meat production to be one of the 50 breakthrough ideas of 2009. In November 2009, scientists from the Netherlands announced they had managed to grow meat in the laboratory using the cells from a live pig.

As of 2012, 30 laboratories from around the world have announced that they are working on cultured meat research.

The first cultured beef burger patty, created by Dr. Mark Post at Maastricht University, was eaten at a demonstration for the press in London in August 2013. It was made from over 20,000 thin strands of muscle tissue. This burger cost Dr. Post over $300,000 to make and over 2 years to produce. Two other companies have also begun to culture meat; Memphis Meats in the US and SuperMeat in Israel.

As of February 2017, a recent report has shown that the price of these cultured burgers has dropped dramatically. Going from roughly over $300,000 to $11.36 in just 3 and a half years. This cost is now only 9-10 times more expensive per pound than standard ground beef.

First public trial

Hanni Rützler tastes the world's first cultured hamburger, 5 August 2013.
 
On August 5, 2013, the world's first lab-grown burger was cooked and eaten at a news conference in London. Scientists from Maastricht University in the Netherlands, led by professor Mark Post, had taken stem cells from a cow and grown them into strips of muscle which they then combined to make a burger. The burger was cooked by chef Richard McGeown of Couch's Great House Restaurant, Polperro, Cornwall, and tasted by critics Hanni Rützler, a food researcher from the Future Food Studio and Josh Schonwald. Rützler stated,
There is really a bite to it, there is quite some flavour with the browning. I know there is no fat in it so I didn't really know how juicy it would be, but there is quite some intense taste; it's close to meat, it's not that juicy, but the consistency is perfect. This is meat to me... It's really something to bite on and I think the look is quite similar.
Rützler added that even in a blind trial she would have taken the product for meat rather than a soya copy.

Tissue for the London demonstration was cultivated in May 2013, using about 20,000 thin strips of cultured muscle tissue. Funding of around €250,000 came from an anonymous donor later revealed to be Sergey Brin. Post remarked that "there's no reason why it can't be cheaper...If we can reduce the global herd a millionfold, then I'm happy".

Further progress from startups

It's just a matter of time before this is gonna happen, I'm absolutely convinced of that. In our case, I estimate the time to be about 3 years before we are ready to enter the market on a small scale, about 5 years to enter the market on a larger scale, and if you'd ask me: "When will [cultured meat] be in the supermarket around the corner?" That'll be closer to 10 than to 5 years, I think. – Peter Verstrate, Mosa Meat (2018)
Since the first public trial, several startups have made advances in the field. Mosa Meat co-founded by Mark Post continuous research with a focus on cultured beef. The company was able to significantly lower the costs of production.

Memphis Meats, a Silicon Valley startup founded by a cardiologist, launched a video in February 2016 showcasing its cultured beef meatball. In March 2017, it showcased chicken tenders and duck a l'orange, the first cultured poultry-based foods shown to the public.

An Israeli company, SuperMeat, ran a viral crowdfunding campaign in 2016 for its work on cultured chicken.

Finless Foods, a San Francisco-based company aimed at cultured fish, was founded in June 2016. In March 2017 it commenced laboratory operations and progressed quickly. Director Mike Selden said in July 2017 to expect bringing cultured fish products on the market within two years (by the end of 2019).

In March 2018, JUST, Inc. (in 2011 founded as Hampton Creek in San Francisco) claimed to be able to present a consumer product from cultured meat by the end of 2018. According to CEO Josh Tetrick the technology is already there, and now it is merely a matter of applying it. JUST has about 130 employees and a research department of 55 scientists, where lab meat from poultry, pork and beef is being developed. They would have already solved the problem of feeding the stem cells with only plant resources. JUST receives sponsoring from Chinese billionaire Li Ka-shing, Yahoo! co-founder Jerry Yang and according to Tetrick also from Heineken International amongst others.

The Dutch startup Meatable, consisting of Krijn de Nood, Daan Luining, Ruud Out, Roger Pederson, Mark Kotter and Gordana Apic among others, reported in September 2018 it had succeeded in growing meat using pluripotent stem cells from animals' umbilical cords. Although such cells are reportedly difficult to work with, Meatable claimed to be able to direct them to behave using their proprietary technique in order to become muscle cells or fat cells as needed. The major advantage is that this technique bypasses fetal bovine serum, meaning that no animal has to be killed in order to produce meat. That month, it was estimated there were about 30 cultured meat startups across the world. A Dutch House of Representatives Commission meeting discussed the importance and necessity of governmental support for researching, developing and introducing cultured meat in society, speaking to representatives of three universities, three startups and four civil interest groups on 26 September 2018.

Production

There are three stages in the production of cultured meat: selection of starter cells, treatment of growth medium, and scaffolding.

Starter cells

Myoblasts are one precursor to muscle cells, and their fibers are shown in yellow and nuclei shown in blue.
 
The initial stage of growing cultured meat is to collect cells that have a rapid rate of proliferation (high cell reproduction rate). Such cells include embryonic stem cells, adult stem cells, myosatellite cells, or myoblasts. Stem cells proliferate the quickest, but have not yet begun development towards a specific kind of cell, which creates the challenge of splitting the cells and directing them to grow a certain way. Fully developed muscle cells are ideal in the aspect that they have already finished development as a muscle, but proliferate hardly at all. Therefore, cells such as myosattelite and myoblast cells are often used as they still proliferate at an acceptable rate, but also sufficiently differentiate from other types of cells.

Growth medium

The cells are then treated by applying a protein that promotes tissue growth, which is known as a growth medium. These mediums should contain the necessary nutrients and appropriate quantity of growth factors. They are then placed in a culture medium, in a bio-reactor, which is able to supply the cells with the energetic requirements they need.

Scaffold

Muscle tissue is developed from the growth medium and organized in a three-dimensional structure by the scaffold for end product.

To culture three-dimensional meat, the cells are grown on a scaffold, which is a component that directs its structure and order. The ideal scaffold is edible so the meat does not have to be removed, and periodically moves to stretch the developing muscle, thereby simulating the animal body during normal development. Additionally the scaffold must maintain flexibility in order to not detach from the developing myotubes (early muscle fibers). Scaffold must also allow vascularization (creation of blood vessels) in order for normal development of muscle tissue.

Other considerations

Scaffold-based production techniques can only be appropriately used in boneless or ground meats (processed). The end result of this process would be meats such as hamburgers or sausages. In order to create more structured meats, for example steak, muscle tissue must be structured in directed and self-organized means or by proliferation of muscle tissue already existing. Additionally, the presence of gravitational, magnetic, fluid flow, and mechanical fields have an effect on the proliferation rates of the muscle cells. Processes of tension such as stretching and relaxing increased differentiation into muscle cells.

The first cultured hamburger, ready to be fried on 5 August 2013.
 
Once this process has been started, it would be theoretically possible to continue producing meat indefinitely without introducing new cells from a living organism. It has been claimed that, conditions being ideal, two months of cultured meat production could deliver up to 50,000 tons of meat from ten pork muscle cells.

Cultured meat production requires a preservative, such as sodium benzoate, to protect the growing meat from yeast and fungus. Collagen powder, xanthan gum, mannitol and cochineal could be used in different ways during the process.

The price of cultured meat at retail outlets like grocery stores and supermarkets may decrease to levels that middle-class consumers consider to be "inexpensive" due to technological advancements.

Research challenges

The science for cultured meat is an outgrowth of the field of biotechnology known as tissue engineering. The technology is simultaneously being developed along with other uses for tissue engineering such as helping those with muscular dystrophy and, similarly, growing transplant organs. There are several obstacles to overcome if it has any chance of succeeding; at the moment, the most notable ones are scale and cost.
  • Proliferation of muscle cells: Although it is not very difficult to make stem cells divide, for meat production it is necessary that they divide at a quick pace, producing the solid meat. This requirement has some overlap with the medical branch of tissue engineering.
  • Culture medium: Proliferating cells need a food source to grow and develop. The growth medium should be a well-balanced mixture of ingredients and growth factors. Scientists have already identified possible growth media for turkey, fish, sheep and pig muscle cells. Depending on the motives of the researchers, the growth medium has additional requirements.
    • Commercial: The growth medium should be inexpensive to produce. A plant-based medium may be less expensive than fetal bovine serum.
    • Animal welfare: The growth medium should be devoid of animal sources (except for the initial "mining" of the original stem cells).
    • Non-Allergenic: While plant-based growth media are "more realistic," will be cheaper, and will reduce the possibility of infectious agents, there is also the possibility that plant-based growth media may cause allergic reactions in some consumers.
  • Bioreactors: Nutrients and oxygen need to be delivered close to each growing cell, on the scale of millimeters. In animals this job is handled by blood vessels. A bioreactor should emulate this function in an efficient manner. The usual approach is to create a sponge-like matrix in which the cells can grow and perfuse it with the growth medium.
Additionally, there is no dedicated scientific research discipline for cellular agriculture and its development. The past research undertaken into cellular agriculture were isolated from each other, and they did not receive significant academic interest. Although it currently exists, long-term strategies are not sufficiently funded for development and severely lack a sufficient amount of researchers.

Differences from conventional meat

The first cultured hamburger being fried on 5 August 2013.

Health

Large-scale production of cultured meat may or may not require artificial growth hormones to be added to the culture for meat production.

Researchers have suggested that omega-3 fatty acids could be added to cultured meat as a health bonus. In a similar way, the omega-3 fatty acid content of conventional meat can also be increased by altering what the animals are fed. An issue of Time magazine has suggested that the cell-cultured process may also decrease exposure of the meat to bacteria and disease.

Due to the strictly controlled and predictable environment, cultured meat production has been compared to vertical farming, and some of its proponents have predicted that it will have similar benefits in terms of reducing exposure to dangerous chemicals like pesticides and fungicides, severe injuries, and wildlife.

Concern in regards to developing antibiotic resistance due to the use of antibiotics in livestock, livestock and livestock-derived meat serving as a major source of disease outbreaks (including bird flu, anthrax, swine flu, and listeriosis), and long-term processed meat consumption being associated with increased heart disease, digestive tract cancer, and type 2 diabetes currently plague livestock-based meat. In regards to cultured meat, strict environmental controls and tissue monitoring can prevent infection of meat cultures from the outset, and any potential infection can be detected before shipment to consumers.

In addition to the prevention and lack of diseases, and lack of the use of antibiotics or any other chemical substances, cultured meat can also leverage numerous biotechnology advancements, including increased nutrient fortification, individually-customized cellular and molecular compositions, and optimal nutritional profiles, all making it much healthier than livestock-sourced meat.

Artificiality

Although cultured meat consists of genuine animal muscle cells that are the same as in traditional meat, consumers may find such a high-tech approach to food production distasteful (see appeal to nature). Cultured meat has been disparagingly described as 'Frankenmeat'.

If cultured meat turns out to be different in appearance, taste, smell, texture, or other factors, it may not be commercially competitive with conventionally produced meat. The lack of fat and bone may also be a disadvantage, for these parts make appreciable culinary contributions. However, the lack of bones and/or fat may make many traditional meat preparations, such as buffalo wings, more palatable to small children.

Environmental

Research has suggested that environmental impacts of cultured meat would be significantly lower than normally slaughtered beef. For every hectare that is used for vertical farming and/or cultured meat manufacturing, anywhere between 10 and 20 hectares of land may be converted from conventional agriculture usage back into its natural state. Vertical farms (in addition to cultured meat facilities) could exploit methane digesters to generate a small portion of its own electrical needs. Methane digesters could be built on site to transform the organic waste generated at the facility into biogas which is generally composed of 65% methane along with other gasses. This biogas could then be burned to generate electricity for the greenhouse or a series of bioreactors.

A study by researchers at Oxford and the University of Amsterdam found that cultured meat was "potentially ... much more efficient and environmentally-friendly", generating only 4% greenhouse gas emissions, reducing the energy needs of meat generation by up to 45%, and requiring only 2% of the land that the global meat/livestock industry does. The patent holder Willem van Eelen, the journalist Brendan I. Koerner, and Hanna Tuomisto, a PhD student from Oxford University all believe it has less environmental impact. This is in contrast to cattle farming, "responsible for 18% of greenhouse gases" and causing more damage to the environment than the combined effects of the world's transportation system. Vertical farming may completely eliminate the need to create extra farmland in rural areas along with cultured meat. Their combined role may create a sustainable solution for a cleaner environment.

One skeptic is Margaret Mellon of the Union of Concerned Scientists, who speculates that the energy and fossil fuel requirements of large-scale cultured meat production may be more environmentally destructive than producing food off the land. However, S.L. Davis has speculated that both vertical farming in urban areas and the activity of cultured meat facilities may cause relatively little harm to the species of wildlife that live around the facilities. Dickson Despommier speculated that natural resources may be spared from depletion due to vertical farming and cultured meat, making them ideal technologies for an overpopulated world. Conventional farming, on the other hand, kills ten wildlife animals per hectare each year. Converting 4 hectares (10 acres) of farmland from its man-made condition back into either pristine wilderness or grasslands would save approximately 40 animals while converting 1 hectare (2 acres) of that same farmland back into the state it was in prior to settlement by human beings would save approximately 80 animals. 

Additionally, the cattle industry uses a large amount of water for producing animal feed, animal rearing, and for sanitation purposes. It is estimated that the water recycled from livestock manure is contributing "33% of global nitrogen and phosphorus pollution," "50% of antibiotic pollution," "37% of toxic heavy metals," and "37% of pesticides" which contaminate the planet's freshwater.

The role of genetic modification

Techniques of genetic engineering, such as insertion, deletion, silencing, activation, or mutation of a gene, are not required to produce cultured meat. Furthermore, cultured meat is composed of a tissue or collection of tissues, not an organism. Therefore, it is not a genetically modified organism (GMO). Since cultured meats are simply cells grown in a controlled, artificial environment, some have commented that cultured meat more closely resembles hydroponic vegetables, rather than GMO vegetables.

More research is being done on cultured meat, and although the production of cultured meat does not require techniques of genetic engineering, there is discussion among researchers about utilizing such techniques to improve the quality and sustainability of cultured meat. Fortifying cultured meat with nutrients such as beneficial fatty acids is one improvement that can be facilitated through genetic modification. The same improvement can be made without genetic modification, by manipulating the conditions of the culture medium. Genetic modification may also play a role in the proliferation of muscle cells. The introduction of myogenic regulatory factors, growth factors, or other gene products into muscle cells may increase production past the capacity of conventional meat.

To avoid the use of any animal products, the use of photosynthetic algae and cyanobacteria has been proposed to produce the main ingredients for the culture media, as opposed to the very commonly used fetal bovine or horse serum. Some researchers suggest that the ability of algae and cyanobacteria to produce ingredients for culture media can be improved with certain technologies, most likely not excluding genetic engineering.

Ethical considerations

The Australian bioethicist Julian Savulescu said "Artificial meat stops cruelty to animals, is better for the environment, could be safer and more efficient, and even healthier. We have a moral obligation to support this kind of research. It gets the ethical two thumbs up." Animal welfare groups are generally in favor of the production of cultured meat because it does not have a nervous system and therefore cannot feel pain. Reactions of vegetarians to cultured meat vary: some feel the cultured meat presented to the public in August 2013 was not vegetarian as fetal calf serum was used in the growth medium. However, since then lab grown meat has been grown under a medium that doesn't involve fetal serum. American philosopher Carlo Alvaro argues that the question of the morality of eating in vitro meat has been discussed only in terms of convenience. Alvaro proposes a virtue-oriented approach that may reveal aspects of the issue not yet explored, such as the suggestion that the obstinacy of wanting to produce lab-grown meat stems from unvirtuous motives, i.e., "lack of temperance and misunderstanding of the role of food in human flourishing."

Independent inquiries may be set up by certain governments to create a degree of standards for cultured meat. Laws and regulations on the proper creation of cultured meat products would have to be modernized to adapt to this newer food product. Some societies may decide to block the creation of cultured meat for the "good of the people" – making its legality in certain countries a questionable matter.

Cultured meat needs technically sophisticated production methods making it harder for communities to produce food self-sufficiently and potentially increasing dependence on global food corporations.

Requirement for additional regulation

Independent inquiries may be set up by certain governments to create a degree of standards for cultured meat. Once cultured meat becomes more cost-efficient, it is necessary to decide who will regulate the safety and standardization of these products. Prior to being available for sale, the European Union and Canada will require approved novel food applications. Additionally, the European Union requires that cultured animal products and production must prove safety, by an approved company application, which became effective as of January 1, 2018. Within the United States, there is discussion of whether or not cultured meat regulation will be handled by the FDA (Food and Drug Administration) or the USDA (United States Department of Agriculture). The main point of content is whether or not cultured meat is labeled as "food" and regulated by the FDA or as a "meat food product" and regulated by the USDA. Under the FDA, cultured meat would need to follow the FFDCA and have a Food Safety Plan (FSP). Under the USDA, cultured meat would need be regulated by the FSIS who must deem the ingredients safe and usable. It could also be regulated by both government organizations.

Religious considerations

Jewish rabbinical authorities disagree whether cultured meat is kosher (food that may be consumed, according to Jewish dietary laws). However, all rabbis agree that if the original cells were taken from a slaughtered kosher animal then the cultured meat will be kosher. Some even think that it would be kosher even if coming from non-kosher animals like pigs, as well as from live animals, however some disagree. Some Muslim scholars have stated that cultured meat would be allowed by Islamic law if the original cells and growth medium were halal. Within Hindu culture, there is significant importance of cattle in religion where the majority of Hindus reject consumption of a cow's meat. The potential of a "meatless beef" has driven debate among Hindus on the acceptance of eating it. A significant number of Hindus reject the meat due to the high prevalence of a vegetarian diet.

Economic

The production of cultured meat is currently very expensive – in 2008 it was about US$1 million for a piece of beef weighing 250 grams (0.55 lb) – and it would take considerable investment to switch to large-scale production. However, the In Vitro Meat Consortium has estimated that with improvements to current technology there could be considerable reductions in the cost of cultured meat. They estimate that it could be produced for €3500/tonne (US$5424/tonne in March 2008), which is about twice the cost of unsubsidized conventional European chicken production.

In a March 2015 interview with Australia's ABC, Mark Post said that the marginal cost of his team's original €250,000 burger was now €8.00. He estimates that technological advancements would allow the product to be cost-competitive to traditionally sourced beef in approximately ten years. In 2016, the cost of production of cultured beef for food technology company Memphis Meats was $18,000 per pound ($40,000/kg). As of June 2017 Memphis Meats reduced the cost of production to below $2,400 per pound ($5,280/kg).

In fiction

Cultured meat has often featured in science fiction. The earliest mention may be in Two Planets (1897) by Kurd Lasswitz, where "synthetic meat" is one of the varieties of synthetic food introduced on Earth by Martians. Other notable books mentioning artificial meat include Ashes, Ashes (1943) by René Barjavel; The Space Merchants (1952) by Frederik Pohl and C.M. Kornbluth; The Restaurant at the End of the Universe (1980) by Douglas Adams; Le Transperceneige (Snowpiercer) (1982) by Jacques Lob and Jean-Marc Rochette; Neuromancer (1984) by William Gibson; Oryx and Crake (2003) by Margaret Atwood; Deadstock (2007) by Jeffrey Thomas; Accelerando (2005) by Charles Stross; Ware Tetralogy by Rudy Rucker; and Divergent (2011) by Veronica Roth

In film, artificial meat has featured prominently in Giulio Questi's 1968 drama La morte ha fatto l'uovo (Death Laid an Egg) and Claude Zidi's 1976 comedy L'aile ou la cuisse (The Wing or the Thigh). "Man-made" chickens also appear in David Lynch's 1977 surrealist horror, Eraserhead. Most recently, it was also featured prominently as the central theme of the movie Antiviral (2012). 

The Starship Enterprise from the TV and movie franchise Star Trek apparently provides a synthetic meat or cultured meat as a food source for the crew, although crews from The Next Generation and later use replicators

In the ABC sitcom Better Off Ted (2009–2010), the episode "Heroes" features Phil (Jonathan Slavin) and Lem (Malcolm Barrett) trying to grow cowless beef.

In the videogame Project Eden, the player characters investigate a cultured meat company called Real Meat. 

In the movie "GalaxyQuest", during the dinner scene, Tim Allen's character refers to his steak tasting like "real Iowa beef".

In popular culture

Cultured meat was a subject on an episode of the Colbert Report on 17 March 2009.

In February, 2014, a biotech startup called BiteLabs ran a campaign to generate popular support for artisanal salami made with meat cultured from celebrity tissue samples. The campaign became viral on Twitter, where users tweeted at celebrities asking them to donate muscle cells to the project. Media reactions to BiteLabs variously identified the startup as a satire on startup culture, celebrity culture, or as a discussion prompt on bioethical concerns. While BiteLabs claimed to be inspired by the success of Sergey Brin's burger, the company is seen as an example of critical design rather than an actual business venture. 

In late 2016, cultured meat was involved in a case in the episode "How The Sausage Is Made" of CBS show Elementary.

Environmental impact of meat production

From Wikipedia, the free encyclopedia

The environmental impact of meat production varies because of the wide variety of agricultural practices employed around the world. All agricultural practices have been found to have a variety of effects on the environment. Some of the environmental effects that have been associated with meat production are pollution through fossil fuel usage, animal methane, effluent waste, and water and land consumption. Meat is obtained through a variety of methods, including organic farming, free range farming, intensive livestock production, subsistence agriculture, hunting, and fishing.
 
The 2006 report Livestock's Long Shadow, released by the Food and Agriculture Organization (FAO) of the United Nations, states that "the livestock sector is a major stressor on many ecosystems and on the planet as a whole. Globally it is one of the largest sources of greenhouse gases (GHG) and one of the leading causal factors in the loss of biodiversity, while in developed and emerging countries it is perhaps the leading source of water pollution." Removing all US agricultural animals would reduce US greenhouse gas emissions by 2.6%. (In this and much other FAO usage, but not always elsewhere, poultry are included as "livestock".) A 2017 study published in the journal Carbon Balance and Management found animal agriculture's global methane emissions are 11% higher than previous estimates based on data from the Intergovernmental Panel on Climate Change. Some fraction of these effects is assignable to non-meat components of the livestock sector such as the wool, egg and dairy industries, and to the livestock used for tillage. Livestock have been estimated to provide power for tillage of as much as half of the world's cropland. According to production data compiled by the FAO, 74 percent of global livestock product tonnage in 2011 was accounted for by non-meat products such as wool, eggs and milk. Meat is also considered one of the prime factors contributing to the current sixth mass extinction. A July 2018 study in Science asserts that meat consumption will increase as the result of human population growth and rising individual incomes, which will increase carbon emissions and further reduce biodiversity.

In November 2017, 15,364 world scientists signed a Warning to Humanity calling for, among other things, drastically diminishing our per capita consumption of meat.

Impact of animal products, compared to agriculture overall
Categories Contribution of farmed animal product [%]
Calories
18
Proteins
37
Land use
83
Greenhouse gases
58
Water pollution
57
Air pollution
56
Freshwater withdrawals
33

Consumption and production trends

Changes in demand for meat may change the environmental impact of meat production by influencing how much meat is produced. It has been estimated that global meat consumption may double from 2000 to 2050, mostly as a consequence of increasing world population, but also partly because of increased per capita meat consumption (with much of the per capita consumption increase occurring in the developing world). Global production and consumption of poultry meat have recently been growing at more than 5 percent annually. Trends vary among livestock sectors. For example, global per capita consumption of pork has increased recently (almost entirely due to changes in consumption within China), while global per capita consumption of ruminant meats has been declining.

Grazing and land use

Dryland grazing on the Great Plains in Colorado.
 
In comparison with grazing, intensive livestock production requires large quantities of harvested feed, this overproduction of feed can also hold negative effects. The growing of cereals for feed in turn requires substantial areas of land. However, where grain is fed, less feed is required for meat production. This is due not only to the higher concentration of metabolizable energy in grain than in roughages, but also to the higher ratio of net energy of gain to net energy of maintenance where metabolizable energy intake is higher. It takes seven pounds of feed to produce a pound of beef (live weight), compared to more than three pounds for a pound of pork and less than two pounds for a pound of chicken. However, assumptions about feed quality are implicit in such generalizations. For example, production of a pound of beef cattle live weight may require between 4 and 5 pounds of feed high in protein and metabolizable energy content, or more than 20 pounds of feed of much lower quality.

Free-range animal production requires land for grazing, which in some places has led to land use change. According to FAO, "Ranching-induced deforestation is one of the main causes of loss of some unique plant and animal species in the tropical rainforests of Central and South America as well as carbon release in the atmosphere."

Raising animals for human consumption accounts for approximately 40% of the total amount of agricultural output in industrialized countries. Grazing occupies 26% of the earth's ice-free terrestrial surface, and feed crop production uses about one third of all arable land.

Land quality decline is sometimes associated with overgrazing, as these animals are removing much needed nutrients from the soil without the land having time to recover. Rangeland health classification reflects soil and site stability, hydrologic function, and biotic integrity. By the end of 2002, the US Bureau of Land Management (BLM) had evaluated rangeland health on 7,437 grazing allotments (i.e., 35 percent of its grazing allotments or 36 percent of the land area contained in its grazing allotments) and found that 16 percent of these failed to meet rangeland health standards due to existing grazing practices or levels of grazing use. This led the BLM to infer that a similar percentage would be obtained when such evaluations were completed. Soil erosion associated with overgrazing is an important issue in many dry regions of the world. However, on US farmland, much less soil erosion is associated with pastureland used for livestock grazing than with land used for production of crops. Sheet and rill erosion is within estimated soil loss tolerance on 95.1 percent, and wind erosion is within estimated soil loss tolerance on 99.4 percent of US pastureland inventoried by the US Natural Resources Conservation Service.

Environmental effects of grazing can be positive or negative, depending on the quality of management, and grazing can have different effects on different soils and different plant communities. Grazing can sometimes reduce, and other times increase, biodiversity of grassland ecosystems. A study comparing virgin grasslands under some grazed and nongrazed management systems in the US indicated somewhat lower soil organic carbon but higher soil nitrogen content with grazing. In contrast, at the High Plains Grasslands Research Station in Wyoming, the top 30 cm of soil contained more organic carbon as well as more nitrogen on grazed pastures than on grasslands where livestock were excluded. Similarly, on previously eroded soil in the Piedmont region of the US, pasture establishment with well-managed grazing of livestock resulted in high rates of both carbon and nitrogen sequestration relative to results obtained where grass was grown without grazing. Such increases in carbon and nitrogen sequestration can help mitigate greenhouse gas emission effects. In some cases, ecosystem productivity may be increased due to grazing effects on nutrient cycling.

Bovine connection to increasing atmospheric greenhouse gases

Ruminants have a four-compartment stomach that contains microbes. Microbes aid in the digestion of food. Some of these microbes (methanogenic archaea) produce methane as a metabolic byproduct. When the bovine ingests the food, the food travels to the rumen where microbes begin breaking down the roughage. The bovine then belches; this is when methane is first introduced to the atmosphere during this process. The food belched up is also known as cud. The cud is then swallowed where it is digested once more in the rumen before it enters the reticulum, omasum, abomasum, small intestine, and large intestine respectively. The remains exit where approximately 5% of the methane produced from cattle is emitted. This process is known as enteric fermentation. Enteric Fermentation occurs when methane is produced as cows' rumens digest carbohydrates through microbial fermentation.

Methane makes up approximately 27% of rumen gases, carbon dioxide makes up approximately 66% of rumen gases, nitrogen makes up approximately 7% of rumen gases, and oxygen and hydrogen make up the remaining percentages. Animal waste contributes to 5% of methane sources available in the atmosphere while enteric fermentation makes up to 16% of all methane sources currently in the atmosphere. Together, that makes up 21% of the methane released into the atmosphere. Compare this percentage to the methane contribution of natural wetlands, which make up 22% of the methane released in the atmosphere.

More methane is produced from cows' belching than from flatulence; approximately 95% of methane produced by bovines is from belching. Methane is 84 times more potent than carbon dioxide and speeds up the Greenhouse Effect. The Greenhouse Effect is a process that warms Earth's surface and keeps the global temperature stable at 33 °C by retaining a portion of greenhouse gases on Earth while releasing the rest back into space. As more methane and other greenhouse gases are introduced and held in the atmosphere or on Earth's surface, the global temperature will rise due to the fact that greenhouse gases absorb infrared radiation, also known as heat. The methane concentration has been growing exponentially since 1984 and is projected to continue to do so.

Any deviation from the global temperature of 33 °C will result in drastic effects in climate change such as a loss of biodiversity and more intense and unpredictable weather patterns. Coastal erosion is also another effect of climate change which leads to loss of fertile land as the sea levels rise. The sporadic weather patterns and change in seasons will also lead to unpredictable farming patterns. Pests and vector borne diseases will become more common and available as the global temperature rises. Growing seasons will become longer in cooler areas. 

Americans are one of the largest contributing groups to the excessive amounts of beef consumption worldwide. The United States is the fourth largest consumer of beef and the 16th largest consumer of dairy worldwide. Americans consume four times the world average of beef consumption. On average, each American consumes around 600 pounds of beef and cow dairy products annually. The average American eats about 50 pounds of beef annually. 

There are some controllable ways to reduce the amount of methane released into the atmosphere. Improving the digestion of bovine will decrease the bovine's tendency to belch and release digestive gases through the anus, which emit methane into the atmosphere. One way is to grind the cattle feed to make it finer which leads the cow to take less time and energy to digest it, and as a result, less methane is produced in the process. Scientists have introduced garlic into cattle's diets; garlic inhibits the microorganisms in the intestines from producing methane. Researchers at Penn State introduced 3-nitrooxypropanol to the cows' diets which suppresses the cows' ability to release methane but leads the cattle to gain weight since they are using less energy to digest their food. Studies have been conducted in adding plants high in tannin to ruminants' diets which in turn effectively reduces their methane emissions. All potential solutions in reducing bovine's methane emissions have proved to not be cost efficient which inhibits current farmers and ranchers from adopting them.

Another way to reduce methane released in the atmosphere is to monitor dietary practices. If the demand for cattle decreases, then the supply of cattle will also decrease as a result. Reducing beef and dairy intake in one's diet decreases one's risk in developing diseases such as lung cancer, breast cancer, ovarian cancer, prostate cancer, diabetes, Alzheimers, and heart disease. Dairy contains high levels of saturated fats. For example, cheese is 70% saturated fat. Overall, the overconsumption of beef and dairy shortens one's lifespan. Chicken, seafood, quinoa, tofu, mushrooms, lentils, nuts, and many other protein-rich foods are healthier alternative to beef. Alternatives that contain less saturated fats than cow milk include: almond milk, coconut milk, soy milk, rice milk, and hemp milk. Being environmentally conscious when making dietary decisions as well as altering the cow's feed will effectively decrease bovine's methane emissions into the atmosphere.

Resources

Estimated virtual water requirements
for various crops (m³ water/ton)

Hoekstra
& Hung
(2003)
Chapagain
& Hoekstra
(2003)
Zimmer
& Renault
(2003)
Oki
et al.
(2003)
Average
Beef
15,977 13,500 20,700 16,730
Pork
5,906 4,600 5,900 5,470
Cheese
5,288

5,290
Poultry
2,828 4,100 4,500 3,810
Eggs
4,657 2,700 3,200 3,520
Rice 2,656
1,400 3,600 2,550
Soybeans 2,300
2,750 2,500 2,520
Wheat 1,150
1,160 2,000 1,440
Maize 450
710 1,900 1,020
Milk
865 7,90 560 740
Potatoes 160
105
130

Virtual water use for livestock production includes water used in producing feed. However, virtual water use data, such as those shown in the table, are often unrelated to environmental impacts of water use. For example, in a high-rainfall area, if similar soil infiltration capacity is maintained across different land uses, mm of groundwater recharge and hence sustainability of water use tends to be about the same for food crop production, meat-yielding livestock production, and saddle horse production, although virtual water use per kg of food produced may be several hundred L, several thousand L, and an infinite number of L, respectively. In contrast, in some low-rainfall areas, some livestock production is more sustainable than food crop production, from a water use standpoint, despite higher virtual water use per kg of food produced. Unirrigated land in many water-short areas may support grassland ecosystems in perpetuity, and thus may be able to support well-managed production of grazing cattle or sheep with a sustainable level of water use, whereas more water-demanding food crops would be unsustainable in the long run due to inadequate surface water supplies and groundwater recharge to sustain a high level of irrigation. Such considerations are important on much rangeland in western North America and elsewhere that can support cow-calf operations, backgrounding of stocker cattle, and sheep flocks. In the US, withdrawn surface water and groundwater use for crop irrigation exceeds that for livestock by about a ratio of 60:1.

Also, the high virtual water use figures associated with meat production do not necessarily imply reduction of water use if food crops are produced, instead of livestock. For example, some grazing lands are unsuitable for food crop production, so that evapotranspirational water use would continue on land vacated by livestock, while additional water would be needed for crops to provide substituting food from lands elsewhere, and additional water would also be needed to produce substitutes for the non-food products of livestock. (In the US, Land Capability Classes V, VI and VII contain soils unsuited for cultivation, much of which is suitable for grazing. Of non-federal land in the US, about 43 percent is classed as unsuitable for cultivation.) 

Irrigation accounts for about 37 percent of US withdrawn freshwater use, and groundwater provides about 42 percent of US irrigation water. Irrigation water applied in production of livestock feed and forage has been estimated to account for about 9 percent of withdrawn freshwater use in the United States. Groundwater depletion is a concern in some areas because of sustainability issues (and in some cases, land subsidence and/or saltwater intrusion). A particularly important North American example where depletion is occurring involves the High Plains (Ogallala) Aquifer, which underlies about 174,000 square miles in parts of eight states, and supplies 30 percent of the groundwater withdrawn for irrigation in the US. Some irrigated livestock feed production is not hydrologically sustainable in the long run because of aquifer depletion. However, rainfed agriculture, which cannot deplete its water source, produces much of the livestock feed in North America. Corn (maize) is of particular interest, accounting for about 91.8 percent of the grain fed to US livestock and poultry in 2010. About 14 percent of US corn-for grain land is irrigated, accounting for about 17 percent of US corn-for-grain production, and about 13 percent of US irrigation water use, but only about 40 percent of US corn grain is fed to US livestock and poultry. Together, these figures indicate that most production of grain used for US livestock and poultry feed does not deplete water resources and that irrigated production of grain for livestock feed accounts for a small fraction of US irrigation water use. However, where production relies on irrigation from groundwater reserves, water table monitoring is appropriate to provide timely warning if groundwater depletion occurs.

Effects on aquatic ecosystems

In the Western United States, many stream and riparian habitats have been negatively affected by livestock grazing. This has resulted in increased phosphates, nitrates, decreased dissolved oxygen, increased temperature, turbidity, and eutrophication events, and reduced species diversity. Livestock management options for riparian protection include salt and mineral placement, limiting seasonal access, use of alternative water sources, provision of "hardened" stream crossings, herding, and fencing. In the Eastern United States, waste release from pork farms have also been shown to cause large-scale eutrophication of bodies of water, including the Mississippi River and Atlantic Ocean (Palmquist, et al., 1997). However, in North Carolina, where Palmquist's study was done, measures have since been taken to reduce the risk of accidental discharges from manure lagoons; also, since then there is evidence of improved environmental management in US hog production. Implementation of manure and wastewater management planning can help assure low risk of problematic discharge into aquatic systems. (See Animal Waste section, below.)

Greenhouse gas emissions

Farmer ploughing rice paddy, in Indonesia. Animals can provide a useful source of draught power to farmers in the developing world

At a global scale, the FAO has recently estimated that livestock (including poultry) accounts for about 14.5 percent of anthropogenic greenhouse gas emissions estimated as 100-year CO2 equivalents. A previous widely cited FAO report using somewhat more comprehensive analysis had estimated 18 percent. Because this emission percentage includes contributions associated with livestock used for the production of draft power, eggs, wool and dairy products, the percentage attributable to meat production alone is significantly lower, as indicated by the report's data. The indirect effects contributing to the percentage include emissions associated with the production of feed consumed by livestock and carbon dioxide emission from deforestation in Central and South America, attributed to livestock production. Using a different sectoral assignment of emissions, the IPCC (Intergovernmental Panel on Climate Change) has estimated that agriculture (including not only livestock, but also food crop, biofuel and other production) accounted for about 10 to 12 percent of global anthropogenic greenhouse gas emissions (expressed as 100-year carbon dioxide equivalents) in 2005 and in 2010.

A PNAS model showed that even if animals were completely removed from US agriculture and diets, US GHG emissions would be decreased by 2.6%(or 28% of agricultural GHG emissions). This is because of the need to replace animal manures by fertilizers and to replace also other animal coproducts, and because livestock now use human-inedible food and fiber processing byproducts. This study has been criticized, however. Further study on the matter has suggested that farmers would reduce their land use of feed crops; currently representing 75% of US land use, and would reduce the use of fertilizer due to the lower land areas and crop yields needed. Scientific literature appears to suggest that GHG emissions do not correspond linearly with nutritional capacity, and that a reduction, rather than elimination of animal based food, would provide optimum nutrition and minimal GHG emissions. A transition to a more plant based diet is also projected to improve health, which can lead to reductions in healthcare GHG emissions, currently standing at 8% of US emissions.

In the US, methane emissions associated with ruminant livestock (6.6 Tg CH4, or 164.5 Tg CO
2
e in 2013) are estimated to have declined by about 17 percent from 1980 through 2012. Globally, enteric fermentation (mostly in ruminant livestock) accounts for about 27 percent of anthropogenic methane emissions, and methane accounts for about 32 to 40 percent of agriculture's greenhouse gas emissions (estimated as 100-year carbon dioxide equivalents) as tabulated by the IPCC. Methane has a global warming potential recently estimated as 35 times that of an equivalent mass of carbon dioxide. However, despite the magnitude of methane emissions (recently about 330 to 350 Tg per year from all anthropogenic sources), methane's current effect on global warming is quite small. This is because degradation of methane nearly keeps pace with emissions, resulting in a relatively little increase in atmospheric methane content (average of 6 Tg per year from 2000 through 2009), whereas atmospheric carbon dioxide content has been increasing greatly (average of nearly 15,000 Tg per year from 2000 through 2009).

Mitigation options for reducing methane emission from ruminant enteric fermentation include genetic selection, immunization, rumen defaunation, outcompetition of methanogenic archaea with acetogens, introduction of methanotrophic bacteria into the rumen, diet modification and grazing management, among others. The principal mitigation strategies identified for reduction of agricultural nitrous oxide emission are avoiding over-application of nitrogen fertilizers and adopting suitable manure management practices. Mitigation strategies for reducing carbon dioxide emissions in the livestock sector include adopting more efficient production practices to reduce agricultural pressure for deforestation (notably in Latin America), reducing fossil fuel consumption, and increasing carbon sequestration in soils. Australian scientists discovered that adding the seaweed Asparagopsis taxiformis to the cattle's diet can reduce methane by up to 99%, and reported a 3% seaweed diet resulted in an 80% reduction in methane.

Testing Australian sheep for exhaled methane production (2001), CSIRO.
 
In New Zealand, nearly half of [anthropogenic] greenhouse gas emission is associated with agriculture, which plays a major role in the nation's economy, and a large fraction of this is assignable to the livestock industry. Some fraction of this is assignable to meat production: FAO data indicate that meat accounted for about 7 percent of product tonnage from New Zealand's livestock (including poultry) in 2010. Livestock sources (including enteric fermentation and manure) account for about 3.1 percent of US anthropogenic greenhouse gas emissions expressed as carbon dioxide equivalents, according to US EPA figures compiled using UNFCCC methodologies. Among sheep production systems, for example, there are very large differences in both energy use and prolificacy; both factors strongly influence emissions per kg of lamb production.

According to a 2018 study in the journal Nature, a significant reduction in meat consumption will be "essential" to mitigate climate change, especially as the human population increases by a projected 2.3 billion by the middle of the century. A 2019 report in The Lancet recommended that global meat consumption be reduced by 50 percent to mitigate climate change.

Effect of air pollution on human respiratory health

Meat production is one of the leading causes of greenhouse gas emissions and other particulate matter pollution in the atmosphere. This type of production chain produces copious byproducts; endotoxin, hydrogen sulfide, ammonia, and particulate matter (PM), such as dust, are all released along with the aforementioned methane and CO
2
. Furthermore, elevated greenhouse gas emissions have been associated with respiratory diseases like asthma, bronchitis, and COPD, as well as increased chances of acquiring pneumonia from bacterial infections.

In addition, exposure to PM10 (particulate matter 10 micrometers in diameter) may produce diseases that impact the upper and proximal airways. However, farmers aren’t the only ones at risk for exposure to these harmful byproducts. In fact, concentrated animal feeding operations (CAFOs) in proximity to residential areas adversely affect these individuals' respiratory health similarly seen in the farmers. Concentrated hog feeding operations release air pollutants from confinement buildings, manure holding pits, and land application of waste. Air pollutants from these operations have caused acute physical symptoms, such as respiratory illnesses, wheezing, increased breath rate, and irritation of the eyes and nose. That prolonged exposure to airborne animal particulate, such as swine dust, induces a large influx of inflammatory cells into the airways. Those in close proximity to CAFOs could be exposed to elevated levels of these byproducts, which may lead to poor health and respiratory outcomes.

Energy consumption

Data of a USDA study indicate that about 0.9 percent of energy use in the United States is accounted for by raising food-producing livestock and poultry. In this context, energy use includes energy from fossil, nuclear, hydroelectric, biomass, geothermal, technological solar, and wind sources. (It excludes solar energy captured by photosynthesis, used in hay drying, etc.) The estimated energy use in agricultural production includes embodied energy in purchased inputs.

An important aspect of energy use of livestock production is the energy consumption that the animals contribute. Feed Conversion Ratio is an animal's ability to covert feed into meat. The Feed Conversion Ratio (FCR) is calculated by the taking the energy, protein or mass input of the feed divided by the output of meat provided by the animal. A lower FCR corresponds with a smaller requirement of feed per meat out-put, therefore the animal contributes less GHG emissions. Chickens and pigs usually have a lower FCR compared to ruminants.

Intensification and other changes in the livestock industries influence energy use, emissions and other environmental effects of meat production. For example, in the US beef production system, practices prevailing in 2007 are estimated to have involved 8.6 percent less fossil fuel use, 16 percent less greenhouse gas emissions, 12 percent less water use and 33 percent less land use, per unit mass of beef produced, than in 1977. These figures are based on analysis taking into account feed production, feedlot practices, forage-based cow-calf operations, backgrounding before cattle enter a feedlot, and production of culled dairy cows.

Animal waste

Water pollution due to animal waste is a common problem in both developed and developing nations. The USA, Canada, India, Greece, Switzerland and several other countries are experiencing major environmental degradation due to water pollution via animal waste. Concerns about such problems are particularly acute in the case of CAFOs (concentrated animal feeding operations). In the US, a permit for a CAFO requires implementation of a plan for management of manure nutrients, contaminants, wastewater, etc., as applicable, to meet requirements under the Clean Water Act. There were about 19,000 CAFOs in the US as of 2008. In fiscal 2014, the United States Environmental Protection Agency (EPA) concluded 26 enforcement actions for various violations by CAFOs. Environmental performance of the US livestock industry can be compared with several other industries. The EPA has published 5-year and 1-year data for 32 industries on their ratios of enforcement orders to inspections, a measure of non-compliance with environmental regulations: principally, those under Clean Water Act and Clean Air Act. For the livestock industry, inspections focused primarily on CAFOs. Of the 31 other industries, 4 (including crop production) had a better 5-year environmental record than the livestock industry, 2 had a similar record, and 25 had a worse record in this respect. For the most recent year of the five-year compilation, livestock production and dry cleaning had the best environmental records of the 32 industries, each with an enforcement order/inspection ratio of 0.01. For crop production, the ratio was 0.02. Of the 32 industries, oil and gas extraction and the livestock industry had the lowest percentages of facilities with violations.

With good management, manure has environmental benefits. Manure deposited on pastures by grazing animals themselves is applied efficiently for maintaining soil fertility. Animal manures are also commonly collected from barns and concentrated feeding areas for efficient re-use of many nutrients in crop production, sometimes after composting. For many areas with high livestock density, manure application substantially replaces application of synthetic fertilizers on surrounding cropland. Manure was spread as a fertilizer on about 15.8 million acres of US cropland in 2006. Manure is also spread on forage-producing land that is grazed, rather than cropped. Altogether, in 2007, manure was applied on about 22.1 million acres in the United States. Substitution of animal manure for synthetic fertilizer has important implications for energy use and greenhouse gas emissions, considering that between about 43 and 88 MJ (i.e. between about 10 and 21 Mcal) of fossil fuel energy are used per kg of N in the production of synthetic nitrogenous fertilizers.

Manure can also have environmental benefit as a renewable energy source, in digester systems yielding biogas for heating and/or electricity generation. Manure biogas operations can be found in Asia, Europe, North America, and elsewhere. The US EPA estimates that as of July 2010, 157 manure digester systems for biogas energy were in operation on commercial-scale US livestock facilities. System cost is substantial, relative to US energy values, which may be a deterrent to more widespread use, although additional factors, such as odor control and carbon credits, may improve benefit /cost ratios.

Effects on wildlife

Grazing (especially overgrazing) may detrimentally affect certain wildlife species, e.g. by altering cover and food supplies. However, habitat modification by livestock grazing can also benefit some wildlife species. For example, in North America, various studies have found that grazing sometimes improves habitat for elk, blacktailed prairie dogs, sage grouse, mule deer, and numerous other species. A survey of refuge managers on 123 National Wildlife Refuges in the US tallied 86 species of wildlife considered positively affected and 82 considered negatively affected by refuge cattle grazing or haying. Such mixed effects suggest that wildlife diversity may be enhanced and maintained by grazing livestock in some places while excluding livestock in some places. The kind of grazing system employed (e.g. rest-rotation, deferred grazing, HILF grazing) is often important in achieving grazing benefits for particular wildlife species.

Some scientists claim that the growing demand for meat is contributing to significant biodiversity loss as it is a significant driver of deforestation and habitat destruction; species-rich habitats, such as significant portions of the Amazon region, are being converted to agriculture for meat production. Nearly 40% of global land surface is being used for livestock farming.

Effects on antibiotic resistance

Approximately 90% of the total use of antimicrobials in the United States was for non-therapeutic purposes in agricultural production. Livestock production has been associated with increased antibiotic resistance in bacteria, and has been associated with the emergence of microbes which are resistant to multiple antimicrobials (often referred to as superbugs).

Beneficial environmental effects

Among other environmental benefits of meat production, is the conversion of materials that might otherwise be wasted, to produce high-protein food. For example, Elferink et al. state that "Currently, 70 % of the feedstock used in the Dutch feed industry originates from the food processing industry." US examples of "waste" conversion with regard to grain include feeding livestock the distillers grains (with solubles) remaining from ethanol production. For the marketing year 2009-2010, dried distillers grains used as livestock feed (and residual) in the US was estimated at 25.5 million metric tons. Examples with regard to roughages include straw from barley and wheat crops (feedable especially to large-ruminant breeding stock when on maintenance diets), and corn stover. Also, small-ruminant flocks in North America (and elsewhere) are sometimes used on fields for removal of various crop residues inedible by humans, converting them to food. 

There are environmental benefits of meat-producing small ruminants for control of specific invasive or noxious weeds (such as spotted knapweed, tansy ragwort, leafy spurge, yellow starthistle, tall larkspur, etc.) on rangeland. Small ruminants are also useful for vegetation management in forest plantations, and for clearing brush on rights-of-way. These represent food-producing alternatives to herbicide use.

Education reform

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