Research conducted over nearly a century identifies clear connections between animal agriculture and environmental disruption. Livestock grazing has long been associated with biodiversity loss in plant and wildlife communities, the dispersal of invasive species, degradation of soil structure, and desertification (Daubenmire, 1940; Savory, 1983; Allen et al., 1991; Savory and Butterworth, 1999; Drewry, 2006; Harrison and Bardgett, 2010; Wirsenius et al., 2010; Alkemade et al., 2013). Cattle grazing and livestock feed production are responsible for >65% of the deforestation that has taken place in Brazil and other tropical and subtropical regions (Vale et al., 2019). Animal agriculture is an important source of ammonia, greenhouse gas emissions (GHG) [Parris, 2011; USEPA (U.S. Environmental Protection Agency), 2017; Food Agriculture Organization, 2019] and blue water withdrawals [USGS (U.S. Geological Service), 2005; Rotz et al., 2019]. Runoff from livestock and feed production operations are significant non-point aquatic contamination sources [Agouridis et al., 2005; USEPA (U.S. Environmental Protection Agency), 2017].

These obviously negative impacts contrast markedly with the natural historical record documenting the roles of herd forming ungulates in maintaining the functionality of grass- and rangeland ecosystems and the human cultures that have depended on these systems for hundreds of millennia (Oksanen et al., 1981; Frank et al., 1998; Baltica and Boskovica, 2015). Large ungulates are keystone species in wild grassland ecosystems globally, supporting higher trophic transfer efficiencies than herbivores in most other kinds of terrestrial ecosystems (Stuart-Hill and Mentis, 1982; Frank et al., 1998). An estimated 168 million ruminants, including 50–60 million bison roamed the grasslands of pre-Colombian North America, supporting enormous soil fertility, and biodiversity in the plant communities they grazed (Frank et al., 1998; Skarpe and Hester, 2010). Greenhouse gas production, particularly methane production, by these ungulates was equivalent to that produced by modern livestock [Smith et al., 2016; USEPA (U.S. Environmental Protection Agency), 2020]. Massive ungulate herds also grazed and in some cases continue to graze the grasslands of Eurasia and Africa (Janis, 2010) and although the carbon and nitrogenous gas produced by these mammals once raised GHG levels in the atmosphere, they are not known to have significantly altered global climate (Smith et al., 2016). These wild, herd-forming ungulates did, however, represent critical nutritional and cultural resources to pre-agricultural human societies.

One must ask why large ruminants that have so profoundly contributed to the fertility and well-being of terrestrial ecosystems and the humans who inhabited them, have today become anathema to human and environmental health. Certainly, domestication has not changed the anatomies or physiologies of herbivores in meaningful ways. It is unlikely, then, that the negative impacts of animal agriculture are due to the species being produced. It seems more likely that livestock management practices determine impacts. It should, therefore, be possible to mitigate at least some impacts of animal agriculture by modifying production practices.

In this paper I address the null hypothesis that the environmental impacts of animal agriculture, particularly those associated with the production of ruminant species, are independent of management. I used data from the technical literature and popular media in this investigation. The focus of the paper is on livestock management practices in industrialized countries, including but not limited to the United States, the United Kingdom, Canada, Australia and the European Union, as well as certain developing countries, such as Brazil. Comparisons were made between two very different management models. One of these is generally associated with the industrial model of agriculture and based on pasture management practices that will be referred to as “conventional grazing.” The other is consistent with the regenerative model of agriculture and a set of livestock management practices collectively referred to as “multi-paddock grazing” (MP). Throughout this paper I will use the abbreviation IC to refer to the industrial-conventional management collective and RM to refer to the regenerative-multi-paddock management collective. In many cases I will refer to a system by its collective management approach, i.e., IC or RM. However, there are times, particularly in the experimental literature, when the collective management approach is not specified but the grazing practice (e.g., conventional or MP) is. Furthermore, there are times when data from several grazing operations or experimental systems are considered together without specification of an overall or collective strategy. In these cases, I will confine my description to the grazing practice (conventional or MP) rather than collective approach (IC or RM). It is recognized that animal agriculture exists along a continuum of practices with many operations combining elements of both industrial and regenerative practice.

To be clear, a variety of “traditional” practices (as distinguished from conventional practices) are used to manage livestock on pastures and rangelands in both the developed and developing world. These vary along a continuum from relatively unmanaged seasonal grazing (e.g., traditional Scottish and Icelandic sheep farming) to carefully managed seasonal livestock migrations (e.g., African Maasai cattle herders; French mountain shepherds, see Meuret and Provenza, 2014). In this paper, I will not dwell on the many, often ancient, practices used by traditional herding cultures, particularly in the developing world. Many of these are under stress from anthropogenic (e.g., Mongolian herders) and environmental forces (e.g., Saami reindeer herders of Scandinavia; Changpa nomads of the Kashmiri high-ice deserts). They should become the focus of further research, as they contribute to both fertility and stress in agricultural landscapes. The focus of this paper, however, is on comparing conventional grazing within the context of the industrial agricultural model, and multi-paddock grazing as incorporated into the regenerative agricultural model.

Modern industrial agriculture originated in Europe and the United States during the mid-eighteenth century in parallel with the Industrial Revolution. All efforts in agriculture were focused on boosting production and efficiency to meet the growing demand for food created by the massive demographic shift from the countryside to emerging urban manufacturing centers (Pollard, 1981; Wiesner et al., 2015). After the first and second World Wars mechanization and the development of synthetic fertilizers approximately doubled crop production. Synthetic pesticides (e.g., DDT) permitted the creation of large-scale crop monocultures year after year (Kleppel, 2014; Bellis, 2018). During the second half of the twentieth century the Green Revolution brought selectively bred plant varieties, especially cereal grains, to the developing world (Borlaug, 1970, 2002), but possibly at an unsustainable cost in terms of fossil fuels use, synthetic fertilizer applications, and blue water withdrawals (Brown, 1970; Cribb, 2010; Shiva, 2016). Today, as genomics, artificial intelligence and other information technologies surge, a new revolution in industrial agriculture is underway. Its success will be measured by the role it plays in feeding an exploding human population in the face of climate change and resource decline.

Optimization of production is the focus of modern industrial animal agriculture. This is often accomplished by finishing livestock in confined animal feeding operations (CAFOs). While increasingly limited in Europe (Imhoff, 2010), CAFOs are widely used in the US. Typically, beef cattle are moved from grazing lands to the CAFO at ~6-months of age and are ready for slaughter 3–5 months later. Dairy cattle and swine may be confined during much or all of their lives. The CAFO maintains livestock at high densities. Energy rich rations consisting of silage and/or pelletized grains, are typical feeds. Growth stimulants, including hormones, as well as certain antibiotics delivered at sub-medicinal levels that stimulate citric acid cycle activity, are widely used in the US (less so, outside of the US) to increase the rate of weight gain (Pollan, 2006; Kleppel, 2014). The US Food and Drug Administration [FDA (U.S. Food and Drug Administration), 2013; FDA (U.S. Food Drug Administration), 2019] has tightened control over (but not banned) the use of antibiotics in animal feeds due to their role in the production of antibiotic resistant, pathogenic bacteria [Feingold et al., 2012; FDA (U.S. Food and Drug Administration), 2013; FDA (U.S. Food Drug Administration), 2019]. Although beyond the scope of this paper, CAFO practices, which reduce finishing times by 30–50% relative to finishing on pasture, have been criticized as inhumane and unsafe (Schlosser, 2001; Pollan, 2006; Ebner, 2017). Nonetheless, the industrial model of livestock production is the globally dominant meat production system, accounting for more than 80% of the meat produced in the United States (Schlosser, 2001; Ikerd, 2008).

Conventional livestock management which, in this paper, refers to the on-farm portion of livestock production, prior to movement to the CAFO, dovetails with the industrial model in its focus on specialization and monoculture, in its extensive use of chemical and other inputs and its reliance on grain-based or grain supplemented nutrition for ruminants, even when animals are on pasture. Stock densities on pasture tend to be relatively low and stock rotation (i.e., movement to fresh pasture) tends to be relatively infrequent (weeks to seasons) if it occurs at all. Overgrazing is common in conventional grazing systems and may be compensated for by supplementing with hay, silage and/or pelletized grain.

Regenerative agriculture focuses at least as strongly on the restoration and management of soil health and agro-ecosystem functionality as on production (Doran et al., 2002). Doran (2002) defines soil health as “… the capacity of a living soil to function within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health.”

Regenerative agriculture has its roots in the early to mid-twentieth century, beginning with the work of Howard (1940, 1947), Balfour (1943) and the emergent organic and (what became) the holistic management and sustainable agriculture movements of the 1960s and beyond. The regenerative approach is a response to evidence that soil health, functionality and quality have been lost or have deteriorated to the extent that much of the earth's arable soils are incapable of producing nutrient dense food and have lost the capacity to support essential ecosystem services (Pimentel et al., 1987; Crosson et al., 1995; Lal, 2001, 2019; Pimentel and Burgess, 2013; Montgomery, 2017). As such, regenerative operations frequently employ organic or “nature-based” practices (Brown, 2018) with the co-equal goals of producing nutrient dense food while restoring and managing environmental quality (Bouma, 2002; Jackson, 2002).

Pasture-based livestock production is key to regenerative farming and ranching. Pasture-based producers feed ruminant livestock primarily on forages, hay, and/or haylage. Omnivorous, non-ruminant livestock, such as swine and poultry, usually receive some grain-based feed supplements. Stock densities of ruminants in this system are usually 2–4 times higher than in conventional grazing systems and rotation to fresh pasture generally occurs every 0.5–3 days (Flack, 2016). A rotational cycle through a subdivided pasture system, or multi-paddock system, should require at least 30 days, but rotational cycles of 60 to >100 days are not uncommon (Gerrish, 2004). Rotational cycles can be adjusted to accomplish ancillary goals, such as invasive plant management, or to respond to changing vegetation, weather patterns (e.g., drought) or other variables (see Kleppel et al., 2011; Girard Cartier and Kleppel, 2015; Bishopp, 2020). Several workers have described these methods in detail, using such terms as holistic planned grazing, management-intensive grazing and intensive rotational grazing (Savory, 1983; Savory and Butterworth, 1999, 2016; Gerrish, 2004; Flack, 2016; Salatin, 2019). Collectively, they are referred to as multi-paddock (MP), or adaptive multi-paddock (AMP) livestock management (Teague et al., 2011; Rowntree et al., 2019). Multi-paddock management attempts to mimic the evolved herding behaviors of wild, ungulates (Voisin, 1959; Acocks, 1966a,b). Protagonists of multi-paddock management claim that this approach enhances soil fertility and health, reduces overgrazing, and reduces disease and morbidity within the herd. In this paper, I will examine some of these claims.

This paper compares IC and RM practice in four categories of environmental impacts associated with livestock agriculture. These are: (i) impacts to plant communities and soil health; (ii) impacts to water and soil-water interactions; (iii) impacts from agricultural ammonia (NH₃) emissions; and (iv) impacts associated with climate change.

From this brief review, it is evident that significant differences exist between the impacts of IC and RM management with respect to key ecosystem attributes. Though the issue is far from resolved, RM practices appear in many respects to be environmentally benign relative to their IC counterparts. The environmental impacts considered here, and the differences between the management practices that create them may not be the direct result of livestock activities on pasture or rangeland. Often, they are due to differences in the resource intensities (e.g., water or fossil fuels) required to support IC or RM management.

Papers published between the 1980s and the present have repeatedly questioned the efficacy of various forms of MP management, particularly Savory and Butterworth's (1999, 2016) holistic approach (e.g., Holechek et al., 2000; Briske et al., 2008; Hawkins et al., 2017; and others). Some of the hypotheses and observations promoted by Savory, such as the ability of holistic management to mitigate desertification and climate change (Savory, 2013) have been particularly contentious (Briske et al., 2013). However, Teague et al. (2009, 2013), Wang et al. (2016), and others (e.g., see Teague, 2014) have pointed to the technical and scaling issues that may influence the interpretation of the reductionist approaches typical of traditional experimental comparisons of livestock performance and their environmental consequences under IC management. It has also been suggested that contradictory results may accrue, at least in part, from perceptual differences in the management and operational goals of RM and IC management by both researchers and graziers (Briske et al., 2011). The contentiousness of the debate may contribute to its apparent un-resolvability (Collins, 1981). Briske et al. (2011) suggest moving beyond the debate over whether one management approach is better than the other. They suggest that the focus should be on finding adaptive approaches to livestock production and pasture/rangeland management that respond to the realities of meat production. Sherren and Kent (2019) decry the “linear” (i.e., reductionist) thinking that dominates the issue. The capacity of scientists to deal effectively with complex systems has long been problematic (Capra, 2005). Grazing ecosystems and the outcomes of herbivore-plant-soil interactions, while seemingly simple, are actually functionally complex (Liu J. et al., 2015). Sherren and Kent (2019) and Wynne (1992) point out that frequently researchers exclude or simply miss the realities of livestock management as experienced by graziers. Briske et al. (2011) and Gosnell et al. (2020) suggest incorporating multi-dimensional, socio-ecological perspectives into efforts to understand livestock management dynamics and its outcomes.

Traditionally, livestock farming, and ranching have had an overriding purpose: production (Toombs and Roberts, 2009). The determination of how to produce the greatest weight gain in the shortest amount of time is of interest to all farmers, ranchers, and students of animal science. Comparisons of livestock weight gain in MP and conventional grazing systems have not been consistent, and more than likely depend upon interactions among stocking rates, forage compositions and any number of highly variable environmental forcing functions as well as the spatial scales at which observations are made (Derner and Hart, 2007; also see Teague et al., 2013 for more detailed treatment of this subject).

Notwithstanding the importance of production, the slow but persistent emergence of the organic, sustainable, and regenerative farming movements have made environmental stewardship an additional, and even principal goal of animal agriculture. The practitioner's approach toward livestock management broadens when the focus of one's work includes land stewardship. Livestock is no longer the sole product. In fact, livestock becomes a tool to be used in the regenerative process. The convergent goals—production and stewardship—are not necessarily complementary and achieving one goal may impede achievement of the other, at least temporarily. For example, cattle produced by RM management often require 3–6 months longer to finish than grain-supplemented, pastured, or feedlot-finished cattle. However, RM practice may provide positive outcomes by improving soil health and forage quality, and by mitigating a substantial portion of total global GHG emissions.

It is common knowledge among both farmers and researchers that soil loss and grassland degradation are at near crisis stage (Pimentel, 1997, 2006; Montgomery, 2017; Brown, 2018; J. Kempf, pers. comm. 2017). It is not simply appropriate, but necessary, to the future of agriculture, that some of our attention be focused on soil and ecosystem regeneration. When one manages for soil health, water quality, GHG mitigation, biodiversity, and the restoration of other essential ecosystem services, as well as for livestock production, even the most fundamental management decisions will likely differ from those made when production is the only focus of one's practice. Consistent with the advice of Briske et al. (2011) and Gosnell et al. (2020), we must recognize that complex issues have only partial solutions in science, and that fuller and more satisfying solutions accrue by integrating scientific and practical knowledge (Sherren and Kent, 2019).

It is worth remembering that agriculture provides 98% of the food that humans consume, and that meat is critical to the global food supply (White and Hall, 2017). Two thirds of the land on which food is produced can only be used for meat production. If nothing else, this review has supported the concern of many that agriculture is the cause of significant environmental pollution, ecosystem stress, habitat destruction and the loss of ecosystem services. This must change; meat production must and can become a vehicle for creating protein sufficiency, environment integrity and the restoration of ecosystem services, globally. It is the very definition of a non-sequitur that: while food is a critical part of our life support system, to produce food we must destroy our life support system.

The results of the present analysis suggest that producing livestock need not destroy our life support system. RM practices, with their focus on the restoration and enhancement of ecosystems and the critical services they provide, appear to have the potential to make meat production a more environmentally benign process. Clearly, much is unknown. Data gaps remain; improvements in practice are needed and, in some cases, forthcoming. Supply chain models to ensure the economic viability of RM livestock production at scale are, at best, in the early stages of development. Adoption by farmers and ranchers remains limited, and policies and educational programs that encourage greater participation in RM practice are often lacking or poorly advertised (Francis et al., 1986). Efforts to discourage regenerative meat production by special interests and naivete within certain sectors of the research community have slowed development of sustainable meat production practices (e.g., Willett et al., 2019). Yet, given that meat consumption is increasing worldwide (NAS, 2015), adoption of environmentally regenerative meat production practices seems crucial.

Although enough food is currently produced to provide a calorically sufficient daily ration to every human being on earth, we are rapidly approaching carrying capacity (Cribb, 2010; Tilman et al., 2011). Within the next 30 years, as the human population approaches 10 billion, as the climate becomes increasingly hostile, as water, soil, biodiversity, and other resources disappear, it will become increasingly difficult to feed ourselves (Larson et al., 1983; Pimentel et al., 1992; IPCC, 2019). Although regenerative production will not slow population growth and will never, in and of itself, provide the solution to world hunger, agriculture, including animal agriculture, can play an important role in GHG mitigation, soil-health restoration, and water and biodiversity conservation (Lal, 2004; Herrero and Thornton, 2013; Sacks et al., 2014; Cassidy and Kleppel, 2017; Montgomery, 2017; Stanley et al., 2018). The effectiveness of agriculture as a tool, not only for feeding ourselves but for meeting the challenges posed by human population growth, and in the process providing a sustainable income to farmers and ranchers has been suggested by research and demonstrated in practice (Food Agriculture Organization, 2013; Kleppel, 2014; Teague and Barnes, 2017; Brown, 2018; Massy, 2018; Amadu et al., 2020). Livestock production represents a tool, not only for providing calories and protein to our species over the next half century, but for ensuring the livability of our planet to humans and myriad other species well into the future.

Ungulates are key to human nutrition and the functioning of Earth's ecosystems. Nonetheless, animal agriculture is a significant contributor to grassland degradation and soil destruction, water pollution and depletion, and global greenhouse gas emissions. It seems a non-sequitur that the production of food, part of our life support system, should be linked to degradation of the environment (i.e., our life support system). I reviewed the literature on two approaches to livestock management, one based on industrial agriculture, the other on regenerative agriculture, to ascertain whether one system is environmentally benign relative to the other. There is a lack of consensus on which approach is less destructive of plant communities or soil structure, though regenerative management appears to support larger, more diverse soil microbial communities. Furthermore, regenerative animal agriculture appears less likely to contribute to water pollution, to have lower water withdrawal requirements, and to be associated with lower greenhouse gas emissions and higher greenhouse gas removal rates than industrial management. By broadening the focus of animal agriculture to include both production and stewardship we can feed our species while reducing damage to the environment.

The author confirms being the sole contributor of this work and has approved it for publication.

The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.