Synopsis 

Beef makes a substantial contribution to food security, providing protein, energy, and essential micronutrients to human populations. Rumination allows cattle and other ruminant species to digest fibrous feeds that cannot be directly consumed by humans; thus, an extraordinary ability exists to make a net positive contribution to food balances. This contribution is of particular nutritional importance in marginal areas, where agro-ecological conditions and weak infrastructures do not offer many alternatives. It is also valuable where cattle convert crop residues and by-products into edible products and where they contribute to soil fertility through their impact on nutrients and organic matter cycles. At the same time, environmental sustainability issues are acute. They chiefly relate to the low efficiency of beef cattle in converting natural resources into edible products.  

Water use, land use, biomass appropriation, and greenhouse gas emissions are for example, typically higher per unit of edible product in beef systems than in any other livestock system, even when corrected for nutritional quality. This mainly causes environmental pressure when production systems are specialized in the delivery of edible products in large volumes. The paper discusses ecological challenges at a global level, recognizing the vast diversity of systems. Beef production is faced with a range of additional sustainability challenges, such as changing consumer perceptions, resilience to climate change, animal health, and inequities in access to land and water resources. Entry-points for environmental sustainability improvement are discussion items and resources within this broader development context.  

Commentary 

This limited series of the occasional e-letters are comprised of (2) two articles. They will appear fortnightly and are published during August, though they will be accessible through our social media pages. 

Analysis 

Cattle: their biology, diversity, and related comparative advantages 

The specificity of ruminant production (mostly cattle, buffalo, sheep, and goat), its contribution to human societies, and its interactions with their environment are deeply rooted in the biology of ruminants. Three features stand out: digestion, reproduction, and diversity. 

Digestion 

The digestive track physiology determines the feed materials that animals can effectively utilize and the efficiency with which nutrients in feed materials are used. Ruminants are well known for their ability to digest feed materials rich in cellulose and fiber (low in energy content and typically only (50–65%) fifty to sixty-five percent digestible, in contrast to monogastric species (e.g. pig and poultry) (Fig. (1.) one). This is made possible by the microbial fermentation that occurs in the rumen. The products of this fermentation are absorbed by the animal in the following small intestines. This makes ruminants able to develop in conditions where monogastric species are excluded and places them in a unique position to turn resources inedible by humans into high-value food products but also other product outputs such as fiber, fertilizer, and draft power. 

The energy-efficiency of microbial fermentation is, however, limited by the emission of enteric methane (CH4). It is estimated that about (8–12%) eight to twelve percent of the energy in a feed is lost through methane and cannot be utilized by animals (Huysveld et al., 2015). This is an issue for the producer, also for the environment given methane’s global warming potential. Similarly, ruminants are not particularly efficient in using high-quality dietary proteins: a high share is broken down in the rumen and partially used for microbial growth, resulting in ammonia exhalation and losses of N in feces (Opio, Gerber, & MacLeod, 2013). 

Reproduction 

Reproduction performance (driven by fertility, prolificacy, and mortality among offspring) is a crucial driver of population dynamics and thus, of productivity, essential to the replacement of milked cows and to the production of young animals for fattening. However, a cow is likely to produce at best a single calf per year and commonly produces a viable calf every (1.5 to 2) one-point-five to two years (Ball & Peters, 2004). This is much lower than for other ruminant and non-ruminant species that are generally more fertile and prolific (Table (1.) one). In addition, cows typically become fertile at a later age than females of other species. This results in a more significant share of the animal herd that is dedicated to reproduction (the “reproduction overhead”), compared to other species, and therefore an increased part of the metabolizable energy that is dedicated to maintenance at the herd level. Combining this data allows one to conclude with estimations that between (50) fifty and (80%) eighty percent of total metabolized energy is used for maintenance (Opio et al., 2013). Further effects of late age at first calving, and relatively limited fertility and prolificacy are the slow nominal growth of herds. Particularly problematic is this nominal growth after a crisis that may have caused drastic falls in animal numbers, and the reduced pace at which new genes can be introduced into the herd. (Ball & Peters, 2004). 

Diversity & Hardiness 

Cattle and buffalo breeds represent (25%) twenty-five percent of the world’s (10,512) ten thousand five hundred and twelve recorded mammalian livestock breeds, a similar share than sheep, followed by horses, goats, and pigs, all-around (12 to 14%) twelve to fourteen percent. A comparison, only (3,505) three thousand five hundred and five-dollars avian breeds are reported, of which chicken represents (60%) sixty percent (FAO, 2007). Thousands of years of migrations and trade spread domesticated animals from their original habitats, exposing them to new agroecological conditions. South Asian Zebu cattle were, for example, introduced in Latin America during the early twentieth century and now support most of the production in this significant producing and exporting region (FAOSTAT, 2015). Natural selection and human-controlled breeding gave rise to the tremendous genetic diversity observed today (FAO, 2007). In all areas of the world, reported mammalian breeds to outnumber avian breeds (FAO, 2007). This enormous diversity reflects a tight adaptation of mammals, and cattle, to their environment and the needs of the human populations looking after them.  

Resistance to diseases (e.g. to trypanosomiasis), tolerance to particularly harsh climatic conditions allow varied species existence.  Conditions remain harsh for all though poor feed quality is among the traits that have placed cattle, together with small ruminants, in a position to sustain livelihoods and human settlements where crop agriculture and other mammalian and avian species could not. In more favorable agro-ecological conditions, selection among and within breeds, as well as the use of crossbreeding to exploit heterosis, have allowed reaching high levels of productivity and quality. The attributes are expressed in daily weight gains, conformation and fat to muscle ratio (Cundiff, Gregory, Koch, & Dickerson, 1986). Differentials illustrate an example, McKay, Rahnefeld, Weiss, Fredeen, and Lawson (1989) have reported that the live weights of cows can vary from 488 kg for a crossbred Hereford × Angus to 594 kilograms of a crossbred Charolais × Angus. This compares, for example, to the live weight of female zebu cattle varying from 162 to 207 kg in Nigeria (Mukasa-Mugerwa, 1989).  

In parallel to these breeding programs, the conservation of traditional cattle breed diversity is also receiving increased and now accelerating attention to halting the erosion of livestock genetic resources, which is recognized across borders as crucial for food security, rural development, and agriculture sustainability (FAO, 2007). There are now a higher number of food products under this category which breed conservation which is often conducted in association with the preservation of cultural and historical aspects of rural life and landscapes. The Global Plan of Action for Animal Genetic Resources (GPAAGR), (Hoffmann, 2011; Hoffmann & Scherf, 2010) has been adopted by (109) one hundred nine countries and includes (23) twenty-three strategic priorities for action to promote the wise management of these vital resources. Animal physiology and genetics of breeds are strong determinants of the potential performance of animals, especially concerning digestive and reproduction capacities. It is, however, animal management practices and technologies that determine the actual level of productivity and environmental impact. 

Cattle Production Systems & Contribution to Food Security 

Cattle production occurs within a myriad of different agro-ecological conditions and production systems, relying on diverse breeds and producing a range of goods and services. Understanding these differences in production practices is necessary for assessing the contribution of different methods and unraveling environmental interactions, as well as proposing development pathways (Bouwman et al., 2005). The type and source of feed given to the animals and particularly the share of grazing in the feeding system, are vital determinants of this diversity. Herd management and the level of market integration further contribute to the defining of production systems. 

Grazing Systems 

Sere and Steinfeld (1996) defined as grazing the systems where more than (90%) ninety percent of dry matter (DM) fed to animals comes from rangelands, pastures, and annual forages, and less than (10%) ten percent of the total value of production comes from non-livestock farming activities. Grazing systems supply about (34%) thirty-four percent of global beef production. They cover the largest land area, across all climatic zones. The most extensive forms of grazing systems have developed in a harsh environment, such as drylands and cold regions. Production is often mobile to make use of sparse and erratic resources and relies on communal land (pastoral and nomadic systems). Cattle herds in these conditions serve a diverse large number of functions, supplying food, but also transportation, fiber, banking, and insurance. Herd structure is adapted to deliver this multi-functionality and to buffer against shocks and crises. For example, animals are usually kept longer than in other systems. They also spend more energy on movements. Results of the analysis are a perspective and consequently, for example, productivity is generally low in terms of edible products; at animal level (even correcting for the relatively lightweight of animals), and especially at herd level (Opio et al., 2013).  

Average daily weight gains, milk yields, and age at first calving are typically low while mortality is high. Their market integration is further limited by deficient transport and communication infrastructure. The estimation of the total supply of these systems is to account for less than (15%) fifteen percent of total beef production (own calculation, based on FAO, 2009). While they adapt well, they have traditionally been resilient to harsh climate with scarce and erratic resources. These systems face issues in adapting to new challenges such as competition for resources with sedentary agriculture, political instability, even lack of representation in a modern institution, and climate change (Touré, Ickowicz, Wane, Garba, & Gerber, 2012). More intensive grazing systems are found in tropical and temperate zones where high-quality grasslands and fodder production can support more significant numbers of highly productive animals. These systems mostly focus on food production, based on individual land ownership and are well connected to markets. They supply about (20%) twenty percent of global beef production. 

Mixed Systems 

Mixed farming systems are defined as those systems in which more than (10%) ten percent of the dry matter fed to animals comes from crop by-products or stubble or where more than (10%) ten percent of the total value of production comes from non-livestock farming activities (Sere & Steinfeld, 1996). Gerber et al. (2013) further divide mixed systems in those that produce both milk and meat (“dairy herd”) and those that only produce meat (“beef herd”). Mixed methods account for the bulk of cattle population (over (60%) sixty percent) and a similar share of beef output. These figures are in line with those estimated by Herrero et al. (2013). On a global scale, the dairy and beef herds contribute equally to the beef output, however, significant regional variation exists, and the milking herd dominates beef outputs in regions such as Western Europe or South Asia. Notations should be made that dairy farms operating at relatively high levels of intensification are classified here as mixed systems. 

Feedlots 

In contrast to mixed and pastoral production systems, feedlots are almost exclusively dedicated to food production, as a response to the growing demand for beef in urban areas. The vast grain supply is the majority source of feed for feedlot feed that is purchased off-farm: beef cattle in feedlots are mostly fed on purchased grain, sometimes up to (95%) ninety-five percent in DM (70 to 90%) seventy to ninety percent in the U.S.). Feedlots are also characterized by high energy rations and high daily weight gains. The operations are usually generally operating the same way, large in size, fully mechanized and vertically integrated. There is a commonality in greater uniformity of technology and practices than in mixed and grazing systems. Feedlots are often coupled with diverse or grazing methods, from which they acquire young animals (weanlings or yearlings) for fattening until they reach a standard weight for slaughter. Today about (2%) two percent of the global cattle population is estimated to be held in feedlots and produce about (7%) seven percent of the worldwide beef production (the latter includes animals previously on other production systems).  

Beef production from feedlots is expanding throughout the world (Fig. (2.) two). Feedlots are well established in countries like the U.S. or Canada, and rapidly growing in other regions, such as South America, Asia, and Africa, driven by rising demand for meat in urban areas. Feedlots provide the kind of standardized carcasses requested by the retail sector and make use of relatively abundant crop products and co-products as well as by-products such as soybean cakes and Dried Distillers Grains with Soluble’s (DDGS). Feedlots usually have high animal performance levels in terms of daily weight gain and feed conversion ratio. This often results in relatively high levels of natural resource use efficiency (Capper, 2012; Pelletier, Pirog, & Rasmussen, 2010), although typically lower than industrial poultry and pig operations. Feedlot operations are nevertheless associated with relatively high impacts on water resources and air quality, mostly due to the geographical concentration of production units (Vasconcelos, Tedeschi, Fox, Galyean, & Greene, 2007).  

Farming system classification is a convenient and effective way to structure our analysis and recommendations. It is, however important to keep sight of the tremendous diversity that exists within our broad system classification, inclusive of the dynamics that do exist between classes. First, the transition is taking place from grazing to mixed systems, often driven by population density, but generally at limited pace, constrained by agro-ecological conditions and access to finance, markets and technology. Intensification within mixed systems and from combined methods to feedlots is quite faster (Bouwman et al., 2005), especially where market demand is strong, feed available and environmental regulations favorable. 

Contribution to Food Security 

The authors propose the following (5) five essential determinants to explain the level of contribution that cattle make to food security: 

First, the feed ration of the animals, and whether the materials included in the ration are used or produced in concurrence with plant-based human edible food. This is, for example, the case of grains and fodder crops cultivated on arable land. On the contrary, crop residues, food by-products and fodder produced on non-arable lands are not directly comestible by humans, although they could contribute to food production through fertilization and energy production. Fig. (3.) three shows the estimated composition of the global feed ration of cattle. Although it can be argued that a part of the “fresh grass and hay” is actually, grown then produced on cropland, the vast majority of the ration is made of materials not edible by humans. Second, is the efficiency with which the herd converts feed into edible products (kg of feed per kg of beef). This efficiency is driven by (i) the quality of the feed, (ii) the animal performances (e.g. growth rates, influenced by genetics and health conditions), (iii) the proportion of breeding stock in the herd (these animals need to be fed but do not contribute directly to the edible product output); and (iv) the proportion of meat supply from dairy herds, since in the dairy herd, maintenance energy is diluted over the two products.  

Looking at Fig. (4.) four), feed conversion can be expected to be poor, where maintenance drains a large part of the metabolized energy. Third, is the contribution cattle make to agricultural productivity, e.g., through manure and draft power used in crop production. Advancing these illustrations are, for example, Gebresenbet and Kaumbutho (1997) which estimate that cattle, together with camels, horses and donkeys, provides transport and draft power for plowing fields for about (15%) fifteen percent of farms in Southern Africa and (81%) eighty-one percent of farms in Northern Africa. In Europe, the share of manure input in total Nitrogen inputs was estimated at (38%) thirty-eight percent and reached (61%) sixty-one percent in the Netherlands (European Commission, 2012). Fourth, the availability and affordability of other sources of foods and in particular protein and micro-nutrients, and thus the essential or optional nature of the beef contribution to nutrition. Resulting achievement is the production cycle, purpose, and benefit component, which is the fifth, namely it is the income generated by cattle production at the household and national level. Today, an estimated (15%) fifteen percent of total beef and (17%)  seventeen percent of total milk production are exported, with a few countries only (Australia, Brazil, India, and the USA) generating substantial revenues, accounting for (10 to 12%) ten to twelve percent of world export each.  

In parallel, least developed countries find themselves increasingly dependent on imports of cattle products: the share of imports in consumption increased from (1%) one percent in 1960 to over (8%) eight percent in 2010, and in 2011, least developed countries were net importers of 90 thousand tons of beef (FAOSTAT, 2015). These factors will vary locally in a multitude of combinations. On a general level, it can nevertheless be summarized that cattle play a dominant role in food security among pastoral systems, a significant source of food and income. Furthermore, livestock products are accessible and marketable at any time, allowing to buffer against a crisis. In mixed systems, cattle contribute directly to food security by converting forages and agro-industrial by-products such as cereal brans and cakes into nutritious food. They also contribute to agriculture productivity by supplying draft power and manure. In contrast, cattle in feedlots make a limited contribution to food security and rural livelihoods (Wilkinson, 2011). Part of the feed they ingest could directly serve as food or has been cropped on areas where food could have been produced. Furthermore, the efficiency with which high-quality feed is converted into animal products is lower than for monogastric. 

Conclusion 

Beyond the methane, which is naturally emitted by all ruminants, there are levers for action on which breeders are working to reduce greenhouse gas emissions from livestock and, more generally, to improve their impact on the environment. Farmers are working to reduce their consumption of electricity and fuel oil by adjusting their tractors or insulating buildings. But energy savings also involve saving on everything that is bought outside (fertilizers, animal feed, etc.) and that requires energy to be produced: 

• • Farmers use animal droppings as natural fertilizer: spread on crops at the right dose and at the right time to preserve water quality, this recycling saves mineral fertilizers and greenhouse gases. 
  • Limited use of phytosanitary products: the vital place of meadows in most herbivore farms (60% sixty percent of their surface on average) allows them to have a balanced agronomic system with long rotations. This leads to truly little use of plant protection products. 
  • Renewable energy production: solar panels, vegetable oil as fuel, use of hedgerow wood as fuel, production of biogas thanks to the mechanization of excrement. 

Farmers maintain the meadows and hedgerows which store carbon and which in addition provide many environmental services (biodiversity, fight against erosion, preservation of water quality, landscape). In the following E-letter, we will present you with different paths that have been successful in illustrating the positive solutions when speaking of the environment and economic challenges that beef production is facing.  

We want to proceed further, more in-depth on this controversial subject. Therefore, please follow us on social media and join us on the (15^th) fifteenth of the month for Part (2!) two to learn more about the environmental impact of beef production. Thereafter, please 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.