Synopsis 

Within the livestock sector, beef emerges as the commodity receiving the most attention for its environmental impacts, whereas the benefits and nutrition values are each substantial. This is due to the evident aggregated contribution that beef production makes to global environmental issues such as climate change and land use. Globally, beef supply chains are estimated to emit about (2.9) two point-nine gigatonnes of CO2-eq, about (40%) forty percent of all livestock emissions using a life-cycle approach (Gerber, Henderson, Opio, Mottet, & Steinfeld, 2013). The greenhouse gas emissions per unit of product (emission intensity) peak where beef is produced on newly deforested land (Cederberg, Persson, Neovius, Molander, & Clift, 2011). Cattle are also the dominant ruminant species making use of about (1/4) one-quarter of all emerged lands (Bouwman, Van der Hoek, Eickhout, & Soenario, 2005; Steinfeld et al., 2006). These issues are augmented by public health concerns related to high meat consumption levels and pollution from intensive production (Walker, 2005) as well as growing attention to animal welfare (O’Donovan & McCarthy, 2002; Petherick, 2003). 

The world has over (1.3) one point three billion cattle about (1) one for every (5) five people on the planet (FAOSTAT, 2015). While cattle are kept and raised for the full range of products and functions they deliver, the vast majority is eventually culled and served as meat. Beef production thus takes multiple forms and involves a wide range of supply chains. The debate on beef production, and livestock more generally, is, however too often characterized by a lack of recognition of this tremendous diversity in production systems, in the goods and services they deliver as well as in the environmental interactions and measurable diversification options for improvement that exist (Smith, 2015). The general perception of beef production is incomplete as it is biased towards specialized factory farming. At the same time, these represent a limited part of a sector that is still dominated by family farms operating on mixed systems (Herrero et al., 2013). This paper aims at providing a global overview of beef production systems, their diversity, and their contributions to society. It also reviews how beef supply chains contribute to major global environmental issues and identifies specific entry points for intervention. 

Commentary 

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Analysis 

Interactions with the environment 

A large part of our ecosystem is managed for cattle production through a variety of practices and at a range of intensification levels. It is accordingly not surprising that the sector has strong and diversified interactions with the environment. Beneficiation occurs across regions and types of feed conducive to each climatic zone with its varying temperature range for which each breed that thrives has characteristics that are known with appreciation.

Land & Water 

Feed production, whether pasture or crops, is the main activity through which cattle use land and water resources (Steinfeld et al., 2006), which are efficiently consumed and convert into full-grown cattle. Over (60%) sixty percent of the global cattle feed ration (in DM terms) is made of grass and tree leaves (Fig. (3.)  three). Land occupancy related to the production of these materials (for all ruminants) is estimated at (1/4) a quarter of emerged land (Steinfeld et al., 2006), with management practices ranging from intensively managed pastures (planted and fertilized) to rangeland that is used occasionally depending on rainfall. The other (40%) forty percent are mostly crop residues (about (30%) thirty percent), which also include crop products and by-products. The global production of feed crops (for all livestock species) is estimated to mobilize about (1/3) one-third of the global cropped area (Gerber et al., 2013). While co-products are frequently used among mixed-systems, grains and by-products are mostly used in intensive dairy operations and feedlots.  

Co-products are generally sourced from industrial crop production, and thus which contribute to environmental issues such as eutrophication, water depletion and emission of pesticide into the environment (Tilman, Cassman, Matson, Naylor, & Polasky, 2002). The DM intake per unit of edible products is usually much higher for ruminants than monogastric (Bouwman et al., 2005). Furthermore, monogastric feed (mostly cropped) is less land-intensive than ruminant feed (mostly grass and tree leaves). This converges into relatively high land occupancy per unit of beef production compared to other livestock commodities. Based on a literature review, de Vries and de Boer (2010) report that in OECD countries, the production of (1) one kg of beef uses (30) thirty to (50) fifty m2, compared to areas inferior to (15) fifteen m2 for the production a kg of chicken, pork, egg or milk although it must be highlighted that the way the land is used is not the same. Land requirements per unit of beef vary significantly between regions (Fig. (5.) five). There is no apparent relation between the reliance on grassland/cropland and the land occupancy per kg of product.  

Grasslands dominate in all regions, but South Asia, where mixed systems relying on crop residues, are particularly common. Fig. (5.) five further shows regional trends in the place of imported feed. Off-farm land use is relatively essential in industrialized regions, also in North Africa and the Middle East. Mekonnen and Hoekstra (2012) estimated that beef cattle were responsible for (33%) thirty-three percent of the global water footprint of animal production and to almost (10%) ten percent of the worldwide water footprint of total agricultural production. Importantly though, these figures amalgamate different categories of water: blue water (diverted from surface and groundwater, usually for irrigation and servicing), green water (rainwater evaporated from soil and plants in rained crops and pasture) and gray water (needed to assimilate a load of pollutants, such as discharged manure and wastewater). Among these, it can be argued that green water consumption has virtually no environmental impact, given the fact that the natural ecosystem would have similar levels of evapotranspiration (de Boer et al., 2012).  

If the beef green water footprint largely surpasses those of pig and chicken meat (by a factor (3) three to (4) four), its blue and gray water footprints are actually of similar magnitude: (550) five hundred fifty and (451) four hundred fifty-one for beef respectively. Understandably this compares to (313) three hundred thirteen and (467) four hundred sixty-seven for chicken meat and (459) four hundred fifty-nine and (622) six hundred twenty-two for pig meat (Mekonnen & Hoekstra, 2012). Beyond these global averages, it is, however, the wide range of local situation that deserves attention: the same authors find gray water footprints ranging from (0) zero m3 per ton (Grazing systems in India) to (1,234) twelve hundred thirty-four m3 per ton (Industrial systems in China). Attention is also given to green water footprints ranging from (2,949) twenty-nine hundred forty-nine m3 per ton (Industrial systems in the USA) to (25,913) twenty-five thousand nine hundred thirteen m3 per ton (Grazing systems in India). Farm-level variability will be even higher than these averages at the country/system level. 

Nutrient Cycles 

Cattle are estimated to contribute (56 to 60%) fifty-six to sixty percent of the yearly (75 to 138) seventy-five to one hundred thirty-eight) Tg N excreted by all livestock species (Oenema, 2006). The relatively low efficiency of nutrient retention not only represents a significant economic loss but also places a burden on the environment (Sutton et al., 2013). In general terms, between (55 and 95%) fifty-five and ninety-five percent of the nitrogen (N) and about (70%) seventy percent of the phosphorus (P) ingested by livestock are excreted as urine or faces (Menzi et al., 2010). Part of this manure is recycled and fertilizes pastures and crops, but a large share is lost to the environment through gaseous emissions, leaching, and runoff (Castillo, Kebreab, Beever, & France, 2000; Eckard, Chapman, & White, 2007). Fig. (6) six illustrates the proportion of feed nitrogen retained by dairy and beef herds. Efficiencies are generally more significant in regions where feed is balanced and tuned to the needs of animals. They however hardly exceed (30%) thirty percent in the dairy herd and (15%) fifteen percent in the beef herd. Animal level efficiency measured on the productive animal is generally higher than herd level efficiency.  

This is confirmed by Fig. (7) seven for milked cows (which N efficiencies range between (15) fifteen and (35%) thirty-five percent, but not for beef animals, probably due to the limited representativeness of reviewed studies. P use efficiency is generally more significant, ranging between (19) nineteen and (60%) sixty percent for milked cows and between (14) fourteen and (28%) twenty-eight percent for fattening animals. Fig. (7) seven further shows that efficiency levels, although spreading over large ranges, are typically lower for cattle than for other species. This explains severe environmental impacts where feeding or dairy operations concentrate in confined geographical areas and nutrient excretions substantially exceed the absorption capacity of the land (Menzi & Gerber, 2006). Oenema (2006) reports N input-output budgets of 10, 115 and 126 kg/ha/year for extensive, grass-clover and fertilized grass-based beef systems of western Europe. Generally, the author reports that N losses per ha increase as we move from grazing systems to mixed operations and feedlots. 

GHG Emissions 

Livestock contributes to climate change by emitting greenhouse gases (GHGs) either directly (e.g., from enteric fermentation and manure management) or indirectly (e.g., from feed-production activities, conversion of forest into pasture). Based on a life-cycle assessment (LCA) approach, it is estimated that the sector emits about (7.1) seven-point one gigatonne of CO2 equivalent, about (14.5%) fourteen-point five percent of the total anthropogenic GHG emissions (Gerber et al., 2013). Cattle are the main contributor to the sector’s emissions with about (4.6) four point six gigatonnes of CO2-eq, representing (65%) sixty-five percent of sector emissions. Beef cattle (producing meat and non-edible outputs) and dairy cattle (producing both meat and milk, in addition to non-edible outputs) generate similar amounts of GHG emissions. Beef contributes (2.9) two-point nine gigatonnes of CO2-eq or (41%) forty-one percent and cattle milk (1.4) one point four gigatonnes of CO2-eq or (20%) twenty percent of total sector emissions. 

When emissions are expressed on a per protein basis, beef is the commodity with the highest emission intensity (amount of GHGs emitted per unit of output produced), with an average of over (300) three hundred kg CO2-eq per kg of protein. Followed by meat and milk from small ruminants, with averages of (165) one hundred sixty-five and (112) one hundred twelve kg CO2-eq per kg of protein, respectively (Fig. (8) eight). Different agro-ecological conditions, farming practices, and supply chain management explain the considerable heterogeneity observed both within and across production systems. There is a distinct difference in emission intensity between beef produced from dairy herds and specialized beef herds. The emission intensity of beef from specialized beef herds is almost fourfold than that produced from dairy herds ((68) sixty-eight vs. (18) eighteen) kg CO2-eq per kg of carcass weight) (Gerber et al., 2013). This difference is primarily because dairy herds produce both milk and meat while on the other hand, specialized beef herds mostly produce beef.  

As a consequence, emissions from dairy herds are attributed to milk and meat, while emissions from beef herds are allocated to meat (in both cases, a limited fraction is allocated to other goods and services, such as draft power and manure used as fuel). A closer look at emission structure shows that emissions from reproductive animals (the “breeding overhead”) exclusively explain the difference. When only fattening animals are considered, specialized beef and surplus dairy calves have similar emission intensity per kg of carcass weight. In addition, the breeding cohorts represent (69%) sixty-nine percent of the herd in specialized beef herds compared with (52%) fifty-two percent in dairy systems. 

Biodiversity 

Biodiversity is considered as an impact located at the endpoint of environmental mechanisms. It means that the interactions between beef production and the ecological categories described above – GHG emissions, nutrient cycles, land, and water use have, in turn, an impact on biodiversity. Several pathways of impact on biodiversity exist and importantly, they range from negative to positive effects. Because of its essential land use, beef production modifies many habitats. One type of habitat modification is the destruction of undisturbed habitats, as the conversion of the Amazonian rainforest to pastures and feed crops (soybean in particular). Amazonian rainforests are biodiversity hotspots; they may host up to a quarter of the world’s terrestrial species (Dirzo & Raven, 2003). The destruction of this habitat led to significant biodiversity losses, although it is recognized that beef production is not the only driver of deforestation, which has been significantly reduced since 2004. The second type of habitat modification is land degradation. It results from the combination of improper grazing management (overgrazing in particular) and climatic factors. Depending on regions, land degradation leads to desertification or woody encroachment, both accompanied by biodiversity losses (Asner, Elmore, Olander, Martin, & Harris, 2004). 

The third type of habitat modification yields a positive biodiversity effect: the maintenance of semi-natural grassland habitats. In Europe, grassland habitats are among those with the highest biodiversity levels because the long history of livestock farming provided time for a large pool of species to adapt and specialize (Bignal & McCracken, 1996). Extensive and appropriate grazing management is key to maintaining these habitats and their rich biodiversity. When abandoned, they “close” into shrubland and ultimately forests which often have lower conservation value. Beef production has a significant contribution to this type of extensive management, and its positive effect on biodiversity has also been evidenced in other regions (e.g., China, the US). Mixed and industrial beef production systems could also have a positive impact on biodiversity if intensifying the production was a way to spare undisturbed habitats for biodiversity conservation.  

However, specific intensification practices would have to be adopted to mitigate the other types of the adverse effect that these systems can have on biodiversity, through pollution in particular. Moreover, intensification does not automatically lead to spare land for biodiversity conservation; robust policy frameworks are thus necessary (Ewers, Scharlemann, Balmford, & Green, 2009). Climate change is an increasingly important driver of biodiversity loss; Thomas et al. (2004) estimated that (15) fifteen to (37%) thirty-seven percent of the species in their global studied sample would be “committed to extinction” by 2050 due to climate change. Although beef production has a significant contribution to anthropogenic GHG emissions, isolating its responsibility in the biodiversity loss due to climate change would be complicated. The link between nutrient pollution caused by beef production is more direct. In industrial to a mixed system, such pollution occurs at several stages of livestock production. Upstream, it is related to the fertilization of feed crops.  

A striking example is the nutrient loading in the Mississippi River due to extensive fertilizer use in the central US croplands (mainly used as animal feed), which leads to hypoxia and ‘dead zones’ in the coastal ecosystem. Biodiversity loss from eutrophication can also originate from the farm level, where livestock concentration and a large amount of nutrient excreted pose a challenge for manure management (Carpenter et al., 1998). In mixed systems, there is a vital biodiversity loss associated with the transition from natural to fertilized grasslands. Conversely, manure excreta in pastoral systems can have an essential role in nutrient cycling and benefit biodiversity (Gibson, 2009). Another type of pollution related to beef production arises from the use of ecotoxic substances. At the feed cultivation stage, the use of pesticides can have direct adverse effects on non-target plant and arthropod species, and lead to a decline of species at higher trophic levels because their food resources are rarefied (e.g., birds).  

Arthropod species suffering higher mortality due to pesticides include pollinators, which could result in losses of agricultural production. At the animal husbandry stage, pollution by an ecotoxic substance can result from the use of veterinary products (e.g. antibiotics, anthelmintics, hormones). These substances can affect aquatic and soil biodiversity, as well as on insects and scavenger species (Boxall, Sarmah, & Meyer, 2002). Reciprocally, biodiversity can also have an influence on beef production. High plant species richness in grassland is correlated with higher biomass production, as well as carbon storage and resistance to weed invasions (Finn et al., 2013). Inter-specific differences in maturity and nutritive value also lead to a more stable digestibility of forage along the grazing season. In rangelands, biodiversity is essential for the resilience of pastoralist systems as heterogeneous landscapes can provide resources in a broader range of climatic situations. 

Conclusion 

The interactions between beef supply chains and the environment span over the entire spectrum of global environmental concerns and are specific to each production system. Table (3) three provides a broad-brush overview of these interactions. No production systems perform better than the others in absolute terms. Maintaining a diversity of systems inadequacy with the diversity of agri-environmental conditions and societal needs, identifying specific interactions, risks, and opportunities as well as implementing the necessary improvements in each system will, therefore, be essential to improve performance. Interventions that have been shown to improve livestock and environment interactions are numerous. Strategies need to be tailored to local conditions and constraints and the combination of several practices and technologies (i.e., technical packages) is often required to achieve significant improvement (Mottet et al., forthcoming).  

One may, however, recognize three essential principles for interventions. First, aim for improved natural resource use efficiency, defined as the number of natural resources engaged per unit of product. This is an objective of global relevance, which applies to the most affluent areas of the globe, where the sector is requested to minimize its environmental impact, and to emerging economies, where livestock production expands rapidly in a context of relatively weak environmental policies and often wastes natural resources. It is equally relevant to the poorest regions of the world but from an opposite perspective. Here, there is a need for maximizing production out of limited resources (Gerber, Uwizeye, Schulte, Opio, & de Boer, 2014). Second, tap into the substantial improvement potential that lies in the heterogeneity of environmental performance among production units, even within production systems. As documented by Thoma et al. (2013) for US dairy farms, the vast diversity of management practices and technologies used on production units translates in significant differences in environmental impacts.  

There is thus a substantial potential to improve the environmental performance of the sector by fostering the broader adoption of best practices and thus narrowing the environmental performance gap. Gerber et al. (2013) modeled that such an approach could reduce global livestock GHG emissions intensity by about one third. Third, the need to focus on continuous improvement, acknowledging that environmental sustainability is a relative state, which depends on the overall level of human activities, on the status of resources and availability of technologies. This principle is also influential in providing development pathways for all producers and stakeholders along supply chains, irrespective of their initial practices. Guiding continuous improvement, however, requires to be equipped with fair and accepted indicators. Here is a clear role for science to generate metrics and methods to monitor and benchmark environmental performance on a range of issues. 

A particular challenge to the sustainability of beef supply chains is the existence of multiple trade-offs between environmental interactions. This is further complicated by the vast range of other sustainability challenges that the sector faces, rooted in issues such as public health (diets, food safety, and antimicrobial resistance), food security, equity, economic growth, and animal welfare. These elements often closely relate to environmental interactions and need to be addressed comprehensively. When addressing the ecological performance of livestock production, it is essential to keep in mind the ultimate needs of a society that are met by the system in question: the roles played by cattle are particularly wide-ranging and beyond just providing food. Science is a key to identifying solutions to mitigate these trade-offs, i.e., to make improvements on one dimension at lower costs on other aspects. In parallel to science, there is a need for constructive dialogue towards an agreement on the relative priority given to these competitive goals.  

Science-based dialogue is essential to the development of effective policies and practice change. Examples of processes facilitating such kind of dialogue are the Global Agenda for Sustainable Livestock (http://www.livestockdialogue.org) and the Global Round Table for Sustainable Beef (http://grsbeef.org). Table (4) four proposes a simplified overview of these challenges and opportunities and how they translate into different entry points and opportunities for intervention aiming at increased environmental sustainability. In pastoral systems, environmental impacts per unit of products are generally high but absolute consequences are low because of the small production volumes. Livestock is the main asset communities can rely on to live in harsh environments characterized by an erratic biomass production. The capacity to innovate is limited by the prime obligation of resilience and the need to avoid risks inherent to any practice change. In these conditions, environmental outcomes can hardly be prime objectives in themselves.  

Sustainable natural resources management should be addressed as a means to productivity and resilience and environmental outcomes as co-benefit. Feedlots, on the contrary, serve the middle-class consumers in an urban area. They mostly developed as an effective way to respond to a demand for beef expressed by a food secure population. Given the strong capacity of feedlot operators to invest and innovate, environmental outcomes may well be sought as objectives. Furthermore, given the strong growth of these systems, impact intensity should be addressed in combination with overall impacts to avoid missing aggregated effects. In-between, beef production in mixed methods (including dairy and beef herds) have generally lower environmental impact intensity but an enormous overall impact given the sheer size of the cattle population in these systems. Livestock is integrated with crops and contributes to agricultural productivity and diversification.  

Poor resource use efficiency is, however a constraint to productivity and environmental performance. Improving efficiency is thus a key entry point and an incentive for change. This review confirmed the significant contribution the beef sector currently makes to environmental issues and its critical role in the development of sustainable food systems. It identified practical interventions that can improve environmental sustainability and highlighted the need to disentangle the diversity of beef supply chains and understand them in their specific functions and context to design appropriate interventions. To be sustainable, the sector needs to respond to the growing demand for livestock products and enhance its contribution to food and nutritional security; provide secure livelihoods and economic opportunities for hundreds of millions of pastoralists and smallholder farmers; use natural resources efficiently, address climate change and mitigate other environmental impacts; and enhance human, animal, and environmental health and welfare.  

Consequently, policy and management interventions need to best reconcile the various demands concerning productivity, sustainability, and societal values, for now, and the future and they should be tailored to regional and local specificities. Therefore, please follow us on social media and join us on the (1^st) first and (15^th) fifteenth of each month for our fortnightly delivery of insightful, informative must-reads from some of the world’s scientific thinkers. Selected by our editors is a collection of current topics with a profound ability for beneficial improvements, guidelines, and process practices. Thank you for reading our publication entirely; please share it with others who also care. We look forward to your comments and having you with us again fortnightly; we will be thrilled in having you with us; thus, we will take your trust in us with great honor and appreciation.