Chicken metabolism,immobilization,and post-industrial production

Abstract

Chickens have become emblematic of the Anthropocene: They embody the age of acceleration, (post-) industrial value, and intensification in scientific and technological knowledge and practice. Contemporary chickens are the bearers of significant genetic and nutritional knowledge, experimented upon and ‘tweaked’ so much so that some have denied that contemporary commercial chickens are chickens at all. This article reconsiders chickens through a metabolic lens, and the notion of metabolism through chickens, arguing that attending to chickens opens up new conceptualizations of life and labour in the metabosphere. The article tells a metabolic history of chickens from ornament to enclosed monocrop, by way of the laboratory and nutritional experiments. Then, it looks at chicken metabolism in three conceptual modes: first, as a conduit for value, metabolizing and enhancing human life for the past century; second, through technological innovations extending the gut outside chickens’ immobilized bodies; and third, through the planetary impacts of metabolic porosity in geological manifestations, toxic atmospheres, and viral overflow. Ultimately, this article shows how techno-scientific production of chickens has taken place in and created the metabosphere as a site of experimentation and exploitation.

Much has been made of contemporary chickens. Their growth rates are increasing year on year (Jaap, 2007) and these accelerated chickens are central to the production of cheap food. For Patel and Moore (2017) the chicken nugget can be seen as a sign of the Anthropocene era. Chickens have been part of the industrialization and expansion of a nutrition transition rooted, according to Otter (2021), in a British appetite for meat. The chicken has been theorized as akin to a sentient flesh—a body that accumulates value through its embodied labor of growth (Beldo, 2017)—and the scales and environments of chickens remain fertile spaces for exploration around scientific, geological, and conceptual questions. Chickens’ industrialization has been read as a signal of a human-reconfigured biosphere as an element of the Anthropocene epoch, complete with a new strata of chicken bones (Bennett et al., 2018). Contemporary chickens are the products of significant genetic and nutritional transformation across industrial bodies, realized through processes of biological metabolism. The industrialization of chickens has aligned with global shifts in human nutrition, and chickens have been used to subtly enhance the human diet, through nutritional additions (Boyd, 2001), and through the intensification of production, growing ever more and ever larger chickens to feed a growing taste for these birds.

This article looks at chickens through a metabolic lens, and conversely at metabolism through chickens, arguing that attending to chickens and their metabolisms opens new conceptualizations of more-than-human life and labor. It does so by following the history of chickens and metabolism from the nineteenth century to the present (and future), following scientific literature on changing metabolic frontiers. I argue that through chickens, metabolic processes have been controlled, monitored, and manipulated, intensively fine-tuning chicken labor as a synthesizer of nutritional value for humans—and that these processes are still emergent. I conceptualize metabolism as a theory, practice, and politics. Chicken metabolism has been converted into processes of the transformation of matter, and the chicken body has become a conduit for adding value. My empirical analysis uses historical and scientific literatures to tell the story of chickens through their metabolic transformations, casting them as a vital actor in scientific and technological understandings of nutrition, labor, and body.

Conceptualizing metabolism through chickens

Over the past decade, the concept of ‘metabolism’ has grown in popularity across the social sciences and social theory, used to explore and theorize processes of, for example, the city (Newell & Cousins, 2014) and urban development (Barles, 2010). As Levin (2014, p. 557) puts it, metabolism is a site of complexity, a ‘complicated internal process that is the result of multiple pathways’ that is also informational and statistical, rooted in data. This surge in interest in the metabolic has emerged simultaneously with a turn in the agricultural sciences and practice to the importance of gut health in sustainable and efficient production systems (Wilson & Situ, 2017). Where this previous work takes the concept of metabolism as a metaphor, in the case of chickens, I focus on non-metaphorical metabolisms, marking an extension and departure for metabolic thinking. This section outlines how this article takes up metabolism as concept, practice, and politics, drawing on work across STS and the social sciences.

In an intellectual history of metabolism, Wachsmuth (2012) traces the root of metabolic thinking to the 19^th century, when it was taken up by biology and biochemistry to characterize organic breakdown in individual organisms. In being taken up in social thought, Wachsmuth argues, metabolism has formed three distinct ecologies: (1) as a concept that can be historicized and followed in the field as it produces technocratic ideas of the body (Landecker, 2013), (2) as a model to understand human processes, such as cities or societies, through a systems lens focused on the movement of energy and matter (Wolman, 1965), and (3) as a political theory used mostly metaphorically and often in a Marxist tradition to think about labor and the dissolution of society-nature dualism (Keil & Boudreau, 2006). This article engages with metabolism as socio-ecological crisis, resting upon the premise of ‘metabolic rift’ as underpinning socio-ecological uses of metabolic thinking. In understanding chickens through metabolic thinking, this article also draws on Landecker’s historicization of metabolism’s travels. This article thus approaches metabolism through chickens and, conversely, chickens through metabolism, using these two traditions to understand how metabolism is not only a metaphorical concept, but a practice and politics playing out in the bodies of billions of chickens.

In his 1999 article ‘Marx’s theory of metabolic rift’, Foster challenges the idea that environmentalism is at odds with Marxism in sociological theory. Taking up metabolic rift as crucial to understanding ecological crisis under capitalism, Foster argues that this concept should be crucial for environmental sociology: Marx ‘went a considerable way toward a historical-environmental-materialism that took into account the coevolution of nature and human society’ (Foster, 1999, p. 373). Ultimately, for Foster, metabolic rift is a problem resulting from industrialization, and agricultural industrialization offers a particularly compelling case study for this environmental case. Moore (2017) pushes Marxist approaches to the environment further through his work on metabolic rifts or, more accurately, metabolic shifts. He argues that the ‘rift’ argument hangs on environmentalist tropes of separation, that suggest that humans and nature are somehow disconnected. Moore argues that Marxist metabolic thinking should instead be concerned with movement and relationality, positing that ‘metabolisms are always geographical. Capitalist relations move through, not upon, space, which is to say, through, and not upon, nature as a whole’ (p. 313). The metabolic rift concept, both as an industrial and a socio-ecological approach, can be seen acutely in the contemporary chicken, a bird whose intensification in agriculture has transformed its physiology, with consequences for the planet and, relatedly, worsening conditions of labor and health for humans and non-humans alike (as I discuss later in this article).

Schneider and McMichael (2010) understand the metabolic rift as a social, ecological, and historical concept, echoing the three ecologies of metabolism proposed by Wachsmuth (2012). In its ecological sense, metabolic rift engages with outdated understandings of agriculture and ecosystems that ignore the multiple forms of labor, both human and, I would add, non-human. Ultimately, they conclude that the social and ecological must be ‘reunified’ and complexified. This conceptualization of metabolic rift thus takes metabolism as a way of understanding socio-ecological crisis brought about by capitalism, industrialization and intensification of production systems that is continually reworked as systems themselves shift (Wittman, 2009), allowing for the continual pushing of natural limits, as novel technologies and systems are developed.

The relationship between nature and labor in Marxist metabolic thought can be extended to the labor of non-humans (e.g. Beldo, 2017). Biological and ecological processes have already been pushed to their presumed limits in contemporary agricultural systems, both in producing animal and plant foods (Goodman et al., 1987; Moore, 2015). The chicken is an exemplary and extreme case of this: Where chickens are immobilized, constrained by space and bred bodily limitations, these metabolic limits likely have been reached. Engaging with scientific literatures that understand and endorse the reaching of these limits while imagining new ones does not just ‘draw attention to extractive capitalism itself as a form of out-of-control, self-destructive metabolism’ (Chao, 2023), but can enable understandings of how non-human bodies are augmented and extended through metabolism as a political-scientific goal.

Landecker (2011), diverging from socio-ecological debates, writes a history of metabolism to illustrate how changing discourses of manufacturing and regulation affect understandings not just of bodies or environments, but of society. In the nutritional and agricultural sciences, metabolism is understood as ‘a dynamic web of cellular signals, built by and responding to environmental information, food molecules, or food pollutants’ (Landecker, 2013, p. 496). Metabolic processes are sites of environmental risk, management, and information, with different temporalities and in relation with external environments. In this conceptualization, material does not move through bodies in a linear fashion: It is broken up, stored, attached to other molecules, and moves (or does not move) in complex ways. Metabolic crises, such as the so-called ‘obesity’ epidemic (Monoghan et al., 2014), are therefore problems not of storage, but of regulation, by individuals and states through the writing of political and social ideology onto bodily processes and materialities (see Sanabria, 2016). Therefore, understanding how the concept of metabolism is known and practiced is also vital to fully appreciating the non-metaphorical conceptualization of chicken metabolisms.

In the agricultural sciences and industry, metabolism is central to practice: How can metabolism be enhanced? How can metabolic disease be avoided? And how can products be made with the lowest levels of consumption and land use intensification (Dang et al., 2021). It is from this scientific literature that I historicize and follow metabolism, drawing on models of other work in this vein, such as Blanchette’s (2020) work on pigs, which looks at how metabolism flows within and beyond the landscape of farms and slaughterhouse, and how the metabolic push towards rapid growth and efficiency passes through and across bodies—human and non-human (Blanchette, 2019). Chickens have been positioned as exemplars of this ruthless efficiency, pushing beyond the limits of nature (Moore, 2015), deploying metabolic exploitation through control of mobility, selective breeding, and biotechnological enhancements (Castanon, 2007). Broiler chickens have been used to illustrate the role of metabolic labor as an exploitation of life (Beldo, 2017), and this argument has been applied to think about metabolic work in other animals, such as pigs (Blanchette, 2020) and black soldier flies (Zhang, 2020). However, I show that the specific history of exploitation of chickens is essential to understanding metabolic control through (im)mobilization.

Across STS and the social sciences, explorations of chicken metabolism are being used to theorize novel productions of life and labor (Beldo, 2017), and as an exemplar of capitalism out of control (e.g., Patel & Moore, 2017). Chao (2023) has argued that metabolism is a ‘distributed mode of connection’ that ‘draws attention to the dynamics of absorption, ingestion, and transformation that alternately sustain or undermine organismic wellbeing across individuals and collectives’ that are constituted of humans, animals, plants, and ecologies. Metabolic processes are therefore not (only) embodied, but part of ecological processes. In this article, I use the history, present status, and future of chickens to understand how metabolism is being deployed and tweaked to transform, immobilize, and finally augment chickens—and in turn, life on earth itself. This follows STS moves to historicize, embody, and follow metabolism through bodies and ecologies, casting—chicken bodies as holders of endless and intensifying value and possibility. Accordingly, in the next section, I follow chickens from the industrial to the post-industrial by examining how ideas about and practices of metabolic exploitation have shifted over time.

The (post-)industrial chicken

Contemporary chickens—g. gallus domesticus—are global birds. First for cockfighting, then for showing, and finally for meat and eggs, ‘the chicken crossed the world because we took it with us’ (Lawler, 2016). In 2022, there were over 26 billion chickens worldwide (Statista, 2024), with the majority of them living and dying in intensive industrial systems. In a distribution map, Gilbert et al. (2015, fig 4., p. 9) found that while extensive chicken farming is still common in Africa (see Young, 2020), China and the rest of Asia are seeing an increasing amount of intensive chicken farming, as their food systems transition into clusters of high production zones like those that dominate the Americas and Europe. In this section, I draw on scientific literatures to tell the story of chickens through their metabolic transformation. By drawing on work across the social and natural sciences, I contend that framing chickens within a metabolic history allows for the rethinking of chickens as conceptual or analytical exemplars and vital actors in scientific and technological understandings of nutrition (see Boyd, 2001), labor, and the body.

Chickens were domesticated in northern China and other locations around 8000 BCE (Xiang et al., 2014, p. 17564), according to the analysis of ancient DNA in the earliest archaeological bones excavated in the area of Yellow River. In the fourth century BCE, Egypt was home to ‘a mass society which mastered the technology of large-scale [egg] incubation’ (Smith & Daniel, 1975, p. 14); incubators were built of clay brick over fires adjusted by attendants who turned eggs and maintained the correct heat, allowing for ten or fifteen thousand eggs to be incubated at once. Recent archaeological developments offer new evidence into the little-known early history of chickens in Europe, suggesting that they did not arrive until the first millennium BCE, and that there was ‘a consistent time-lag between the introduction of chickens and their consumption by humans (Best et al., 2022, p. 868). These claims imply that chickens ‘were initially regarded as exotic and only several centuries later recognized as a source of “food”’ (Best et al., 2022, p. 868). Their early history sees the antecedents of today’s mass production of chickens, yet predates the metabolic ‘rift’ (Moore, 2017) that anticipated the emergence of chickens for contemporary capitalism.

In more recent history, chickens and their eggs have been considered premier model organisms for science, from Darwin’s theory of evolution to contemporary genome sequencing (Burt, 2007; Derry, 2015a; NIH, 2004). The adoption of chickens into genetic experiments coincided with ‘the importation into the West of the giant Asiatic breeds’ (Smith & Daniel 1975, p. 205) and by the mid-nineteenth century, chicken breeding was a sophisticated endeavor drawing on chemical knowledge (Derry, 2015b). Parolini (2020) has argued that while agriculture has been an unpopular subject among historians of science and technology, the two are not so easily separated when thinking about technological innovation and the development of scientific practices. The rapid growth of chickens as efficient, fast sources of food was echoed in the growth of the industry, which also focused on speed, efficiency, and growth (Josephson, 2020).

By the mid-nineteenth century, chicken breeding was becoming big business, with poultry breeding for food, experimentation, and beauty evolving in tandem (Marie, 2008). Poultry shows started to sweep across the USA and Britain, the first held in London in 1845 (Dohner, 2001). The advent of specialized birds and breeding, ‘began the odyssey of the modern chicken propelled out of the obscurity of the barnyard onto the national and international scene, traded in and speculated on like a growth stock’ (Smith & Daniel, 1975, p. 208). Chickens, whether bred for beauty or productivity, were imbued in a politics of production in pursuit of the ‘ideal chicken’, and this pursuit remains vital to chicken business today. Miele (2011) has argued that the recent invention of free-range chickens as happier, more natural iterations of chicken against the monstrous vision of the modern broiler invokes these earlier chickens, but they have always been subject to metabolic augmentation through intensification.

Boyd’s history of agro-industrial chicken (2001) exemplifies how chickens were integral to the entangled history of agricultural chemistry and nutritional science, being used for experiments on essential nutrients for changing human diets. Human and chicken nutritional requirements are similar making this small, easily handled bird ideal for this kind of scientific experimentation. By the 1940s, ‘the nutrient requirements of chickens were known more precisely than any other commercial animal species’ (Boyd, 2001, p. 645). These experiments weren’t just on chickens, they were with them, seeking to synthesize the chicken into an efficient model that could consume and metabolize matter and, in the process, enhance it. Chickens were employed in a distinct kind of labor ‘occurring at macrobiotechnological and microbiotechnological levels’ (Beldo, 2017, p. 118) and this labor congealed in the flesh, eggs, and genome of these chickens, and their descendants today. Towards the mid-twentieth century experiments with chickens moved from quantitative to genetic, as discussed in the next part of this article, but experimentation continued and intensified within this metabolic frame. Importantly, in the early 20th century, these experiments weren’t only to enhance chickens as food, but rather to enlist their metabolic labor in knowledge production.

In the 1920s, researchers at the University of Wisconsin were experimenting with vitamin D to reduce disease and increase efficiency. They found that supplementing vitamin D in chicken diets prevented leg weakness and, a century later, chickens still consume a vitamin-enhanced diet to prevent bone abnormalities and skeletal weaknesses (Edwards, 2000). Cod liver oil was added to chicken feed (Boyd, 2001) and this nutritionally enhanced diet meant that the birds could be kept indoors for longer stretches of time, as they no longer needed to metabolize their vitamin D from sunlight. As well as strengthening chickens and increasing efficiency in agricultural systems, vitamin D-enhanced diets also produced higher levels of this vitamin in chicken eggs, which in turn supplemented and improved human diets (Mattila et al., 2011). This enhancing of eggs has been widely implemented as a quick fix for the large numbers of people who are vitamin D deficient (Barnkob et al., 2020). The reconfiguration of nutritional qualities of eggs that went together with increased efficiency and lower spatial requirements was important for the quality of food produced by the poultry industry, but it was also vital for understanding how metabolism worked, to be applied beyond interventions in the gut. These experiments in the eighteenth, nineteenth, and early twentieth centuries set the stage for metabolic intensification in agro-industrial settings.

These efforts created the conditions for the making of the modern chicken. The agricultural and scientific history of chickens has shaped their construction and enclosure, which emerged in conjunction with metabolic knowledge and experimentation. These historical frames contributed to the making of chickens into conduits for value in the post-war period, as the chicken industry moved away from entwined ornamental, medicinal, and food histories to a singular focus on the latter.

A conduit for value

With the industrialization of chicken farming in the mid-twentieth century, chickens were divided into ‘broilers’ for meat and ‘layers’ for egg production (Davis, 2009). Today’s broiler and layer birds are the result of fowl-breeding since 1900, when a mutation in the TBC1D1 gene (responsible for glucose) produced new strains of chickens (Rubin et al., 2010). In the post-war period, the broiler business grew in every way—birds themselves doubled in size, the number of birds soared, and the systems of production intensified, emerging from the USA as a flexible, just-in-time, system (Boyd & Watts, 1997) that has been exported across the world and continues to grow.

Since the mid-twentieth century, driven increasingly by market logics, farmers have sought out new ways to produce and raise profitable birds, using selective breeding and genetic manipulation to increase their productivity, while driving down costs through intensification. It has been argued that chickens have it ‘the worst’ in agriculture (Pollan, 2002, n.p.), though they receive different kinds of attention in socio-political scholarship than do other agricultural animals, such as ruminants—with more obvious climactic impacts and hence are embroiled in contentious debates about their future (Enticott, 2008; Folkers & Opitz, 2022). Chickens are compelling to think with at a systemic and conceptual level, which is especially pertinent in discourses around public health (McKenna, 2017) and food systems (Berson, 2019). Chicken has even been posed as a potential substitute for beef due to its lower carbon emissions (see, for example, Leahy, 2019) despite ethical, health, and environmental concerns.

In debates around the environment and future of food, the chicken of concern is usually the broiler, rather than the layer. However, the broiler and the layer have only in recent history been separated in this way, to either produce eggs or flesh. Prior to this, chickens had been required to lay and grow big enough to provide meat for a substantial meal; this remains the case in extensive agriculture systems today, which are mainly (but not only) concentrated in Africa (Gilbert et al, 2015; see Mwacharo et al, 2013, on history of African village chickens). The American idea of a meat bird birthed a race to produce an ideal ‘hybrid’ chicken, that strengthened the boundary between broilers and other chickens (Boyd & Watts, 1997), intimately tied to the US Chicken of Tomorrow Contest to breed bigger, better, hybridized birds (McKenna, 2018).

In the mid-20th century, the chicken business in the USA was turned on its head. Chicken meat had previously been the cheap byproduct of laying hens whose production had slowed down, or fattened cocks unnecessary for egg production. Laying hens had traditionally dominated chicken agriculture worldwide, but by the end of the 20th century, they were eclipsed by a broiler business emerging from a US system of intensive production (Davis, 2009). Egg consumption dropped in the second half of the twentieth century due to salmonella fears, but as a proportion of meat eaten by Americans, chickens rose from 23% to 43% (Davis, 2009), overtaking beef in 1990 (Boyd & Watts, 1997). The modern broiler that ushered in this intensification can be traced to the Chicken of Tomorrow contest of 1948 in the USA, co-hosted by the US Department for Agriculture and A&P stores. The contest ostensibly aimed to find chickens that could feed a growing population: transforming, through genetic selection, birds good for laying into ‘superior meat-type chickens [with] broader-breasts, bigger drumsticks, plumper thighs, and above all, more white meat … so that the consumer would eventually come to depend on the bird as a reliable kitchen staple’ (Coe, 2014). The contest’s real goal was to make chicken meat desirable (Laatsch, n.d.) and to enlist chickens more intensely in novel forms of metabolic labor.

The demands to produce cheap chicken have led to a century of multi-scalar manipulations on metabolism. At the genetic scale, selective breeding aims for ‘robustness’ (McKay et al., 2018). At the environmental scale, light exposure and access to space are manipulated to meet the productivity demands of capitalist temporalities (Oliver, 2022a). And, at the physiological scale, nutritional management experimentation pursues efficient growth rates. These metabolic experiments are at once rudimentary and sophisticated, relying on visions of metabolism as industrial (Landecker, 2013) and housed in the body of chickens. There is a long and rich history of theorizing and criticizing industrial agriculture with chickens and their eggs, notably as ‘factories’, beginning with Harrison’s (1964) Animal Machines. For Landecker (2011), the development of metabolic knowledge in nutritional science in the 19th century is tangibly connected with the industrial era, being focused on the conversion of matter from raw materials of nature to products of man. In the industrial era, Landecker argues, biological ‘metabolism was understood as a factor, a “singular inward laboratory”’ (2011, p. 170). These two eras are, then, not distinct, but bleed into one another, with elements of early metabolic studies still found in experiments with chickens and their eggs.

Omega-3 (n−3 PUFA) is a polyunsaturated fatty acid found in flaxseed, fish, and algae. It is an ‘ancient, human biology-attuned nutrient’ (McMichael, 2005, p. 710) which is involved in the development and maintenance of brain tissue and is helpful in preventing cardiovascular pathologies, and potentially stress, depression, and dementia (Bourre, 2005). The recommended intake of this fatty acid is rarely met in Western diets, leading to experiments to modify eggs’ Omega-3 profile through feed supplementation (Fraeye et al., 2012). When supplemented in hens’ food, Omega-3 doesn’t just pass through chickens to be realized in the same form in their eggs; rather, the process of metabolization makes the Omega-3 easier for humans to digest and synthesize. Chickens efficiently distribute the desirable nutrients throughout their tissues (Bou et al., 2009), including their eggs in a process that technology cannot yet match. In addition, dietary supplementation such as this is safer than transgenic modification or adding bioactive compounds to the final product. Via the metabolic labor of chickens and the tweaking of poultry diets in industrial settings, ‘the egg becomes a conduit—produced and tailored for human nutritional needs and desires’ (Oliver & Turnbull, 2021).

In industrial understandings of metabolism, food consumption is followed by biophysical processes to break down the food, nutrients are taken in and any excess becomes waste through excretion. This fit with wider ideas of the body as a factory in the twentieth century, but post-industrial knowledge ‘changed the paradigm of metabolism to one of the interconnected biochemical pathways located deep inside the body, in cells and organs connected through flows of blood and other fluids’ (Hardon & Smith-Morris, 2019, p. 777). The enhancement of eggs relies on these post-industrial metabolic processes, using storage and synthesis of material (Omega-3) to attach nutritional goods to bodily materials, diverging from the input-output system of vitamin D enhancements discussed in the previous sections. These experiments on chickens and their eggs take on and implement new metabolic knowledges in order to attach nutritional value to eggs as a product synthesized by chickens’ consumption and digestive processes. In so doing, eggs—and therefore human diets—were nutritionally enhanced through stomachs and reproduction, outsourcing the metabolic labor of nutritional synthesis from human bodies to chicken ones. This outsourcing of metabolic labor would see further intensification of the chicken through immobilization in the latter half of the twentieth century.

The contemporary global poultry sector can be directly traced to the American system of production beginning in the mid-century (Boyd & Watts, 1997). This system has attempted to perfect a system of flexible production that is both dynamic and experimental, aiming not just to produce cheap chicken, but to offer nutritional value and the outsourcing of metabolic labor. In the next section, I argue that metabolism has become an externality through the immobilization of chickens. Recent scientific experiments on efficiency have taken metabolism outside of the birds, through the production of conditioning environments (Landecker, 2011).

Environments of immobilization

Where metabolism is understood as a set of flows and attachments, these processes are not confined to the body (Mol, 2021). Rather, the metabolism is situated within, and responsive to, the body and its environment. This metabolic conditioning environment is multi-scalar, from the microbiotic (Lorimer, 2017) to the atmospheric (Landecker, 2011). The intensification of poultry systems over the last century has relied on housing systems that keep birds immobilized, to prevent them and burn and ‘misdirecting’ energy away from growth (Qotbi et al., 2011); at the same time, metabolic processes have had to become more mobile, with chickens consuming more feed and expected to synthesize new and expanding kinds of nutritional value. For chickens, metabolic conditioning relies on a system of metabolic mobility under conditions of immobility. This expands upon recent literature that theorizes and conceptualizes human immobilization and argues that through the case of the chicken, a more-than-human immobilization is emerging from and through metabolism and its environments, notably realized through the case of capitalist biosecurity regimes around avian influenza.

In contemporary metabolic theory, chemical conversions of food into energy have been replaced by understandings of ‘food [as] a conditioning environment that shapes the activity of the genome and the physiology of the body’ (Landecker, 2011, p. 167). Modern human malnutrition arises not only due to deficiency, but also via excess (McMichael, 2005) and today, the ‘challenge for nutrition science is to develop new understanding and strategies to enable a balance between promoting, equitably, the health of humans while sustaining the long-term health of the biosphere’ (McMichael, 2005, p. 706).

Attempts to control and enhance metabolisms have become more sophisticated through, for example, bioengineering (Girod et al., 2005). With the imagined optimization of metabolism through tweaking or abolishing metabolic pathways, metabolism has become a holistic process internal and external to bodies themselves, a change that ultimately aims to ‘truly mold efficient biofactories’ (Aslan et al., 2017, p. 3935). For chickens, the control of environments to enhance production and efficiency is a continuation of a century of intensification, but metabolism itself as a conditioning environment now shapes chicken lives and labor in more intimate ways than ever before, especially as gut health has become a growing concern in the poultry industry (Linden, 2013). This conditioning relies on a complex interplay of mobility and immobility to exert control over production, life, and labor.

The immobilization of chickens to mobilize metabolism builds on a lineage of experiments with chickens that have pushed towards increased efficiency in the poultry industry. But there are further experiments taking place not just in chicken bodies, but around them, in controlling their environments as a means of enhancing production. These experiments speed up physiological processes to align with industrial time (Oliver, 2022a).

For example, experiments using light to disrupt poultry metabolisms have been implemented in poultry sectors to elongate the productive hours and annual cycles of chickens. Sunlight, or UV light simulators, stimulates the pituitary gland, signaling to the ovaries to increase the production of follicle-stimulating hormones, first on chickens (Payne & Hughes, 1933) and later, on turkeys (Bacon & Cherms, 1967). As a result, on today’s industrial egg farms the lights are kept on for sixteen hours, mimicking long summer days to foster daily laying throughout the year (Turner et al., 2022). Light manipulations as metabolic enhancers continue to be studied: experiments with different colours and intensities of light have explored the physiological effects on laying and growth (Lewis & Morris, 2000), and on body weight gain and productivity (Akyüz & Onbaşilar, 2018). These experiments have been combined with the use of hormones and variable amounts of food, water, and minerals, as well as in conjunction with pharmaceutical interventions to induce molting (Wolford, 1984); uncontrolled molting is seen as a wasteful direction of energy away from growth.

One example of forced molting exposes chickens to 24 hours of continuous artificial light, followed by food deprivation for 14 days with 10 hours of light (UPC, 1998). Induced or forced molting has the sole purpose of extending ‘economically useful life’ while reducing the greatest cost to the poultry sector: feed (Bell, 1996, pp. 3–4). These controls (im)mobilize bodily processes (of molting) to redirect energy to efficient and productive metabolic processes. Immobilization more generally has been vital to the poultry industry, but through the metabolic lens, the specific character of contemporary immobilization is connected to crises within and beyond the production process.

The contemporary global poultry industry is facing multiple crises: labor shortages, health threats, antibiotic resistance, production time, product quality, and soaring food costs (Hafez & Attia, 2020), many of which were recently exacerbated by the coronavirus pandemic and associated supply chain impacts (Sattar, 2021). The industry’s reaction to these crises follows what Achtnich (2022) has recently called ‘accumulation by immobilization’ in relation to the lives of migrant laborers in Libya. Similar logics of confinement can be extrapolated to understand the extraction of value through metabolic labor in and by chickens. The resonant carceral and captive logics of human and animal enclosure have been theorized by Morin (2016, 2018) as ‘shared geographies and disciplinary regimes’ (2016, p. 1318) and by Acampora (2006) as a carceral milieux of the more-than-human (Haraway & Tsing, 2019). In the poultry sector, immobilization is being deployed through narratives of risk and safety as justification for creating metabolically efficient conditions, as can be illustrated through responses to and regulation of avian influenza.

Avian influenza is one of the greatest pandemic risks on the planet today. Concerns have been raised not only about its inevitability, but its potential severity (Peiris et al., 2007) and this concern has persisted for at least two decades. The most prevalent strain, H5N1, ‘can infect people, nearly all people are immunologically naive, and it is highly lethal’ (Bartlett, 2006, p. 141). Any outbreak in human populations could lead to a serious pandemic. In the past century, there have been several avian influenza outbreaks, notably, in 1918, 1957, and 1978, which were of different severity, but the sampling from the latter two outbreaks indicated that the virus had ‘had components of previous human viruses as well as avian viruses’ (Monto, 2005, p. 323). This morphing of the virus spells trouble, as it makes human-to-human transmission of the virus more feasible and likely, with variants of concern being found in nine countries in East Asia and Southeast Asia (Li et al., 2004). Avian influenza outbreaks are becoming more frequent and more severe, with 2022 seeing the worst outbreaks in wild bird populations, evoking a ‘new Silent Spring’ (Weston, 2022). However, it is the risk of human transmission and health that is seeing increasingly strict containment measures implemented on commercial flocks, with biosecurity becoming an essential responsibility for scientists and agriculturists (Porter, 2016). Those measures are not just biosecurity ones, but part of the direction of knowledge between animal life and death that made confinement possible (Blanchette, 2019). For chickens, the entrenching of immobilization into their environments is made through regulation under the guise of protection.

On 16 August 2022, an almost year-long Avian Influenza Protection Zone (AIPZ) was lifted in the UK. Just fifteen days later, on 31 August 2022, a regional AIPZ was back in place in Cornwall, Devon, the Isles of Scilly and parts of Somerset. By the end of September 2022, areas in the East of England were also under an AIPZ and bird-keepers across Britain were advised to ‘follow enhanced measures at all times to prevent the risk of future outbreaks’ (DEFRA & APHA, 2023). Government agencies warned that wild bird populations are carrying high levels of the virus and therefore posed risks to commercial and pet birds (Middlemiss, quoted in DEFRA & APHA, 2023). AIPZs are imposed under legislation called The Avian Influenza and Influenza of Avian Origin in Mammals (England) (No.2) Order 2006 and require any poultry—commercial or domestic—in these zones to be housed and totally separated from wild birds. Avian influenza spreads primarily through the feces of migratory water birds, putting the UK and Europe under threat through the winter season, but increasingly, the flu season is stretching into the summer months. In the commercial sector, this means flocks—even free-range birds—are housed in barns with no access to the outside.

Commercial chickens have been immobilized to accumulate value through metabolic growth, but immobilization has morphed into a form of protection of value in the face of biosecurity risks. Segregation serves a secondary purpose of ensuring that chickens do not become ‘waste’ in outbreaks, which have seen entire flocks killed and incinerated. Their immobilization throughout periods of risk ensures that they can continue to grow, rooted to the ground, becoming vegetal. No longer animals or even birds, in the immobilizing spaces of biosecuritized industrial agriculture, and thus of poultry and agricultural science, chickens are an undifferentiated mass, indistinguishable as individuals. Chickens are transformed into a vast monoculture imbued with logics of de-animalization and de-individuation (Oliver, 2022b). This conceptualization of chickens is also prevalent in discourses that present them as an analytical entry point into the embodiment of the Anthropocene (Coles, 2022). As Haraway and Tsing (2019) have contended, modern chicken farming is nothing short of a plantation system, with ‘environmental modernization, homogeneity, and control, developed on historical plantations’ (Davis et al., 2019).

Chickens’ immobilized bodies therefore are essential to the smooth working of industrial processes of manufacture and consumption. Critically conceptualizing chickens as plants is not metaphorical, nor an attempt to squeeze them into emerging Plantationocene narratives. Rather, the vast monocultures of enclosed, immobilized production of commercial chickens can be best understood as produced in the same ways as vegetal capital and labor (Ernwein et al., 2021) rather than those of more lively commodities (Collard & Dempsey, 2013). This shift from animal to plant-like life for chickens does not undermine their liveliness and intelligence or their active resistance to immobilization (Wadiwel, 2018); industrial agriculture’s attempts to treat chickens as vegetal life on vast plantations (Tsing et al., 2019) collapses a boundary between animal and plant.

Recent work in vegetal geographies and critical plant studies makes possible new understandings and empathies within this collapsed binary, for example, of the role of plants in feeling, seeing, sensing, and interpreting the world (Chamovitz, 2012) and as active, not passive, contributors to ecologies and lifeworlds (Ernwein, 2021). In the chicken plantation, conditions of immobilization for efficiency and biosecurity cuts off chickens from ecological worlds (Krzywoszynska, 2020) and subjects them to intense metabolic control. This, however, is not the sole agenda of the plantation; there is also a necropolitical agenda, one that makes metabolism an externality but also an environment of control, risk, and labor. In the next section, I build on the historical following of chickens through a metabolic lens earlier in the article, and the contemporary immobilization and vegetal life of chickens described here, to explore new frontiers emerging from and extending the metabolic frame beyond life and into post-productive extraction from chickens.

New frontiers in metabolic labor

The immobilization of chickens over the past century is interwoven with ecosystems of labor and risk, as exemplified in the biosecurity implementations seeking to avert interspecies transmission of avian influenza. The risk was also made visible during the coronavirus pandemic, when the chicken processing plant became ‘a hotspot for [viral] outbreaks, revealing [the] transspecies porosities and the connection between Covid-19 and low-paid work, class, race and gender’ (Oliver, 2021, p. 127). In this section, I look at the interplay of immobilization for biosecurity and the porosities of metabolic control that overspill from chicken plantations into wider necropolitical logics of animal agriculture. In so doing, I argue that the externalization of metabolism, in conjunction with the vegetal constructions of chickens, are showing no signs of stopping, as experimentation with chickens expands through new frontiers, here exemplified in the use of chickens in novel biotechnologies.

Animal agriculture is dirty work, and its often-isolated geographical locations associate the low-paid, racialized workers with the outskirts of society (Morin, 2016). The chicken business has seen much deskilling in its recent history, with human workers no longer cultivating poultry ‘husbandry’, under pressures to speed up chicken farming and processing (Stuesse & Helton, 2013). As Blanchette (2020) has argued, animal agriculture no longer relies on a rich set of skills to raise, feed, kill, and butcher an animal. The chicken business has moved away from extensive practices and into intensive ones that require less biological or ecological knowledge.

The animal body and the human body are divided into parts: On the disassembly line, their bodies become ‘pools of potential value … as differential biologies’ (Blanchette, 2020, p. 180). None of these parts are contextualized within the whole body, and even less so within ecologies. Chicken agriculture does not just require, but mandates, the immobilization of animals, while relying on the mobilities of human migration for abundant and cheap labor to raise and dispatch chickens (Stuesse, 2016). In contemporary agricultural work, these (im)mobilizations leak out into atmospheres and environments around sites of agro-industrial production.

In the commercial chicken farm, plantation logics organize the labor and the commodity (Haraway and Tsing, 2019). Through its extraction, exploitation, and technological integration of labor, the plantation is a place where ‘the human’ goes to die (Courtenay, 1965). The plantation, as Margulies (2019) and Davies (2018) have shown in India and the USA respectively, is an ongoing necropolitical space where ‘contemporary forms of subjugation of life to the power of death reconfigure relations among resistance, sacrifice, and terror’ (Mbembe, 2003, p. 39). It is also a persistent model of the spatial organization and racialization of labor (McKittrick, 2013). Chicken farms are spaces of fast and slow violence on human and non-human life, both within the system and in the polluted environments around farms and slaughterhouses (Caffyn, 2021; Reid, 2022). While the fast and explicit violence to chickens and workers is obvious and located in the farms themselves, the slow violence of the chicken farm is only recently being acknowledged. Through its leaky and toxic effects on environments, water and public health, it is akin to what Davies (2018, p. 1540) has described in relation to petrochemical pollution as ‘unlocatable, dispersed, and contested’.

The broiler chicken—through industrial expansion since the 1950s—has become a ‘near-synchronous global signal of change to the biosphere … morphologically, genetically, and isotopically distinct’ from domestic chickens of the past (Bennett et al., 2018, p. 9). But with billions of these birds raised for meat and eggs each year, new consequences are emerging from this chicken production system, most notably in their waste being written into the earth. The broiler chicken is now a distinct morphospecies from the domestic chicken and, as such, its fossilized bones are reforming the earth’s geological records (Bennett et al., 2018). As geologist Zalasiewicz (2018) puts it, ‘it has taken just decades to produce a new form of animal that has the potential to become a marker species of the Anthropocene—and the enormous numbers of these chicken bones discarded means that we are producing a new kind of fossil for the future geological record’. Being written into the earth is not just the fossilized bones of chickens, but with them, the necropolitical logics of the chicken Plantationocene.

The production of chickens produces a lot of waste, ‘excreta, feathers, spilled feeds and water, dead birds, broken eggs, wastewater, litter, slaughterhouse and hatchery wastes’ (Rahman et al., 2022, p. 491). Every year, each commercial layer produces 20kg of waste, made up of feed, carcasses, litter, blood, feathers, eggs, and bones (Mozhiarasi & Natajaran, 2022). Around 90% of this waste is spread on land close to poultry farms (Mozhiarasi & Natajaran, 2022), but improper disposal, such as burning, is a growing problem that releases noxious gases (Kumar & Prakash, 2020) that affect human health and affect surface and ground water (Raman & Narayanan, 2008). This waste has significant environmental impacts, with one of the largest concerns in the sector being ammonia (NH₃) production—which is related to changes in weather, temperature, and ground soils (Coufal et al., 2006). The biggest environmental concern emerging from an expanding poultry sector today is the production of ammonia (NH₃). When chickens consume protein in their diets, which is essential for ‘synthesis of body tissue, for that renovation and growth of the body’ (Beski et al., 2015, p. 47), they produce uric acid, which is converted in waste streams to ammonia. This ammonia has a foul odor, which can lead to environmental health concerns and complaints (Naseem & King, 2018), in addition to producing methane. The production and leakage of ammonia isn’t just an external problem: It also affects birds in these enclosed and tightly controlled metabolic systems, reducing growth rates and increasing disease (Kristensen & Wathes, 2007). Modern ventilation systems monitor the levels of ammonia and seek to reduce them, by allowing it out into the environment, to ultimately ensure chickens metabolic efficiency and productivity aren’t affected (Kristensen & Wathes, 2000). Ultimately, this increases external emissions to the environment, and associated negative impacts on ecosystems, environments, other animals, and humans (Naseem & King, 2018).

The need for control of these toxic atmospheres is produced by the push to efficiency of chickens through the externalization of metabolism. But these processes of intensification have environmental, animal, and human impacts. For the low-paid workers in constant contact with ammonia in these systems, these toxic atmospheres have material and immediate effects, particularly irritating mucous membranes in the upper respiratory tract, nose, and eyes (Santoso et al., 1999), creating lasting damage (Hartung & Schulz, 2011). Recent studies have found both acute and chronic respiratory illness in poultry workers, during and after time in poultry houses (Kirychuk et al., 2003), with ‘chronic cough, chronic phlegm, chronic bronchitis, and chest tightness higher in poultry workers and chicken catchers than the control and non-exposed blue-collar workers’ (Naseem & King, 2018, p. 15272; see also Morris et al, 1991; Zuskin et al, 1995). Ammonia production reveals the leakiness of attempts to enclose the metabolic system extraneous to the body, thereby reiterating that no metabolism can be wholly internal, but is embodied in these more-than-human metabolic interrelations.

While ammonia and noxious gases leak out of these metabolic control systems, there remains work to find new materials and sources of efficiency inside those systems. Metabolic controls are not simple modes of dietary manipulation or improvement: They externalize metabolism with spiraling and specific consequences for the human and more-than-human worlds that are in close—and distant—contact with them. In and through the metabolism of chickens, a planetary transformation has been quietly gaining pace, enhanced and enabled by experiments with metabolism. Excessive waste, however, is not just a problem. It poses, for biotechnology, yet another new opportunity rooted in chicken metabolism, in how to redirect this excessive waste produced by metabolic labor into useful streams of production. This can be seen most clearly in the rise of biotechnologies from these toxic waste streams offering supposedly clean solutions to these dirty problems.

At the beginning of the twentieth century, when genetic experiments with chicken metabolism were in transition from quantitative breeding to genomic manipulation, two German chemists, Fritz Haber and Carl Bosch, were developing a process that converted atmospheric nitrogen to ammonia through reactions with hydrogen under a metal catalyst (Appl, 1982). This made ammonia fertilizer widely available, which increased agricultural yields (Boerner, 2019). Ammonia was the answer to agricultural problems of inefficiency, but today the fossil-fuel based process is antithetical to desired ‘carbon-free’ futures (Smith et al., 2020). Agro-industrial emissions are on the rise (EEA, 2010), volatizing in soils into powerful greenhouse gas, nitrous oxide using poultry waste to fertilize land, as well as the improper disposal of ever-growing sources of waste. However, the expansion of the biofuel industry draws on the promise of a circular economy in a time of scarcity (e.g. de Carvalho Freitas et al., 2022) to offer the potential to turn this toxic waste into a product, and in turn is seeing a further extension of metabolic labor for chickens.

The problem of waste in the poultry sector has been addressed by extending metabolic processes of chickens into the soil, impacting human and non-human health. While broilers are mostly consumed for meat, there are still parts of their bodies (e.g. heads and feet) that are less economically viable, despite economies in Asia of, for example, chicken feet consumption (Almeida et al., 2013). Laying hens are generally considered undesirable for human consumption, although there are notable cultural differences in attitudes towards this (Fan & Wu, 2022). These laying hens are usually slaughtered and then converted into cheap reconstituted chicken products (Modi et al., 2004), pet food (Fan & Wu, 2022), or protein meal that is fed to broiler chickens to support growth (Lyons & Vandepopuliere, 1996). However, novel biotechnological ventures are advocating for whole or partial chickens to be used as biofuels, bioplastics, and bioactive peptides for medicine and cosmetics, subject to processing and purification (Fan & Wu, 2022). To make this unproductive waste more desirable, protein and fats are extracted from chicken bodies before being developed (Safder et al., 2020) and further transformed into useful and, crucially, economically valuable products. These products, which include food supplements such as gelatin, collagen, and antioxidants, as well as bioplastics and biofuels, have recast waste chickens as ‘simple but multifunctional’ materials that are ‘valorized’, and are sites for further research and investment (Fan & Wu, 2022). The metabolic value of chickens, then, is extending ever further, breaking them down into smaller components with the potential for larger scales of metabolic exploitation.

Putting to work poultry waste—or rather ‘bones, undeveloped eggs, offal, and feathers’—has been emphasized as an environmentally friendly and economically beneficial way of dealing with it (Chowdhury et al., 2021, p. 37860). But, as Winickoff and Mondou (2017) point out, the development of biotechnologies raise epistemic regulatory questions, in areas such as standardization of production, but also in the visions of the future that technologies like biofuels create. With chicken bodies becoming a key site of interest for biotechnological development, metabolic processes are once again being transformed and expanded in these new frontiers. Where the immobilization and growth of chickens have recently become a defining emblem of the Anthropocene’s history, present, and future, their roles in a changing world and techno-scientific practices is far from finished. Sold as a renewable resource, biotechnologies are made from material that has been deemed chicken waste, with the assumption being that chicken waste (disposed of bodies and body parts, as well as excreta) will just keep coming, pushing against promissory alternatives (Jönsson, 2016). The necropolitical agenda embedded in the renewability of chickens as a resource is simple: The vast plantations of vegetal birds can be packaged as a green renewable resource.

Conclusion

Chickens occupy an unenviable position at the nexus of metabolic efficiency, necropolitical exploitation, and plantation logics, becoming not just post-industrial, but post-animal. In this article, I have deployed a metabolic lens, a framing that has rescaled chickens from the cellular to the environmental, to understand how life and labor in the bodies of chickens have become vegetal. The first part of this article conceptualizes metabolism, which is followed by a history of the chicken as a scientific and metabolic object. In the following three sections, I in turn argue that (1) chicken metabolism has been augmented to synthesize value through the twentieth century, (2) metabolism is being (im)mobilized to pull value out of plantation chickens by recasting them as vegetal, and (3) novel biotechnologies from extend the frontiers of metabolism.

Throughout, I have argued that understanding and complexifying the metabolic life and labor of chickens offers a new perspective onto the lives of this incredible species, which has been and continues to be enrolled in augmentations and extensions of the capacities of its cells and bodies. However, metabolic systems in the poultry industry have been thought of as primarily closed and bound by bodies, but they are instead leaky, overflowing, and environmental. The externalization of metabolic control and work extends metabolic thinking with the chicken as a site and process not just of production or labor, but of the storage and mobilization of material, with the potential to augment and devastate humans, non-humans, and ecosystems. Understanding chickens within these scientific-historical contexts enables not only an analysis of new frontiers in metabolic experiments with chickens in biotechnologies, but also speaks to how they are part of and subject to metabolic environments, as well as how the chicken becomes an (im)mobilized metabolic environment.