Management Strategies for Sustainable Cattle Production in Southern Pastures

Management Strategies for Sustainable Cattle Production in Southern Pastures is a practical resource for scientists, students, and stakeholders who want to understand the relationships between soil-plant interactions and pasture management strategies, and the resultant performance of cow-calf and stocker cattle. This book illustrates the importance of matching cattle breed types and plant hardiness zones to optimize cattle production from forages and pastures. It explains the biologic and economic implications of grazing management decisions made to improve sustainability of pastures and cattle production while being compliant with present and future environmental concerns and cattle welfare programs.

• Documents the effects of cattle grazing on greenhouse gas emissions and carbon footprints
• Discusses strategies to enhance soil fertility, soil health, and nutrient cycling in pastures
• Provides information on the use of stocking rates, stocking strategies and grazing systems to optimize cow-calf production of weaned calves and stockers.
• Presents innovations in cattle supplementation and watering systems to minimize negative impacts on water and soil health
• Includes methods for weed control to maintain pasture condition and ecosystem stability
• Describes management strategies to integrate cattle operations with wildlife sustainability

• Language: English
• Publisher: Academic Press
• Release date: Aug 22, 2019
• ISBN: 9780128144756

Book preview

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Chapter 1

Introduction: Management strategies for sustainable cattle production in Southern Pastures

Monte Rouquette Jr.¹ and Glen E. Aiken²,    ¹Regents Fellow and Professor of Forage Physiology, Texas A&M AgriLife Research Center – Overton, Overton, TX, United States,    ²Center Director, UF-IFAS North Florida Research and Education Center – Quincy, Quincy, FL, United States

Abstract

Sustainable pasture–cattle production systems integrate responsible management, environmental principles and stewardship of property, and economic awareness and viability. Management strategies are uniquely linked with forage production and nutritive value, stocking rates, stocking methods, and opportunities to match forages with animal requirements for production. Southern Pastures includes a core of 13 states with 6 bordering states within the Interstate Corridors of I-10, I-20, I-30, I-40, and I-64. About 59% of the US beef cows are located in these states and most of the calves are shipped to western states for feedlot finishing.

Keywords

Management strategies; sustainable systems; beef cattle; southern states; hardiness zones; forages; pastures; Interstate Corridors

Sustainability of forages and cattle production

Management strategies provide guidance and set expectations and objectives for the overall property–pasture–cattle production goals. Sustainable beef has been defined by the Global Roundtable for Sustainable Beef (GRSB) [1] to be a product that is socially responsible, environmentally sound, and economically viable. The GRSB also emphasized that beef production should be attentive to natural resources, efficiency and innovation, people and the community, animal health and welfare, and end product to generate income. As pointed out by Rouquette [2], the natural resource principles of the GRSB serve as the primary factors of sustainable pasture–livestock systems. These natural resource principles encourage management to (1) practice environmental stewardship with adaptive management; (2) adopt practices to improve air quality and minimize net greenhouse gas emissions; (3) protect grasslands, native ecosystems, and valuable conservation areas from land conversion and degradation; (4) implement land management practices that conserve and enhance ecosystem health; (5) incorporate efficient management practices to maintain or improve soil health; (6) enhance native plants and animal biological diversity; and (7) implement management practices for sustainable-product feed sources.

Management strategies that integrate the socially responsible management, environmentally sound principles, and economically viable components of sustainability of forage–pasture–cattle production are shown in Fig. 1.1 [2]. Within a specific vegetation zone, pasture ecosystem, management inputs, and stocking strategies are the principal factors that influence sustainability of pastures and livestock production. The level or extent of aggressiveness, intensity, or stocking rate–animal performance goals of the operation are manager or ownership specific. Beef production and the value of product are controlled by biological and economic risk, and the stewardship–property legacy objectives. The economic effect and viability of the pasture–beef system are influenced by production per animal and per unit land area. These aspects of pasture management and cattle production are influenced primarily by stocking rate and secondarily by stocking method. Various stocking strategies will be discussed in the following chapters to implement forage–pasture utilization approaches that seek to optimize animal gains without destruction of the forage resource.

Figure 1.1 Sustainability of pasture–cattle production systems guided by environment, management, and economic considerations. Adapted from F.M. Rouquette, Jr., Management strategies for intensive, sustainable cow-calf production systems in the southeastern United States: Bermudagrass pastures overseeded with cool-season annual grasses and legumes, Prof. Anim. Sci. 33 (2017) 297–309. https://doi.org/10.15232/pas.2016-01591.

Stocking strategies

The assessment and identification of forage and cattle production constraints related to climatic conditions, soil fertility, ecosystem diversity, and persistent-adapted forages set the general boundaries for management inputs and output opportunities. Components of stocking strategies are the primary factors that affect the decisions for management (Fig. 1.2) [3]. The primary factors controlling a viable, sustainable operation involves selecting and utilizing adapted forage species for a specific zip code location within a vegetational hardiness zone. Management strategies that have the greatest opportunities to meet personal goals, sustainable production objectives, and economic rewards are based on comparative facts and data for forage production and utilization. Successful managers should be familiar with cause–effect relationships of pasture–animal performance, and the short-term, seasonal, and yearlong climatic conditions related to rainfall and temperature. Thus, within a specific vegetational zone, managers must combine on-site, visual assessment, and management of efficient, sustainable forage use for desired pasture–animal production. Management must be aware of the competitive challenges of climatic conditions and the current and strategic rainfall–temperature related issues. Using appropriate inputs (Fig. 1.2), managers can make decisions and stocking strategies that stimulate forage production, utilization, and nutritive value for desired animal performance. Some of the most valuable factors to consider to optimize system outputs include: (1) an understanding and expectation of forage growth and regrowth; (2) experience with animals and animal husbandry; (3) the ability to assume biological and economic risks associated with stocking outcomes; (4) a constant awareness of vegetation, land, and water resources; (5) an alternative or escape plan for animals and pastures in the event of extreme climatic conditions; and (6) an intuitive application of decisions for inputs and output [3].

Figure 1.2 Inputs and outputs of forage–animal production systems as affected and directed by stocking strategy decisions. Adapted from F.M. Rouquette, Jr., Grazing systems research and impact of stocking strategies on pasture-animal production efficiencies, Crop Sci. 55 (2015) 2513–2530. https://doi.org/10.2135/cropsci2015.01.0062.

Stocking strategies are uniquely linked and integrated with decisions on forage production, grazing pressure, stocking rates, stocking methods, deferment of pastures, and mechanically harvested forages. A stocking strategy is a daily and seasonal approach to forage utilization using stocking rates and stocking methods [3]. Changes in stocking rates and deferment may be made according to various classes, age, and weight of livestock to achieve the primary objectives of optimum forage use for desired optimum or maximum animal performance [3]. Stocking strategies and management decisions used to optimize forage utilization and animal performance lead managers to incorporate the concept of flexible grazing management [4]. Blaser et al. [5] introduced the use of flexible grazing systems by adjusting stocking methods and forage utilization strategies on visual–quantity bases and not a calendar-basis to optimize gain per animal and/or gain per acre.

Plant Hardiness Zones and Southern Pastures

The Southern Pasture areas that are discussed throughout the following chapters are the same states and general locations shown and discussed in Southern Forages [6]. This overall southern region comprises the core states that were part of the original 13 member states of the Southern Pasture and Forage Crop Improvement Association that was founded in 1940 at Tifton, GA [7]. These 13 states include Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia. These states are included in one or more of six of the USDA Plant Hardiness Zones (Figs. 1.3 and 1.4) [8]. These Southern Pastures are bounded on the west by Texas and Oklahoma, and include all those states bordering the Gulf of Mexico. This geographical area includes the Atlantic seaboard states of Georgia, South Carolina, North Carolina, and Virginia, and the land-locked states of Arkansas, Tennessee, and Kentucky. Management strategies will be presented within the Hardiness Zones and subdivided as follows: (1) Lower South: Interstate 10 Corridor; (2) Middle South: Interstate 20 Corridor; and (3) The Upper South: Interstate 30, Interstate 40, and Interstate 64 Corridors. The forage base of the Lower and Middle South is primarily warm-season perennial grasses such as bermudagrass and bahiagrass (Fig. 1.5) [9,10]. The primary pastures in the Upper South include cool-season perennial grasses such as tall fescue with some mixed bermudagrass pastures (Fig. 1.6) [11]. In all Hardiness Zones, cool-season annual grasses and legumes may be used to extend the active forage growing and grazing season for 300–365 days [12]. These annual forages provide the greatest nutritive value of any class of forages, and are important for reproduction and animal gain. The success of seasonal or yearlong pastures and grazing systems are dependent on adapted forages to the zip code-specific Hardiness Zones. Management strategies that promote and stabilize sustainable pastures can be implemented. Management success is challenged by climatic conditions and soil fertility that affects monthly, seasonal, and total forage production. By integrating these controlling factors, decisions can be made for pasture utilization strategies. Stocking rate and flexible rotation adjustments among pastures can fulfill utilization strategies for desired animal performance and economic rewards. Adjustments in stocking rates and utilization strategies may involve harvested forage as hay or baleage from pastures.

Figure 1.3 Extreme minimum temperatures and average first-last freeze dates in southern region. Adapted from USDA/ARS, Plant Hardiness Zones. <http://planthardiness.ars.usda.gov>, 1990 (accessed 07.03.18).

Figure 1.4 A 30-year average annual precipitation in the southern region, 1981–2010. Adapted from USDA/ARS, Plant Hardiness Zones. <http://planthardiness.ars.usda.gov>, 1990 (accessed 07.03.18).

Figure 1.5 Warm-season perennial grasses, bermudagrass and bahiagrass, adaptation area in the southern region. Adapted from G.W. Burton, W.W. Hanna, Bermudagrass, in: M.E. Heath, R.F. Barnes, D.S. Metcalfe (Eds.), Forages: The Science of Grassland Agriculture, fourth ed., Iowa State Univ. Press, 1985, pp. 247–254; V.H. Watson, B.L. Burson, Bahiagrass, carpetgrass, and dallisgrass, in: M.E. Heath, R.F. Barnes, D.S. Metcalfe (Eds.), Forages: The Science of Grassland Agriculture, fourth ed., Iowa State Univ. Press, 1985, pp. 255–262.

Figure 1.6 Primary use area for tall fescue in the southern region. Adapted from R.C. Buckner, The fescues, in: M.E. Heath, R.F. Barnes, D.S. Metcalfe (Eds.), Forages: The Science of Grassland Agriculture, fourth ed., Iowa State Univ. Press, 1985, pp. 233–240.

The 13 core states are home to about 44% (13.6 M) of the beef cows in the United States [13]. There are six other states that adjoin the Upper South and are located in the Fescue Belt. These states include Kansas, Missouri, Illinois, Indiana, Ohio, and West Virginia, and are in similar Hardiness Zones to those states of the Interstate 64 Corridor. By combining these 6 states and the core 13 states, there are about 59% (18.6 M) of the US beef cows located in this southern and eastern region [13]. Thus, management strategies of sustainable pasture–cattle production on Southern Pastures have a major effect on the total US cow numbers, total calves weaned, weight of cattle entering feedlot, and overall beef quality.

Beef cattle production practices on Southern Pastures

As a component of the US Beef Sustainability Program, a characterization of regional beef production practices was conducted for the northeast and southeast United States. Information obtained by surveys and on-site visits suggested that 80% of the producers maintained less than 100 cows. The characterization of the cow-calf industry in the southeastern United States showed that about 60% of operations were cow-calf only, and 23% were both cow-calf and stocker [14]. In another overview [15] it was reported that 70% of the operations weaned calves at 6–8 months of age; 68% sold all calves at weaning except for replacements; 23% retained calves for preconditioning prior to sales; about 10% retained calves through the stocker phase; about 75% of operations sold calves at local auctions; and about 15% were stocker only operations.

Breed types of cows in the I-10 Corridor are predominately Bos indicus purebred and crossbred with Bos taurus. The preferences for the Brahman-influenced cows have been well-established with longevity, persistence, adaptation to the environment–climatic conditions, and overall productivity with respect to percent weaning and weaning weights. In the I-20 Corridor, both Brahman-influenced breed types and non-Brahman cows are the primary breed types used. In the Upper South, the predominant breed types of cows are non-Brahman and include both English and Continental sires. In the 2008 survey [14] Angus cattle were reported as the dominant breed type on about 70% of the operations, and Hereford cattle were the next preferred breed type.

Results of the US Beef Sustainability survey [14] showed that operators used a bull for 21 cows, had an average stocking rate of about one cow-calf pair per 2.5–3.0 acres, and stocking rates ranged from 1 to 20 acres per pair. From the pasture fertility perspective, 65% used nitrogen fertilizer at about 100 lbs/acre; 45% used phosphate (P2O5) at about 70 lbs/acre; 50% used potash (K2O) at about 70 lbs/acre; and nearly 80% applied limestone to buffer soil pH. These survey data revealed that about 65% of the operators harvested pasture for conserved forage, and primarily as hay. Cattle born in the southeastern United States are most often shipped to feedlots and finished in Western Regions that are closer to feed grain (corn) sources.

Management questions for sustainability

Input information that managers need may arise from some of the following questions: (1) What forage(s) do I have, and which forages are best adapted to my property? (2) What is the level of soil fertility in pastures, and fertilizer required for desired forage production? (3) What is the best stocking rate for my operation, and what visual or measured indicators show an optimum stocking rate strategy for sustainable cattle production? (4) Should I produce or purchase hay, and how do I know if a supplemental protein or energy may be needed? (5) What breed types of cattle are best adapted to my vegetational zone, and what season(s) should they calve? and (6) How do I plan my forage–cattle operational system which includes a sustainable ecosystem that encourages wildlife food and habitat? These and many more questions may be asked by both the novice landowner and experienced manager. The management strategies addressed in the following chapters have been structured to provide detailed information on soil–forage–animal–environment relationships for management successes.

References

1. GRSB, Global Roundtable for Sustainable Beef. <https://www.grsbeef.org/what-sustainable-beef/naturalresources>, 2016 (accessed 01.09.18).

2. Rouquette Jr FM. Management strategies for intensive, sustainable cow-calf production systems in the southeastern United States: Bermudagrass pastures overseeded with cool-season annual grasses and legumes. Prof Anim Sci. 2017;33:297–309 https://doi.org/10.15232/pas.2016-01591.

3. Rouquette Jr FM. Grazing systems research and impact of stocking strategies on pasture-animal production efficiencies. Crop Sci. 2015;55:2513–2530 https://doi.org/10.2135/cropsci2015.01.0062.

4. Burns JC. Grazing research in the humid east: a historical perspective. Crop Sci. 2006;46:118–130 https://doi.org/10.2135/crop-sci2005.0185.

5. Blaser RE, Harlan JR, Love RM. Grazing management. In: Mott GO, ed. Pasture and Range Research Techniques. Ithaca, NY: Comstock Publ. Cornell Univ. Press; 1962;11–17.

6. Ball DM, Hoveland CS, Lacefield GD. Southern Forages: Modern Concepts for Forage Crop Management fifth ed. Atlanta, GA: International Plant Nutrition Institute; 2015.

7. Southern Pasture and Forage Crop Improvement. <https://archive.org/details/usda-soutilpasfor/1940>. (accessed 07.03.18).

8. USDA/ARS, Plant Hardiness Zones. <http://planthardiness.ars.usda.gov>, 1990 (accessed 07.03.18).

9. Burton GW, Hanna WW. Bermudagrass. In: Heath ME, Barnes RF, Metcalfe DS, eds. Forages: The Science of Grassland Agriculture. fourth ed. Iowa State Univ. Press 1985;247–254.

10. Watson VH, Burson BL. Bahiagrass, carpetgrass, and dallisgrass. In: Heath ME, Barnes RF, Metcalfe DS, eds. Forages: The Science of Grassland Agriculture. fourth ed. Iowa State Univ. Press 1985;255–262.

11. Buckner RC. The fescues. In: Heath ME, Barnes RF, Metcalfe DS, eds. Forages: The Science of Grassland Agriculture. fourth ed. Iowa State Univ. Press 1985;233–240.

12. Mullenix MK, Rouquette Jr FM. Cool-season annual grasses or grass-clover management options for extending the fall-winter-early spring grazing season for beef cattle. Prof Anim Sci. 2018;34:231–239 https://doi.org/10.15232/pas.2017-01714.

13. USDA-NASS, National Agricultural Statistics Service, Cattle. <http://usda.mannlib.cornell.edu/usda/nass/catt/2010/2017/catt-01-31-2017.pdf>, 2017 (accessed 07.03.18).

14. Senorpe Asem-Hiablie C, Rotz A, Stout R, Pace S. Management characteristics of beef cattle production in the eastern United States. Prof Anim Sci. 2018;34:311–325 https://doi.org/10.15232/pas.2018-07128.

15. J.P. Banta, J.M. Hersom, J.W. Lehmkuhler, J.D. Rhinehart, L. Stewart, Symposium: An Overview of Cow-Calf Production in the Southeast: Forage systems, Cow Numbers, and Calf Marketing Strategies, ASAS So. Sect. Abst. 2016.

Chapter 2

Cattle grazing effects on the environment: Greenhouse gas emissions and carbon footprint

Alan J. Franzluebbers,    USDA-Agricultural Research Service, Raleigh, NC, United States

Abstract

Perennial pastures are an important component of beef cattle production for cow–calf operations in the Southeastern United States. Greenhouse gas emissions are dominated by enteric methane (CH4), accounting for ~60% of total emissions from beef production. With significant N fertilization of pastures, nitrous oxide (N2O) emission is often the second most important greenhouse gas, accounting for ~30% of total emissions from beef production. Region-specific data on greenhouse gas emissions from beef production are lacking, and yet these data are essential to design Southern pastures for improved resource efficiency. Forages with high nutritive value can reduce CH4 emissions by grazing cattle, as a consequence of greater feed efficiency and shorter time to gain maturity. In addition, forages with significant tannins, saponins, and other biochemical components may have the potential to mitigate against enteric CH4 emission. Nitrogen fertilization of pastures often leads to greater soil N2O emission. Establishing and maintaining legumes in pastures can limit the need for external N inputs. Forage production systems that rely on farm-derived nutrients (e.g., precision litter decomposition with management-intensive grazing, application of additional manure sources, and composts), keeping brood cows healthy and productive, and getting calves to finishing weight faster are keys to reducing greenhouse gas emissions from Southern pastures. Also, significant soil organic C sequestration should be a focus to reduce the overall C footprint of animal agriculture in the region.

Keywords

Carbon dioxide; enteric emission; greenhouse gas; manure; methane; nitrous oxide; soil organic carbon

Introduction

The Southeastern United States is characterized by relatively warm and wet conditions. Variations occur throughout the region and from year to year, but in general, precipitation is abundant throughout the year and temperature is hot in the summer and mild in the winter (Fig. 2.1). Such environmental conditions are important features that affect soil and water resources, which together ultimately affect agricultural production and environmental quality characteristics of the region.

Figure 2.1 Climate characteristics of locations in the Southeastern United States. P, precipitation (inches); T, temperature (°F); PET, potential evapotranspiration (in.).

Soils in the Southeastern United States are generally characterized as relatively poor in fertility due to a low level of base cations, low pH, low organic matter, and coarse texture. According to USDA Natural Resources Conservation Service, the Southeastern United States is categorized into land resource regions defined by soil and landscape features along with historical management. Regions include (N) east and central farming and forest region; (O) Mississippi delta cotton and feed grains region; (P) south Atlantic and gulf slope cash crops, forest, and livestock region; (T) Atlantic and gulf coast lowland forest and crop region; and (U) Florida subtropical fruit, truck crop, and range region [1]. Major land resource areas are more specific categorization that separates unique soil and landscape characteristics. Soil orders in the region include:

• Ultisols—Highly weathered soils that have been leached of cations, such as calcium and magnesium, and are acidic.

• Alfisols—Moderately weathered soils, slightly acidic, and having enriched clay content below the surface.

• Inceptisols—Moderate degree of soil development and lacking clay accumulation in the subsoil.

• Entisols—Little to no soil development typically in flood plains and sand dunes.

• Mollisols—Deep, fertile, dark-colored surface rich in base cations.

• Histisols—Highly enriched organic soils from historical water submersion.

Differences in soil types are likely to have impacts on site-specific greenhouse gas emissions, particularly with regard to soil organic carbon (C) sequestration potential and soil nitrous oxide (N2O) emissions. Enteric methane (CH4) emissions in the region are not likely to be vastly different than in other regions if ruminants are fed a similar diet in confinement but could be different when raised on pasture forages. The botanical composition may affect intake and nutritive value, as well as the timing of grazing with respect to environmental conditions, all of which could affect rumen microbiota. Secondary metabolites in various forages may alter rumen microbiota as well.

The Southeastern United States is mostly an undulating landscape with significant forestlands, but also contains important corridors of rapidly expanding human population and associated transportation and industrial developments. These features are important to characterize the relatively small and variable nature of pastures throughout the region. Fig. 2.2 is an example of landscape cross-sections to show broad undulations in landscape across the Appalachian Mountains, Piedmont, and Coastal Plain regions.

Figure 2.2 Cross-section maps every 100 miles across the Southeastern United States at ~35°N latitude. Value at left in each panel indicates the number of times a 100′ elevation isoline is intersected in each image.

Carbon cycle and greenhouse gas emissions

The global C cycle can be partitioned into five major pools based on quantity of C stored (Pg=10¹⁵ g; 984 million English tons): oceanic (38,000 Pg), geologic (5000 Pg), pedologic (2500 Pg; composed of 1550 Pg in organic form and 950 Pg in carbonate form), atmospheric (760 Pg), and biotic (560 Pg) [2]. Soil organic C contains, therefore, 2–3 times the C as biotic and atmospheric pools. Soil organic C is the dominant storage pool in cropland and grasslands.

The terrestrial C cycle is dominated by two important fluxes: photosynthesis (net ecosystem uptake of carbon dioxide from the atmosphere) and respiration (release of C back to the atmosphere via plant, animal, and soil microbial respiration). Biochemical transformations occur at numerous stages in the C cycle, for example, simple sugars in plants are converted into complex C-containing compounds, animals consuming plants create bioactive proteins, and exposure of plant and animal residues to soil microorganisms and various environmental conditions creates humified soil organic matter complexes. Human intervention often results in the harvest of enormous quantities of C as food, fiber, fodder, and energy products. Additionally, unintended consequences of management can result in significant erosion of soil and leaching of nutrients.

Although carbon dioxide (CO2) is the dominant greenhouse gas (due to its relatively high concentration in the atmosphere and magnitude of additional CO2 being emitted to the atmosphere from land-use change and burning of fossil fuels), agriculture also emits two other important greenhouse gases, CH4 and N2O. Each of these three greenhouse gases has significant relevance for pasture-based livestock production systems in the Southeastern United States. In the United States, CO2 in agriculture is accounted primarily as land-use change through its impact on soil organic C. Fossil fuels consumed in operating agricultural equipment are typically accounted in the energy and transportation sectors. Significant CO2 sequestration (i.e., negative emissions) can occur as a result of plant uptake (i.e., photosynthesis) and storage of dead biomass in the soil as organic C. Ruminant livestock production is a very important contributor to CH4 emissions. Agricultural soils (both croplands and grazing lands) are important contributors to N2O emissions. All three greenhouse gases have been increasing during the past century, as a result of greater production and reliance on mechanization in agriculture (Fig. 2.3). As a sector, agriculture accounts for ~9% of all greenhouse gas emissions in the United States (Fig. 2.4).

Figure 2.3 Atmospheric concentrations over time of three greenhouse gases of relevance in agriculture: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) [3].

Figure 2.4 Sectoral contributions to total greenhouse gas emissions in the United States [4].

Sources of greenhouse gas emissions are often combined in calculations of C footprint or global warming potential in terms of CO2 equivalence. These equivalencies are based on the reactivity of each gas over a specified time, most often during a 100-year period. Carbon dioxide is considered the reference gas because it is the most abundant greenhouse gas and has the lowest reactivity. One unit of CH4 is equivalent to 25 units of CO2. One unit of N2O is equivalent to 298 units of CO2 [5]. In the United States, agricultural greenhouse gas emissions of relative importance and their sources of emission are shown in Fig. 2.5.

Figure 2.5 Sources of greenhouse gas emissions in US agriculture [4]. Note: 1 MMT CO2 Eq.=0.27 million English tons of CO2-C equivalence.

Enteric methane emission

Globally, CH4 emission contributes about 20% of the estimated human-induced greenhouse gas emissions, second behind CO2 emission at 60% [6]. In 2011, the atmospheric concentration of CH4 was 1803 ppb (parts per billion) [7], which was more than double the concentration of ~700 ppb in 1700 AD [8]. Global sources of CH4 emission are livestock production, rice farming, waste decomposition (animal waste, crop residues, and landfills), and fossil fuel mining. Livestock sources of CH4 emission (enteric and manure) account for 20%–34% of all global emissions of CH4 [9,10] (Fig. 2.6).

Figure 2.6 Components of the life-cycle assessment for beef production in southern Alberta. From K.A. Beauchemin, H.H. Janzen, S.M. Little, T. McAllister, S.M. McGinn, Life cycle assessment of greenhouse gas emissions from beef production in western Canada: a case study, Agric. Syst. 103 (2010)