Over the last several decades, animal agriculture in the United States—including dairy, poultry, pork, and beef—has made tremendous strides in production efficiency, as described in the previous chapter. Whether this will continue is now in question. Between 1982 and 2007, more than 41 million acres of rural land (crop, pasture, range, land formerly enrolled in the Conservation Reserve Program, forest, and other rural land) in the United States has been converted to developed uses (Farmland Information Center, 2014). This represents the size of the combined areas of Illinois and New Jersey, or more than half the land that is annually planted to soybeans in the United States. If this trend of ever-increasing amounts of land taken out of rural use continues, then production efficiency and yields must increase at an even greater level to maintain the current level of food production, not to mention the future animal product consumption demands of the increasing American population (Box 3-1). These need to be increased in the face of global challenges such as climate change, increased regulations, and various public and social concerns regarding animal welfare and the use of technologies that have contributed and could contribute to production efficiency.
This chapter covers key issues for animal sciences research considerations for the United States. It provides a summary of reports by various policy and other stakeholder groups engaged in animal science research across various disciplines, and then discusses topics on the importance of the research contributions of animal sciences research to
productivity, trade, funding, sustainable food security, the environment, and socioeconomic considerations. The role of animal agriculture research in U.S. welfare is described in terms of food security and food safety, health, jobs, and trade. There is also a discussion of challenges to U.S. animal agriculture, including social concerns, increasing regulations, the environment, and a decreasing agricultural land base to produce not only the same amount of food as presently produced but to also meet the increasing demand for global animal protein by the year 2050.
In keeping with its charge, the committee has focused its efforts on animal agricultural research; however, the broader context of overall agricultural R&D, for which there is more information available, provides additional reason for concern. Kennedy (2014), in a recent editorial in Science, describes the agricultural research sector as suffering from decades of neglect which must be reversed if we are to sustain a population of 9 billion people. Heisey et al. (2011) evaluated the impact of future public agricultural research spending scenarios on overall U.S. agriculture productivity growth from 2010 to 2050. A 50 percent fall in the rate of increase in U.S. agricultural productivity is predicted if agricultural funding increases continue unchanged at the current rate, which is less than the expected rate of inflation of research costs. In contrast, funding that meets the rate of research cost inflation leads to a 73 percent increase in productivity between now and 2050—and a 1 percent increase in inflation-adjusted spending is projected to lead to an 83 percent increase (Heisey et al., 2011).
Data specific to animal agricultural research are harder to find. The committee, however, believes that animal agricultural research has borne the brunt of the decades of neglect described by Kennedy (2014), particularly in private funding. Globally, private food and agricultural R&D for crops has increased 53 percent from $5,697 million in 1994 to $8,711 million in 2010, while the total for animal R&D only increased 4 percent (from $1,516 million to $1,577 million). Of note is that Fuglie et al. (2011) also reported that the relative amount of private animal as compared to crop research in 2006 was lower in the United States ($432 million animal vs. $2,392 million crops; 18 percent less) than in the rest of the world ($1,033 animal vs. $4,133 million crops; 25% less). Heisey of the U.S. Department of Agriculture (USDA) found that public funding in the United States for crop and animal research have both grown only marginally over the period 1999-2007 (K. Fuglie, USDA, personal communication, November 6, 2014).
Animal Protein Availability in the United States
The U.S. Department of Agriculture’s Economic Research Service tracks per capita food availability as a proxy for food consumption. The data show that beef availability grew substantially starting in the 1960s, reaching a peak of 88.8 pounds per capita per year in 1976. Since that time, beef availability has declined to roughly the same level as in 1909 when recordkeeping began. In contrast, chicken availability exploded in the second half of the 20th century. In 2012, 56.6 pounds of chicken were available per person per year, over 2 pounds more than beef. Pork production has fluctuated much less than beef or chicken. Fish and shellfish availability was 30 percent higher in 2012 than in 1909, but was still a relatively small portion of available animal protein compared with beef, chicken, and pork (Figure 3-1). Animal protein available from eggs and dairy products has fallen on a per capita basis, even though the supply of eggs has remained relatively constant since the 1960s and the dairy supply has more than doubled since the 1920s (Figures 3-2 and 3-3).
FIGURE 3-1 Beef, pork, chicken, and fish and shellfish from 1909 to 2012.
SOURCE: USDA ERS (2014).
FIGURE 3-2 Number of eggs available from 1966 to 2012.
SOURCE: USDA ERS (2014)
FIGURE 3-3 Dairy product availability from 1909 to 2012.
SOURCE: USDA ERS (2014).
3-1 Animal Science Research Needs
There have been multiple reports over the past decade that summarized the needs and future strategies for animal agriculture research. The USDA’s Research, Education, and Economics (REE) has identified 15 key strategies for animal agriculture (USDA REE, 2012), which are included in Appendix D. In brief, these strategies focus on research related to genomics, new varieties and germplasms, sustainability of animal production and the environment, animal disease control, climate impacts, reduction of foodborne contaminants, effective management strategies, and development of animal sciences workforces. The USDA Agricultural Research Service (ARS) has proposed five main areas as FY 2015 research priorities (Appendix E), including (in ranking of budget investment) food safety, food animal protection and production, climate change, and genetic improvement and translational breeding. A stakeholder meeting sponsored by USDA ARS developed a prioritized list of research topics by species and disciplines (Appendix F).
In the 2012 Farm Animal Integrated Research (FAIR) report (Box 3-2; FASS, 2012), a collaboration of scientists, educators, producers, industry representatives, health professionals, and government representatives emphasize six crosscutting issues. These included fundamental and applied research in animal sciences, a balance of projects including large multi-institution grants and small grants, enhanced collaborations among universities and government agencies, increased public awareness of animal agricultural research, improved communication of animal science to policy makers, and an established data-mining system.1
A separate study (Rouquette et al., 2009) compiled recommendations from scientists at 25 land grant universities for future forage utilization research needs. Among the highest-priority needs were research on pasture systems and production efficiency, energy concerns, evaluation
1 As research priorities are set and agendas are developed, it is important that comprehensive mining of historical data be conducted, to understand what is already known, to prevent unnecessary duplication, and to provide a better base on which to build future research. Data mining will reveal information that can be converted into knowledge about historical research, and these data can be used to predict future trends to be applied in research planning to support guidelines and policies (FASS, 2012).
of forage cultivars, environmental impacts, and soil fertility and nutrient management.
FAIR 2012 Report
Scientists, educators, producers, industry, health professionals, and government representatives gathered together in 2012 under the Farm Animal Integrated Research 2012 (FAIR, 2012) initiative to identify research, extension, and education priorities that will enable animal sciences to meet the key future animal agricultural challenges. Three major themes (Food Security, One Health, and Stewardship) emerged for further investment. Within Food Security, feed efficiency, energetic efficiency, and connecting “omics” to animal production and reproduction were highlighted as key research areas. The following areas were highlighted within the One Health area: new approaches to vaccine development, understanding and controlling zoonoses with an emphasis on food safety, and improving animal health through feed. Under Stewardship, the following research areas emerged: flow of nutrients and other potential pollutants from animal production systems, estimation and reduction of greenhouse gas production, and impacts of housing systems on animal well-being. FAIR 2012 emphasized six crosscutting issues:
- Balanced portfolio where support for research spans from fundamental to applied, support for extension to help enhance adoption of the new technologies, and support for education to ensure a robust pipeline to develop new scientists, producers, and industry professionals;
- Balanced size and scope of projects from large, multiinstitutional grants to small grants;
- Enhanced collaborations among universities, USDA, National Institutes of Health, National Science Foundation, Department of Energy, and others to leverage resources and stimulate innovation;
- Increased public awareness through informing the consumer of the benefits and value of animal agricultural production and research;
- Improved communication of science to policy makers such that a consistent and predictable regulatory process based on sound science is instituted; and
- Establishment of a data-mining system.
For aquaculture research, the National Oceanic and Atmospheric Administration (NOAA) and the USDA have developed nine critical strategic goals in their 2014 National Strategic Plan for Federal Aquaculture Research (Box 3-3). These include research goals related to improving production efficiency and performance, animal well-being and nutrition, biosecurity and disease control, and the safety and nutrition of seafood for humans; developing a skilled workforce and socioeconomic and business strategies for aquaculture; and enhancing use of genetics to increase productivity and understanding of aquaculture–environment interactions.
Additionally, NOAA identified four goals for the year 2025 to expand U.S. marine aquaculture, including a comprehensive regulatory program for environmentally stable aquaculture, developing commercial aquaculture and replenishment of wild stocks, improving public understanding of aquaculture, and increased collaboration with international partners. Relevant to sustainability, Hume et al. (2011)
National Strategic Plan for Federal Aquaculture Research (2014)
This plan was developed by the Interagency Working Group in Aquaculture (IWG-A) and includes nine critical strategic goals with outcomes and milestones. The strategic goals are:
- Advance understanding of the interactions of aquaculture and the environment;
- Employ genetics to increase productivity and protect natural populations;
- Counter disease in aquatic organisms and improve biosecurity;
- Improve production efficiency and well-being;
- Improve nutrition and develop novel feeds;
- Increase supply of nutritious, safe, high-quality seafood and aquatic products;
- Improve performance of production systems;
- Create a skilled workforce and enhance technology transfer; and
- Develop and use socioeconomic and business research to advance domestic aquaculture.
SOURCE: NSTC (2014).
identified three objectives for animal production systems: (1) maximizing the number of productive offspring per breeding male and female, (2) maximizing efficiency of converting feed and water to useful animal product, and (3) minimizing waste and losses through infectious and metabolic diseases.
As evidenced by the content of these reports, various stakeholders in the United States—from government agencies to industries to academics to producers—recognize the importance of animal sciences research as the means to ensure a safe, high-quality, plentiful, and affordable food supply to meet the future protein demand in the United States and the world. Common themes arise across these multiple reports, including climate change concerns; continued development and use of emerging technologies to improve animal production efficiency, animal health, and feed and food safety and quality; animal waste management; development of underutilized resources; and ensuring appropriate infrastructure and collaborations to achieve sufficient animal production in the future. Despite these common themes, USDA ARS only allocated 16 percent ($176 million) of its proposed FY 2015 budget to animal production research and 8 percent to product-quality/value-added research compared to 36 percent for crop research, 18 percent for food safety and nutrition, and 18 percent for environmental stewardship (Appendix J). The National Institute of Food and Agriculture (NIFA) allocated $103 million to animal science research in its FY 2012 budget. This is less than 1 percent of the value that animal products contribute to the U.S. economy. Animal agriculture annually accounts for between 60 and 70 percent of the total agriculture economy (often exceeding $100 billion/year) and plays an important role in the balance of agricultural trade (USDA ERS, 2013). Exports of pork, lamb, broiler, and dairy products equal $6 billion, $26 million, $4.2 billion, and $6.7 billion annually, respectively (USMEF, 2012a,b; Davis et al., 2013; U.S. Dairy Export Council, 2014). This chapter further describes the historical, current, and future technologies that improve animal sciences production, efficiency, sustainability, and safety in the United States. Findings and recommendations are presented for future animal science to ensure a sustainable food supply in the United States, focusing on and integrating U.S. and global perspectives. The nexus of animal science research and the economic, environmental, and social pillars of sustainability are also addressed in greater detail.
While previous reports focus on disciplines and topics important to animal sciences research, there has heretofore been less emphasis on a
vision of a systems approach to research, which can incorporate the entire food production system. This is what the current report brings to bear in analysis of needs for future animal sciences research.
In view of the anticipated continuing increased demand for animal protein, growth in U.S. research related to animal agricultural productivity is imperative. Animal protein products contribute over $43 billion annually to the U.S. agricultural trade balance. Animal agriculture accounts for 60 to 70 percent of the total agricultural economy. In the past two decades, public funding, including formula funding and USDA ARS/NIFA funding, of animal science research has been stagnant in terms of real dollars and has declined in relation to the research inflation rate. A 50 percent decline in the rate of increase in U.S. agricultural productivity is predicted if overall agricultural funding increases in normative dollars continue at the current rate, which is less than the expected rate of inflation of research costs. If funding does meet the rate of research cost inflation, however, a 73 percent increase in overall agricultural productivity between now and 2050 is projected and a 1 percent increase in inflation-adjusted spending is projected to lead to an 83 percent increase.
Despite documenting the clear economic and scientific value of animal science research in the United States, funding to support the infrastructure and capacity is evidently insufficient to meet the needs for animal food; U.S.-based research will be needed to address sustainability issues and to help developing countries sustainably increase their own animal protein production and/or needs. Additionally, animal science research and practices in the United States are often adopted, to the extent possible, within developing countries. Thus, increases in U.S. funding will favorably impact animal production enterprises in developing countries.
With the lack of increase in public funding of animal science research, private/industry support has increased. The focus of industry funding is more toward applied areas that can be commercialized in the short term. Many of these applications are built on concepts developed from publicly funded basic research. With the increased animal protein demands, especially poultry, more publicly funded basic research is needed.
To meet current and future animal protein demand, and to sustain corresponding infrastructure and capacity, public support for animal science research (especially basic research) should be restored to at least past levels of real dollars and maintained at a rate that meets or exceeds the annual rate of research inflation. This is especially critical for those species (i.e., poultry) for which consumer demand is projected to significantly increase by 2050 and for those species with the greatest opportunity for reducing the environmental impact of animal agriculture.
Priorities for Research Support
USDA ARS spends 50 percent more on crop research and a greater percentage of its budget on food safety and nutrition and environmental stewardship than on animal production research. In addition, in the past couple of decades, public funding (USDA ARS/NIFA) of animal science research has been declining in terms of real dollars. One priority for research support in this area includes:
- USDA through its relevant agencies is encouraged to maintain high priority for funding for research, including translational research, that is commensurate with the future needs of livestock protein. USDA should maintain and enhance the current link to the livestock, poultry, and aquaculture industries in the United States with the aim of building better public–private partnerships in funding research in animal science.
3-2 Productivity and Production Efficiency
Productivity is a key element in achieving food security, and production efficiency relates to sustainability through its effects on economics and environmental impacts. Increasing the productivity per animal unit and land unit while concomitantly decreasing negative impacts on the environment (sustainable intensification) can ultimately produce safe, affordable, and nutritious food to help meet overall global food and protein needs. Technological advancements, genetic improvement, better nutrition, husbandry, and advances in animal health and welfare in animal production have contributed to major productivity
and efficiency gains in food animals (Table 3-1; Hume et al., 2011). The mechanization of animal agricultural production systems, such as animal waste materials disposal, milking machines, milking parlors, milking robotics, poultry houses with automatic feeding, watering, and egg collection, and feed storage systems was advanced through research activities that combined both engineering and biological disciplines. The transition from draft power to fuel power in animal feed production was achieved through similar research. The preceding examples provide evidence of the combined-discipline approaches to solving issues that are directly related to the essential requirements for more efficient food production systems. The use of technological improvements to reduce negative environmental impacts associated with animal waste is the subject of Box 3-4.
From 1977 to 2012, commercial pork production in the United States increased 174 percent from slaughtering more and larger pigs than previously marketed (Mathews et al., 2013). Public and private R&D during this period led to efficiency gains that have altered the structure of the pork industry. Some of the gains in productivity are attributable to increases in the scale of production and technological innovation. A major contributing factor is the genetic improvement of animals through research, from lard-producing pigs prior to the 1980s to leaner meat-type pigs, which is evident in improvements in meat quality and weight gain per animal. Average dressed weight of barrows and gilts (young male and female hogs, respectively) has increased 25 percent since 1977, from an annual average of 163 pounds in 1977 to 203 pounds in 2011 (Mathews et al., 2013).
Technologies to Reduce Environmental Impact of Animal Wastes Associated with Maximizing Productivity
Animals require special nutrients designed to optimize their productivity and performance. However, dietary nutrients, such as nitrogen and phosphorus, when applied in excessive quantities or in a fashion that facilitates surface runoff, can exert harmful effects on the surrounding environment. Excess nitrogen can contaminate groundwater and surface-water supplies, and decrease air quality while excessive phosphorus can build up in soil after the land application of animal manure and run off into surface waters, causing eutrophication. The addition of crystalline amino acids to the diet results in a 1 percent unit decrease in
crude protein concentration, which corresponds to a 10 percent decrease in nitrogen excretion. Adding the enzyme phytase into swine and poultry diets, which they lack naturally, can improve the digestibility of phosphorus by 20 to 50 percent. Recent research has found that the protein requirements of dairy animals can be met with lower crude protein diets without affecting milk production. A reduction in phosphorus concentration from 0.47 to 0.31 percent in the diet of dairy cattle results in a 50 percent reduction in phosphorus excretion. Reduced levels of dietary crude protein in dairy cattle and phase feeding in beef cattle have reduced nitrogen excretion. By using the knowledge of animal nutrient requirements gained from research, along with frequent feed nutrient analysis and animal performance data, a precision feeding strategy aims to optimize delivery of the level of nutrients required by the animals to reduce production costs and environmental pollution (Carter and Kim, 2013)
TABLE 3-1 Improvements in Food Animal Productivity over the Past 40 to 50 Years
|Pig||Pigs weaned per sow/year||14||21||50|
|Proportion of lean meat||0.40||0.55||37|
|Feed conversion ratio (FCR)||3.0||2.2||27|
|kg lean meat/ton feed||85||170||100|
|Chicken, broiler||Days until 2 kg are reached||100||40||60|
|Eggs/ton of feed||5,000||9,000||80|
|Dairy cow||kg milk/cow/lactation||6,000||10,000||67|
SOURCE: Modified from van der Steen et al. (2005); Hume et al. (2011).
McBride and Key (2013) reviewed U.S. pig production from 1992 to 2009 and reported that technology innovation through advances in nutrition, genetics, housing, handling equipment, veterinary services, and management improved hog performance and efficiency. Adoption of artificial insemination to improve genetic potential and conception rates increased from 7 percent in 1990 to 46 percent in 2006 (USDA National
Animal Health Monitoring Service survey data). All-in and all-out housing management is another innovative practice to enhance productivity that was increased from 25 percent in 1990 to 71 percent in 2006. Subtherapeutic antibiotics for growth promotion, disease prevention, and overall animal health improvement have been used since the 1950s. Typically, an increase in feed efficiency and productivity was observed, especially in nursery pigs. With the concern of antimicrobial resistance in the human population, the use of antimicrobials in swine production has been decreasing since 2004.
With major gains in production efficiency from utilizing these systems and practices come significant reductions in environmental impacts (Hume et al., 2011). For example, modern beef production requires considerably fewer resources than the equivalent system in 1977, with 70 percent of animals, 81 percent of feedstuffs, 88 percent of the water, and only 67 percent of the land needed to produce 1 billion kg of beef (Capper, 2011b). In addition, waste outputs were also reduced, with modern beef systems producing 82 percent of the manure, 82 percent of the methane, and 88 percent of the nitrous oxide per billion kilograms of beef compared with production systems in 1977 (Capper, 2011b). The carbon footprint for the production of beef has been reduced by 16 percent as well (Capper, 2011b). The specific gains attained from increased feed efficiency in ruminants are discussed in Box 3-5.
Potential Benefits of Improved Feed Efficiency in Ruminants
Feed efficiency plays a crucial economic and environmental role in the production process for ruminant animals. Feed costs have historically accounted for 50-70 percent of beef production costs (Shike, 2013). Feed efficiency is an important determinant in the amount of greenhouse gas emissions intensities produced by livestock systems (Herrero et al., 2013). The nutrition received by a dairy cow affects the emission intensities produced by that animal and its waste (Mitloehner, 2014); more efficient nutrient use decreases costs as well as improves the surrounding environmental quality (Chesapeake Bay Foundation, 2014). Using intensive production processes to promote efficient feed use provides an opportunity to decrease environmental emissions and costs of production. Intensive production processes require particular attention to proper handling of wastes, and are far more likely to attract local public concern (NRDC, 2014).
The U.S. dairy industry realized a 59 percent increase in milk production with 64 percent fewer cows in 2007 than in 1944. As a consequence, greenhouse gas (GHG) production from the industry decreased 41 percent (Capper et al., 2009). In 1944, the average herd contained six cows that were fed a pasture-based diet with some supplemental grain (e.g., corn, soybean meal). Artificial insemination was in its infancy, and neither antibiotics nor supplemental hormones were available for animal use (Capper, 2011a).
By 2007, genetic improvements (e.g., artificial insemination, embryo transfer, sexed semen), the use of hormones for reproductive management, and improved animal management and nutrition resulted in the dairy industry requiring 21 percent of dairy animals, 23 percent of the feedstuffs, 10 percent of the land, and 35 percent of the water needed to produce an equivalent amount of milk compared to 1944. As a result, animal waste and carbon footprint per unit of milk were reduced 24 percent and 63 percent, respectively (Bauman and Capper, 2010; Capper, 2011a). Although the production volume of milk and beef per animal increased due to improvements in all fronts, genetic selection for individual feed efficiency in dairy and beef has never been widely researched, developed, and implemented as it has in the poultry and pig industries. Recently, some research has been done, but the opportunities for improvement are great.
The poultry industry has seen increases in the rate of gain and feed efficiency over the past 50 years (Havenstein et al., 2003; Havenstein, 2006). Havenstein et al. (2003) estimated that 85 to 90 percent of the improvement in broiler performance is attributed to genetics and 5 to 10 percent to nutrition and nutrition management. Pelletier et al. (2014) compared the environmental footprint of the egg industry in the United States in 1960 and 2010. Feed efficiency, feed composition, and manure management were the three primary determinants of the environmental impact of egg production. Per kilogram of eggs produced, the environmental footprint for 2010 was 65 percent lower in acidifying emissions, 71 percent lower in eutrophying emissions, 71 percent lower in GHG emissions, and 31 percent lower in cumulative energy demand compared to 1960 (Pelletier et al., 2014). Reductions in the environmental footprint were attributed to the following: (1) 27 to 30 percent to increased efficiencies of background systems, (2) 30 to 40 percent to changes in feed composition, and (3) 28 to 43 percent to increased bird performance (Pelletier et al., 2014).
In the United States, aquaculture is the fastest growing segment of agriculture, growing at a rate of 10 percent annually, and production levels have essentially doubled every 10 years. From 2007 to 2012, the number of total farms devoted to aquaculture in the United States decreased 27 percent, from 4,896 to 3,586 (USDA, 2014). Approximately 35 percent of the reduction was attributed to decreases in catfish farms as the total value of this farmed crop decreased from $461.9 to $375.9 million. The decrease in farms was primarily due to the demise of small farms that were unable to compete with larger farms, given the increased costs of operation. Most of the other categories of culture fisheries in the United States, including other food fish, sportfish, crustaceans, and mollusks, increased in value despite a reduction of total farms for most of these groups. From 1950 through 2007, production increased from 61,883 to 528,045 tonnes. From 2008 to 2012, production remained at approximately 420,000 tonnes (Olin, 2011) and meeting the increased per capita seafood consumption was due to imports amounting to $82.6 million in 2012 (NSTC, 2014).
The early aquaculture enterprise was devoted to maximizing rather than optimizing production, with marginal attention to sustainability issues. In addition, some enterprises were not successful because management practices were implemented without important information about the biology of the species under culture. In the absence of this baseline information, effective management practices to ensure consistent and efficient production were lacking. The concern for the aquaculture enterprise adversely affecting the environment led to a substantial amount of research transitioning to developing culture strategies based on sustainability concepts complemented by awareness of policies, existing infrastructure, and current and anticipated construct of markets. In comparison to its terrestrial animal production counterparts, the aquaculture enterprise is comparatively young. Accordingly, the potential of biotechnological advances to increase both productivity and efficiency is very high. The application of existing technologies is now strongly based on biological concepts, mitigation of adverse environmental effects, and management of ecosystem balance whereby in some cases aquaculture impacts are actually characterized as positive relative to ecosystem services (Millennium Ecosystem Assessment, 2005).
Biotechnological research with aquaculture species already has a strong innate foundation in achieving efficiency and sustainable intensification because among animal agricultural species, fish are the
most efficient converters of feed to weight (feed conversion ratio). This efficiency is the result of their physiology and environment, whereby caloric demands for certain metabolic functions correspondingly reduces loss of consumed calories in the form of protein and fat. For example, the feed conversion ratio for salmon is 1.2 whereas this ratio is 8.7 for beef, 5.9 for pork and 1.9 for poultry (NOAA, 2014). These characteristics represent important opportunities for the expansion of animal aquaculture products as a source of protein. Greater emphasis on the production of lower-trophic-level species of fish and crustaceans would yield more efficiently produced and sustainable animal protein. In addition, Åsgård and Austreng (1995) noted that approximately 30 percent of protein, fat, and energy contained in feed is retained in the edible part of salmon, whereas 18, 13, and 2 percent is retained in the edible part of chicken, pigs, and sheep, respectively. Therefore, among animal agricultural species, fish, crustaceans, and other aquaculture products are the most sustainable end product relative to efficiencies of production and yield (i.e., protein for consumption per harvested animal).
Intensive production biotechnologies focus on increased production per unit of space. The systems derived from these technologies have focused on the elimination of any detrimental effects on the environment, particularly waste production (i.e., water pollution per unit of production). In addition, the water footprint for these systems is minimal, being based on water conservation and, at times, water reclamation. For example, the partitioned aquaculture system (PAS) is a self-confined (recirculating) aquaculture system (RAS), whereas the biofloc system is a pond-based system. The partitioned pond and biofloc pond systems have been studied and introduced to eliminate limitations of intensification that are not attainable in the earthen pond/raceway systems that have traditionally been used for farming. Both pond-based systems attempt to adhere to ecosystem management principles. For partitioned pond systems, the goal is to separate different aspects of ecosystem management, such as provision of oxygen, fish feeding, and waste treatment (Tucker et al., 2014). These systems have been the subject of research for many years and are beginning to be accepted as systems that can be cost-effective under commercial culture conditions. Biofloc technology (BFT) systems present many advantages over traditional pond culture systems through improved biosecurity, feed conversion, and water quality control, and increased efficiency in the use of water and land resources (De Schryver et al., 2008; Hargreaves, 2013).
Bioflocs are aggregates of algae, bacteria, protozoans, and particulate organic matter (feces, uneaten feed) that serve as food sources. The populations of bacteria that are part of the bioflocs remove potentially harmful concentrations of nitrogen and phosphorus, thereby ensuring that any waste products contained within the effluent from such systems will not be detrimental to the environment. With the consumption of flocs being an added source of nutrients for the farmed species, feed costs can be reduced because the proportional amount of protein in feeds can be reduced. BFT systems are an application of ecosystem management, have been in commercial use since the beginning of the 21st century, and currently are limited to the culture of shrimp and tilapia. There are many variations of biotechnology, and a greater understanding of the principles common to corresponding systems are needed before application to other aquaculture species can be realized.
RAS development and use have progressed, but this technology must continue to be improved with the goal of cost-effectiveness (Malone, 2013). The principal characteristic is a closed-loop design that allows a significant reduction of water and land use (i.e., environmental footprint). In addition, environmental conditions are controlled and not subject to seasonal variations, which allows for the optimization of growth under high density (intensive) culture conditions. An RAS also offers complete and convenient harvesting, rapid response to and effective control of disease, and the flexibility of being able to locate production facilities near large markets. Within the system, accumulation of harmful waste material due to intensive culture is avoided through a design that includes both biological (bacteria) and physical (filters) controls. This is an intensive production system that minimizes water and land resource inputs and effectively treats waste; however, there remain many potential issues facing the success of RAS systems (Box 3-6). Cost-effectiveness among RAS designs will be based on the scale and components of the system. Investment costs are a primary economic feasibility consideration (Losordo et al., 1998), and increases in investment cost per weight of production will translate into increases in the production cost of the product that will be transferred to the consumer. Future research must focus on species-specific designs and related costs that will reduce energy demands. Despite carnivorous species commanding a higher value in the marketplace, their successful RAS culture will also depend on the replacement of high-protein fish meal and fish oil–containing feeds with more sustainable and economically practical feeds. These feeds will be based on research that
evaluates the effectiveness of the underdeveloped sources of protein in the form of insect, worm, or marine invertebrate meals and oils from algae and yeasts (NOAA and USDA, 2011).
Aquaculture production has the potential to increase significantly through the development and acceptance of biotechnological advances that will permit sustainable intensification via offshore cage culture. Culture in sea cages, particularly salmon, has advanced during the last two decades, and continued technological advances in the design, maintenance, and management of and information on monitoring from sea cages are necessary if the goal of increasing marine-based aquaculture production is to be realized (Vielma and Kankainen, 2013). Sea cages must be designed with ecosystem management in mind, particularly for offshore use. With these advances, commercialized cage culture could be designated or confined to certain zones where the protection of wild populations would be upheld and the possible conflicts of resource use would be minimized. Integrative aquaculture and
Economic Feasibility of Recirculating Aquaculture Systems (RAS)
RAS are closed-loop intensive production systems requiring small amounts of water input and generating nearly zero waste. These unique properties, yielding aquaculture products while imposing limited environmental impacts, poise RAS to meet the key needs of a sustainable aquaculture production system (Martins et al., 2010); however, this technology is facing a steep challenge in becoming economically viable. Local Ocean, a company receiving popular attention for producing fish using RAS, had been operating at a loss for its entire existence and lost its main investors in 2013 (Wright, 2014). Because of high upfront costs spent on curating an environment for aquaculture and high perceived risk, the economic viability of RAS is not necessarily attractive for investors (Wright, 2014). This poses a critical problem if sustainable systems such as RAS are to be developed and adopted in the aquaculture industry. Some analyses, however, conclude that RAS may have good profitability for niche and target markets (Federation of European Aquaculture Producers, 2013). RAS provide a valuable opportunity to pursue intensive aquaculture production with limited environmental impacts, but must first clear economic hurdles to be adopted on a larger-scale.
ecological research need to be conducted to develop a strong understanding of the tradeoffs between technological advances and ecosystems.
Not all species that are commercially cultivated will be amenable to intensive culture systems such as RAS and PAS because management of the basic biology of some species may not be applicable to such systems. Farming such species will accordingly warrant semi-intensive and, most probably, pond-based systems. Although production per unit of land is lower than that of intensive systems, the cost of feed and adverse water quality effects that lead to disease are significantly reduced, which contribute to profitability and economic sustainability. Research and corresponding biotechnological developments are needed for less intensive systems and must be guided by similar principles of sustainable management practices involving efficient resource use.
Technological developments in finding substitutes for fish meal and fish oil in formulated diets have been realized. During the past 15 years, the ratio of the weight of fish meal and fish oil in feed to the weight of fish produced has decreased from 3-4.1:1 to 1.5:1, demonstrating proportionately lower levels of or no fish meal in feeds produced for aquaculture (Tacon et al., 2011), but more research to find effective and efficient substitutes is needed to attain sustainable intensification. This need is particularly acute for U.S.-based production of carnivorous fish and crustacean species. Because of sources and the market for these materials, the United States has little control over prices and quantities sold. As of 2012, 35 percent of the fish meal used in aquaculture feeds was derived from wastes of fish processing rather than whole fish from captured fisheries (FAO, 2014b). An understanding of the nutrient value of fish meal derived from the combined processing waste of capture (natural fisheries) and culture (aquaculture) fisheries relative to the traditional “trash fish” source is essential. Identified nutrient deficiencies could be managed through appropriate, cost-effective enhancements.
In 2007, NOAA and USDA began a consultation program with a variety of stakeholder groups to synthesize information and provide future recommendations for the development and availability of effective and alternative (i.e., not fish meal– or fish oil–based) feeds for aquaculture. These efforts were designed to identify and prioritize research that would lead to results considered essential in realizing sustainable intensification. The cost of feeds increased threefold from 2002 to 2012, and demand and vacillations in availability, mostly originating from South America, of this nonrenewable resource was a
strong impetus. The study produced a group of 20 recommendations (Appendix L; NOAA and USDA, 2011).
As the preceding examples demonstrate, researchers in animal science disciplines have been instrumental in developing new technological applications for producing efficient and safe food. Through these advancements in animal production and food processing, the food industry (including crop production) has better optimized the efficiency of production; however, there are public concerns associated with increases in production efficiency made by animal agriculture, ranging from the environmental impacts of concentrated animal feeding operations to the welfare of animals in confinement systems (Box 3-7). The stagnation in public funding of animal science research has hindered researchers’ abilities to sufficiently address public concerns about some aspects of U.S. production systems that have led to increased productivity, including aspects that negatively affect animal welfare and environmental sustainability. Although productivity gains have occurred in the past several decades because of publicly funded animal science research, the current stagnation in funding may result in a slowing of productivity gains right at a time when the increase in global demand for animal protein is accelerating.
Biological Limits to Productivity?
As described in this chapter, animal science research on topics such as genetics, nutrition, and physiology have led to striking increases in animal productivity over time, usually with concomitant decreases in the environmental impacts of animal protein production. These increases in productivity, however, have sometimes come at the cost of negative effects on animal health, leading some academics to suggest that we may be approaching the biological limits of productivity (Grandin and Johnson, 2009). For example, there have been increasing problems with musculokeletal disorders in poultry and dairy cattle, leading to high rates of lameness. It is estimated that 30 percent of dairy cattle in the United States and Canada experience problems with lameness (Hoard's Dairyman), and a similar percentage of broiler chickens have gait disorders (Hocking, 2014). The high egg-laying rate of commercial laying hens is associated with the development of osteoporosis, since bonecalcium is depleted to be used for eggshell formation; consequently, nearly 80 percent of hens in some production sys-
tems experience bone breaks at some point during the production cycle (Lay et al., 2011). Although the causes of musculokeletal disorders are multifactorial, a major contributor is genetic selection and management of animals for productivity. Rauw et al. (1998) documented a large number of studies that indicated an association between the selection for production traits and undesirable metabolic, reproductive, and health traits in cattle, swine, and poultry. This finding draws attention to the need for a balanced approach to genetic improvement in livestock. Future research focused on increasing productivity will need to take into account the potential for these kinds of undesirable effects, along with strategies to mitigate or avoid them.
Academic institutions have only limited input in setting overall future directions for animal agriculture research. Seemingly unrelated to any vision of a future of animal agriculture, several animal science departments including dairy and poultry sciences, for instance, were either eliminated or combined with other departments in well-known U.S. agricultural universities (Roberts et al, 2009). A reenvisioning and reinvigoration of the U.S. animal science research enterprise is needed to meet future animal protein demands sustainably.
Regarding productivity and production efficiency, the committee finds that increasing production efficiency while reducing the environmental footprint and cost per unit of animal protein product is essential to achieving a sustainable, affordable, and secure animal protein supply. Technological improvements have led to system/structural changes in animal production industries whereby more efficient food production and less regional, national, and global environmental impact have been realized.
Support of technology development and adoption should continue by both public and private sectors. Three criteria of sustainability—(1) reducing the environmental footprint, (2) reducing the financial cost per unit of animal protein produced, and (3) enhancing societal determinants of sustainable global animal agriculture acceptability—should be used to guide funding decisions about animal agriculture research and technological development to increase production efficiency.
Other Research Priorities
Technological advancements in the animal protein production system, including genetics, breeding, reproduction, nutrition, animal health and welfare, management, food and feed safety, and food product quality, have been critical to improvements in the production of more environmentally friendly and sustainable animal protein products. One research priority in this area includes:
- Research in sustainable intensification should continue to focus on land, energy, water, and nitrogen utilization. The relevant U.S. government agencies should build a professional interagency network with the aim of maintaining sustainable animal production systems.
3-3 Genetics, Genomics, and Reproduction
The genetics of animal species has far-ranging effects in animal agriculture, including reproductive performance, farm economics, productivity, and environmental impacts. Johnson and Ruttan (1997) suggested that the adoption of breeding technologies has been the most significant factor contributing to farm animal productivity, including livestock and poultry, since the 1940s. Adoption of advanced breeding technologies has resulted in positive impacts on farm profits and milk produced per cow, but has negatively impacted cost of production (Khanal and Gillespie, 2013). Animal breeders have effectively manipulated the genomes of food animal species by using the natural variation that exists within a species. Traditional breeding was done in the past in the absence of molecular knowledge of the genes acting on a quantitative locus, and although much progress has been made, efficiency decreases when traits such as fertility, longevity, feed efficiency and disease resistance are difficult to measure and have a low heritability (Eggen, 2012). Selection for these traits must be accomplished using genomic selection, which will require high-quality phenotypic data from animals.
The application of genomics to the design and implementation of animal and poultry breeding programs is now being actively implemented, and the costs of genomic selection tools have greatly declined in recent years. Combined selection for growth, body composition, and feed efficiency continues to deliver 2-3 percent improvement per year in the efficiency of meat production (Gous, 2010), and milk yields will continue to increase by 110 kg per cow per year
(Eggen, 2012). Commercial breeding goals in poultry and pigs has widened considerably since the 1970s, with the number of genetic traits now typically between 30 and 40 (Neeteson-van Nieuwenhoven et al., 2013). Continued movement away from single-production trait selection (e.g., milk yield) toward more indices that take into account animal reproductive performance, animal behavior, animal welfare, form and function, adaptability to environmental change, and longevity will be critical for advancing the sustainability of animal agriculture. Currently, the genome, transcriptome, epigenome, and the metagenome of many species are being investigated by high-throughput sequencing methods. Benefits are already being reported in the improvement of beef quality (e.g., tenderness, marbling) and muscle development or growth (Box 3-8, Hocquette et al., 2007).
Epigenetics is a newer field in animal science investigating the changes in gene expression, not from alterations of DNA sequence, but rather changes in chromatin structure (Funston and Summers, 2013). These changes reflect broad environmental influences that add methyl groups or other structural elements to DNA beyond those involved in basic inheritance. As such, epigenetics can be considered to reflect the effects of nurture on chromosomal activities, which is a way to understand the cumulative exposure to chemical and nonchemical stressors in humans (Olden et al., 2014). Although research has investigated fetal and neonatal programming due to nutritional differences (Soberon et al., 2012; Funston and Summers, 2013), further research is needed to understand the underlying mechanisms of epigenetics and advances in statistics, bioinformatics, and computational biology (Gonzalez-Recio, 2011). Linking researchers with these basic skills to other animal scientists will help bridge gaps between the “omics” and the whole animal. Additionally, longer-term, multigenerational production systems research (particularly for extensive animal production systems) is required to reveal potential epigenetic effects, while simultaneously evaluating the environmental, social, and economic sustainability of different production systems.
Applying Innovations in Genomic Selection to Animal Breeding Programs
Technological developments in genomics are being directly applied in livestock breeding programs, facilitating greater certainty and efficacy in promoting beneficial genetic traits in raised livestock. As a result, genomic selection is being increasingly integrated into breeding paradigms, creating opportunities for efficiency gains and sustainability improvements related to meat and dairy farming. Improvements in genetic sequencing technology have facilitated the discovery of many single-nucleotide polymorphisms (SNPs) in livestock and poultry. These SNPs have allowed for predictive equations to estimate more accurately a calf’s genomic estimated breeding value (GEBV), which in turn has allowed breeders to better select males and females with describable genetic qualities and improved breeding efficiency (Schefers and Weigel, 2012). Being able to genetically screen cattle prior to sexual maturity has allowed breeders to improve the genetic makeup of livestock at a faster rate. Genetic improvement programs based on genomics are currently only used by a small number of commercial dairy producers and almost no commercial beef producers. In fact, only 5 to 6 percent of the beef herds in the United States use artificial insemination. Increasing the adoption of these technologies would accelerate the dissemination of improved genetics.
Emphasis on recent funding has been placed on genomic information and tools, whereas fundamental research on the biology of birds has been neglected (Fulton, 2012). Poultry genetic diversity is needed to better understand gene function and the effects of variation on traits. The tremendous loss of farm animal diversity on a commercial level in the United States needs to be reversed. Microbial genomics is an area that has the potential to transform the breeding industry because adjustments of the microflora could reduce environmental impacts and improve sustainability. As geneticists continue to make improvements in broiler and layer performance, there will be more emphasis on bird welfare and the ability to cope with widely different environments, especially heat tolerance and dissipation (Gous, 2010).
Green (2009) reviewed the role of animal breeders and the challenges they will face in the genomics era. He suggested that animal breeders will need to lead the way in the integration of genomic and
phenotypic data. There will be a need to better understand how the interactions of genes, proteins, mechanisms, and the external environment produce the phenotype of an animal. To accomplish this, animal breeders will need to work with colleagues in physiology, nutrition, muscle biology, growth and development, lactation, immunology, microbiology and economics. The challenge is articulated by Green (2009) in the following quote:
The reduction in number of academic animal breeding programs around the world, and particularly in North America, has resulted in a deficit of human talent and resources ready to take on these challenges. Not only are quantitative geneticists lacking, those few who are being produced in the remaining programs are entering a highly competitive job market where few are remaining in academia, with many of the trained animal breeding scientists being pulled into the plant and biomedical arenas. The need to rebuild infrastructure for developing scientists and expertise in the animal breeding area is critical and must be addressed through new strategies and models. More direct investment of private industry into the funding of these programs is beginning to occur and will need to increase in the near term. Increased reach of federal research programs into the education sector is also needed, principally through the increased availability of research funding in USDA-ARS for graduate student and postdoctoral training. The time may have come for U.S. programs to break down past barriers that have prevented consortia-type funding so that large-scale, common sense interdependent partnerships can be instituted between federal and state agencies, universities, the private sector, and industry commodity organizations. This model has certainly had success in other areas of the world, and the area of animal breeding is one that could benefit greatly from such approaches. Finally, because of the rapid escalation in the development of genome- and phenome-based technologies, the need for public education and outreach efforts has never been greater (Green, 2009).
It has been estimated that less than 10 percent of all current aquaculture production can be attributed to improvement in stocks (Gjedrem et al., 2012). Hence, aquaculture is far behind other animal genetic breeding programs. Genetic selection will generally have an end product of increased production and increased efficiency relative to the amount of feed, reduction in space needed, and the amount of labor required. The potential for high gains in growth in aquatic species has been well documented, but breeding programs remain quite limited. For example, research efforts with European seabass have recently been directed toward selection for high growth rates on diets containing plant-based rather than feedstuffs of fish origin (Le Boucher et al., 2013). Efficiency of use of resources must be the ultimate determining factor in breeding programs, such that breeding for higher production must be weighed against a prioritized array of values. Olesen et al. (2000) argued that in the quest for sustainable production systems, breeding goals include consideration of environmental and social concerns, such that market and nonmarket trait values should be dually examined. Combining marker-assisted selection with classic selection programs will speed up the process of producing those stocks that would have a positive impact on aquaculture production relative to meeting the protein consumption needs of the world. The use of genetic markers (i.e., transgenic fish) has not been positively received by the public, and a strong and sustained educational effort must be made to remove misconceptions of consequences of use of these fish for aquaculture enterprise.
Major advances in genetic editing technologies have been made possible with the development of the TALEs (transcription activator-like effectors) and CRISPRs (clustered, regularly interspaced, short palindromic repeats). These emerging technologies are promising tools for precise targeting of genes for agricultural and biomedical applications (Montague et al., 2014; Tan et al., 2013). In the future, there should be a focused effort on the factors that contribute to faster genetic gain across all species, which include: (1) a greater accuracy of predicted genetic merit for young animals; (2) a shorter generation interval; and (3) an increased intensity of selection because breeders can use genomic testing to screen a larger group of potentially elite animals (Schefers and Weigel, 2012). Genomic breeding strategies and transgenic approaches for making farm animals more feed efficient will be needed (Niemann et al., 2011). It is anticipated that genetically modified animals will play an
important role in shaping the future of feed-efficient and thus sustainable animal production.
3-3.1 Advancements in Reproduction and Transgenesis
The earliest biotechnology procedure used to improve the reproduction and genetics of food animals was artificial insemination (AI), followed by embryo transfer and in vitro fertilization (Hernandez Gifford and Gifford, 2013). With the advent of AI came the opportunity to devise ways to control the estrous cycle for timed AI (Moore and Thatcher, 2006). More recent tools include super ovulation, in vitro production of embryos, cloning, sexed semen, and transgenics (Moore and Thatcher, 2006; Hernandez Gifford and Gifford, 2013). The benefit of cloning is in the increased accuracy in evaluation of bull dams and the acceleration of the rate of genetic progress. In addition, cloning provides a tool for the producer to propagate highly efficient and productive animals that require fewer inputs and a more positive environmental footprint. The transfer of new genetic material into animals via recombinant DNA protocols results in a transgenic animal. This technology has been available for over two decades and has numerous applications in food animal production including the potential to improve productivity, carcass composition, growth rate, milk production, disease resistance, enhanced fertility, and production of animals with reduced environmental impact (Table 3-2; Hernandez Gifford and Gifford, 2013). Despite its potential, the adoption of cloning and transgenics in animals for food use has not occurred because of societal concerns.
Artificial insemination is an example of a technology that was rejected or approached with much hesitation when first introduced and yet became a conventional breeding system in food animals, including specific lines of poultry production. During the last four decades, research has improved the collection and screening process for specific diseases, storage, and delivery of semen to females. This improvement has made the application of artificial insemination a practical and efficient way for breeding across the world with several food animal species. The improvement, in conjunction with several advancements in the research of embryology, including in vitro maturation, fertilization, and culture, has led to efficiency gains in the embryo transfer of food animal species. Embryo transfer is currently considered a way to improve breeding and avoid inbreeding issues that can affect production and cause diseases to spread. Embryo transfer in animals pioneered the application of this procedure in humans. Research finding
recommendations applied to breeding procedures in specific food animal species, including sexed semen, cloning, and gene transfer, have contributed to food production efficiency and protein conversion. Looking ahead, application of reproductive biotechnologies such as cloning and transgenic animals needs to be considered as ways to more rapidly affect genetic change to produce the next generation of superior animals that will benefit the environment, producers, and consumers (Hernandez Gifford and Gifford, 2013).
TABLE 3-2 Examples of Successful Transgenic Food Animals for Agricultural Production
|1999||Increased growth rate, less body fat||Growth hormone (GH)||Pig|
|1999||Increased growth rate, less body fat||Insulin-like growth factor (IGF-1)||Pig|
|2004||Increased level of polyunsaturated fatty acid in pork||Desaturase (from spinach)||Pig|
|2006||Increased level of polyunsaturated fatty acids in pork||Desaturase (from C. elegans)||Pig|
|2001||Milk composition (lactose increase)||α-lactalbumin||Pig|
|1992||Influenza resistance||Mx protein||Pig|
|1991||Enhanced disease resistance||IgA||Pig, sheep|
|1996||Wool growth||Insulin-like growth factor (IGF-1)||Sheep|
|1994||Visna virus resistance||Visna virus envelope||Sheep|
|2001||Ovine prion locus||Prion protein (PrP)||Sheep|
|2004||Milk fat composition||Stearoyl desaturase||Goat|
|2003||Milk composition (increase of whey proteins)||Β-casein κ-casein||Cattle|
|1994||Milk composition (increase of lactoferrin)||Human lactoferrin||Cattle|
|2005||Staphylococcus aureus mastitis resistance||Lysostaphin||Cattle|
SOURCE: Adapted from Niemann and Kues (2007).
Control of avian influenza by genetic modification benefits the poultry industry as well as the consumer. Lyall et al. (2011) demonstrated suppression of avian influenza transmission in genetically modified chickens in which transgenes were introduced without affecting other genetic properties of the bird. Research and education efforts should focus on understanding the barriers to consumer acceptance of such technologies to realize their full sustainability potential. Other areas for research utilizing reproductive technologies include improved semen technologies and cryopreservation (Rodríguez-Martínez and Peña Vega, 2013), improved fertility (Niemann et al., 2011), and development of technologies that will result in greater success for early pregnancy (Spencer, 2013). Early pregnancy translates into higher production and greater economic efficiency and sustainability of food animal production enterprises. Systems approaches that address nutrition, disease mitigation and prevention, environmental effects, and better adaptation through genetic selection will be important.
Further development and adoption of breeding technologies and genetics, which have been the major contributors to past increases in animal productivity, efficiency, product quality, environmental, and economic advancements, are needed to meet future demand.
Research should be conducted to understand societal concerns regarding the adoption of these technologies and the most effective methods to respectfully engage and communicate with the public.
Other Research Priorities
Reproductive technologies, such as artificial insemination and embryo transfer, continue to result in more rapid genetic improvement, especially in ruminants. In addition, epigenetics, which is the study of the impact of relatively subtle alterations of the genetic code through such processes as methylation of DNA bases, is an exciting new research area that shows promise of providing insights into factors related to post-embryo processes that affect animal growth and health. Improved understanding of genetic x environment interactions can further our understanding of production efficiency while considering other aspects of sustainability such as animal welfare. Research priorities for this area include:
- Research in understanding gene–environment interactions, epigenetics, genomics, nutrigenomics, for example, using biotechnological tools and genetic editing should be conducted to meet the goal of production efficiency while also considering other meaningful components of sustainability such as animal welfare.
- Research leading to advances in the integration of genomic and phenotypic information, genomic breeding strategies, obtaining faster genetic gain, greater accuracy of predicted genetic merit, shorter generation intervals, and increased intensity of selection should continue, particularly in aquaculture.
- Resources should be devoted to the new field of epigenetics, with its potential to provide insight into predicting and integrating the effects of multiple growth promoters and stressors into animal agriculture.
- Animal science departments should integrate computational biology and bioinformatics expertise into traditional animal science disciplines in order to capitalize on the potential of genomics, epigenetics, and metagenomics to improve animal husbandry, productivity, and sustainability.
- Reproductive technologies, such as embryo transfer and cryopreservation, should be further developed and utilized to accelerate the rate of genetic gain. Further emphasis is needed on semen characterization, storage, and quality.
3-4 Advancements in Nutrition
Animal science research has contributed significantly to our current understanding of nutrition concepts and principles in energetics (Johnson, 2007), carbohydrates, and lipids (Nafikov and Beitz, 2007), proteins (Bergen, 2007), and body composition and growth (Mitchell, 2007). The first half of the 20th century may be thought of as the qualitative era of nutritional research where most of the essential nutrients and functions were discovered, whereas the second half of the century was a quantitative period, as nutrient requirements, nutrient–nutrient interactions and pharmacologic aspects of nutrients were the focus of animal nutrition research (Baker, 2008). Translation of research into preparing and feeding diets that closely met an animal’s requirements led to increased productivity and efficiency.
Many advances in understanding animal nutrition have been the result of the public funding of animal science research. The committee refers the reader to the following published reviews on nutritional
advancements and innovations that are too numerous to mention in detail in this report: (1) innovations in indirect methods of estimating dry matter intake and digestibility (Burns, 2008); (2) innovations in energy determination (Burns, 2008); (3) innovations in forage nutritive value (Burns, 2008); (4) innovations in the evaluation of harvested forage (Burns, 2008); (5) innovations related to grazing animals (Burns, 2008); (6) landmark discoveries in swine nutrition (Cromwell, 2009); (7) major advances in fundamental dairy cattle nutrition (Drackley et al., 2006); and (8) major advances in applied dairy cattle nutrition (Eastridge, 2006).
With a major focus on genetic improvement, knowing nutrient requirements of animals at their various stages of life is critical to achieving maximum productivity and reproduction and optimal health and preventing performance and health problems. For example, intense breeding resulted in broilers growing faster than their immature skeletal system could support, resulting in leg and health problems (McCarthy, 2013). Energy and nutrient requirements (amino acids, lipids, carbohydrates, water, minerals, and vitamins) of various food animal species are established from the results of animal nutrition research. The National Research Council (NRC) of the National Academies commissions species-specific scientific committees about every 10 to 15 years to review the scientific literature and establish nutrient requirement guidelines. These requirements are used as the gold standard for formulating diets, especially for studies that will be submitted to U.S. regulatory agencies. In addition, in legal cases these requirements are used as the comparator to assure that diets have met or exceeded the requirements of the species of interest.
The NRC publishes requirements for beef cattle, dairy cattle, swine, poultry, small ruminants (goats, sheep, cervids, new world camelids), horses, rabbits, fish and shrimp, dogs, cats, and laboratory animals (NRC, 2014), which are used in many parts of the world. Published NRC requirements that are relevant to the genetic capabilities of animals in 2050 will be critical. Applegate and Angel (2014) reviewed the history of the NRC and nutrient requirement publications and advocate for keeping these documents current. Based on their perception of the historical poultry nutrient requirement guidelines, the definition of requirement may be changing from a requirement to prevent a nutrient deficiency to a requirement to optimize growth or egg production response per unit of nutrient intake. To keep the nutritional requirements of animals current with the genetic advancements, species-specific research needs to continue in many areas, including energy, protein and amino acids,
lipids, carbohydrates, water, minerals, vitamins, models for estimating nutrient requirements, alternative feedstuffs, the effects of environment on requirements, nonnutritive feed additives, feed contaminants, feed processing, feed intake, nutrient excretion and the environment, and growth- and lactation-enhancing products and their effects on nutrient requirements.
Current versions of NRC publications on animal nutrient requirements include chapters that articulate the current research needs as viewed by the committees that review the latest data pertaining to nutrient requirements. For example, gaps in knowledge of swine nutrition include methods of nutrient requirement assessment, nutrient utilization and feed intake, energy, amino acids, minerals, lipids, vitamins, and feed ingredient composition (NRC, 2012, ch. 15). Critical research needs for fish and shrimp include (1) establishment of essential amino acid requirements; (2) an understanding of whether the main difference in qualitative essential fatty acid requirements among species is dependent on environmental habitat or whether feeding habit is equally or more important; (3) a more definitive understanding of the role of carbohydrate sources on metabolism and energy partitioning; (4) micronutrient requirements; (5) delivery of nutrients in different types of manufactured feed and more rigorous methodology to assess bioavailability of essential amino acids in feed ingredients; (6) alternative lipid sources; (7) nutrient interactions among amino acids, fatty acids, soluble carbohydrates, and lipids; (8) delivery of water-soluble nutrients in sinking and larval feeds; (9) application of modern molecular techniques to determine the effects of nutrients on cells and organelles; and (10) gene-specific regulation of physiological processes (NRC, 2011, ch. 17).
Nutritional advancements in food animals are being made to enhance animal reproduction (e.g., long-chain polyunsaturated fatty acids, selenium, and vitamin E), improve the quality and nutritional value of animal products for the consumer (e.g., dietary vitamin E to extend meat shelf-life, enhanced omega-3 fatty acids in eggs, fresh grass to increase conjugated linoleic acid in dairy products), and improve animal health (e.g., copper and gut health, selenium and vitamin E for improved oxidative stability). The crucial need to study and understand the role of gut microflora is analyzed in Box 3-9. Major accomplishments in monogastric nutrition have been made with development of energy systems, amino acids and available amino acids, lipids, carbohydrates, minerals, gut metabolism, and gut microbiome work. Research in
improving the utilization of fiber in feed ingredients for swine, poultry, and aquaculture is needed. For ruminants, major advancements have been in energy metabolism with the development of the net energy system, protein and amino acid requirements, rumen digestion, technology for protecting nutrients (e.g., amino acids, lipids) from microbial degradation in the reticulo-rumen, improved forage digestibility, and lipid and mineral metabolism.
Gut Microflora and the Microbiome
Relatively little is known about the function or the beneficial attributes of many microbes that live in the gastrointestinal (GI) tracts of animals; however, it is clear from studies of many species that the coevolution of animals and microbes led to many symbiotic and commensal relationships between microbes and the GI tract (Hooper and Gordon, 2001; Ley et al., 2008). A better understanding of these relationships could create innovative advances in livestock production to the benefit of the environment, human and animal health, and production efficiency. Selecting animals for breeding stock that have better nutrient retention or altering the microflora in the gut has the potential to increase the efficiency of nutrient use and to reduce waste production and greenhouse gas emissions from livestock. For example, the microbes in the foregut of ruminants could be altered to metabolize nutrients more efficiently, reduce nutrient excretion, and mitigate methane emissions. One method proposed for altering the gut microflora is to increase the amount of acetogenic bacteria in the gut, which decreases the amount of hydrogen available to reduce carbon dioxide to methane (Jeyanathan et al., 2014). Another method is to select breeding stock that produces less methane and uses nitrogen more efficiently, which could decrease ammonia and nitrous oxide emissions and presumably decrease greenhouse gas emissions.
Subtherapeutic levels of antibiotics are administered to livestock, in part, to increase weight gain. In a feeding study comparing pigs fed performance-enhancing antibiotics with those not fed antibiotics, Looft et al. (2012) found that the pigs fed antibiotics had an increase in certain bacterial populations and an increase in energy production and conversion that were related to microbial functional genes. Subtherapeutic use of medically important antibiotics in livestock production is currently under scrutiny because of its possible linkage to increased antibiotic
resistance in humans (CDC, 2013) and the relationship between subtherapeutic antibiotic use and overcrowded housing conditions for livestock (FAO, 2013). It may be that probiotics could be used in the place of antibiotics. Probiotics—live microorganisms suspected of conferring health benefits to the host—are already used as additives to the feed of many kinds of livestock for their ability to increase production efficiency and improve food safety by outcompeting pathogenic microbes in the gut (Callaway et al., 2003). For example, the direct feeding of probiotics to cattle has been shown to decrease fecal shedding of E. coli O157:H7 (Brashears et al., 2003); however, the mechanisms of action for many of these beneficial microbial feeds are poorly understood (Gaggìa et al., 2010).
The existence of successful feeds for the culture of larval fish and crustaceans, particularly marine and estuarine species, limits the ability to increase production. In contrast to live food diets that require much labor and can be subject to variable nutrient composition, formulated diets offer control over nutrient content and substantially eliminate labor. A number of technologies have been used in attempts to deliver nutrients effectively to larval forms; however, success, defined as the exclusive use of these feeds, has been very limited. Technological advances are essential to achieve cost-effective preparation and content of these feeds whereby they will be readily consumed and well digested and assimilated to deliver required nutrients for growth (NRC, 2011).
All of these advancements have led to improved productivity and production efficiency with less environmental waste in the form of nitrogen, phosphorus, and GHG emissions per unit of output; however, not all agricultural systems take advantage of these nutritional advancements that contribute to environmental sustainability. For example, in the U.S. National Organic Program, participants cannot use synthetic amino acids such as lysine, methionine, and tryptophan, which are used to balance the dietary amino acids to better meet the animal’s requirements. Because of this restriction, organic diets may cost more and animal productivity may be reduced with less efficient use of those nutrients, resulting in more nitrogen being excreted into the environment. Many nutritional advancements are not allowed to be used in organic agriculture according to the U.S. National Organic program (list of approved ingredients can be found in the Code of Federal Regulations [7 CFR §§ 205.600-205.607]). Only synthetic methionine is approved for poultry up to specified maximum levels. Additionally, the U.S. National
Organic Program has requirements for the production of feedstuffs, such as the prohibition of synthetic fertilizers and pesticides for 3 years before the feed can be certified organic, which can limit feed availability and increase costs for organic animal production systems (Mainville et al., 2009). Organic crop yields tend to be lower than conventional crop yields; however, the difference in yields is dependent on the system and location (Seufert et al., 2012; Rosegrant et al., 2014). Cows on organic farms produced 43 percent less milk per day than conventional nongrazing cows and 25 percent less than conventional grazing herds (Stiglbauer et al., 2013). Future research on improving crop productivity and feed quality while addressing environmental sustainability concerns and accommodating socioeconomic and cultural needs, regardless of the production system considered (i.e., organic or conventional), will benefit the nutrition of food animals.
The committee notes that understanding the nutritional requirements of the genetically or ontogenetically changing animal is crucial for optimal productivity, efficiency, and health. Research devoted to an understanding of amino acid, energy, fiber, mineral, and vitamin nutrition has led to technological innovations such as production of individual amino acids to help provide a diet that more closely resembles the animal’s requirements, resulting in improved efficiency, animal health, and environmental gains, as well as lower costs; however, much more can be realized with additional knowledge gained from research.
Research should continue to develop a better understanding of nutrient metabolism and utilization in the animal and the effects of those nutrients on gene expression. A systems-based holistic approach needs to be utilized that involves ingredient preparation, understanding of ingredient digestion, nutrient metabolism and utilization through the body, hormonal controls, and regulators of nutrient utilization. Of particular importance is basic and applied research in keeping the knowledge of nutrient requirements of animals current.
Other Research Priorities
Organic animal agriculture is growing in the United States. For example, organic livestock increased from ~56,000 head in 2000 to
~492,000 in 2011, and poultry numbers have steadily increased from 3.1 million to 37 million. Although in certain circumstances organic animal agriculture can contribute to sustainability at the local level, such as by decreasing energy needs for transportation and by lessening the concentration of waste in a single location, there is no evidence to suggest that organic animal agriculture in its present form can be scaled up to make a substantial contribution to current or future needs for animal protein. Research priorities for this area include:
- For organic agriculture to contribute significantly to meeting global protein demand, research directed toward quantifying the potential for organic agriculture to be sustainably scaled up (equal or better environmental footprint per unit of animal protein produced, equal to or more affordable supply of animal protein, equal to or greater efficiency in animal protein production compared to conventional) to meet more than local needs is essential.
- Very high priority should be given to research into how best to enhance informed and respectful engagement between the scientific community and the public on issues related to the potential role of organic agriculture in achieving sustainable local and global impacts on food security.
3-5 Animal Models
3-5.1 Agricultural Animal Models Benefiting Animals
Research using animal models together with characterized diets has been beneficial in advancing animal nutrition and has contributed to what is known about nutrient–nutrient interactions, bioavailability of nutrients and nutrient precursors, and tolerance levels for excessive intakes of nutrients (Baker, 2008). In the last 50 years, efforts were made to understand the biology of animals and poultry in quantitative terms. Baldwin and Sainz (1995) and Dumas et al. (2008) provide a historical perspective to the mathematical models used in animal nutrition as well as a discussion on the mechanistic dynamic growth and lactation models. Many of these mathematical models with sensitivity analyses helped animal science researchers to focus on areas where knowledge gaps needed to be filled and to have major impacts on the biological system as a whole. Other animal models were developed to accurately predict nutrient requirements of animals in different stages of development, including maintenance, growth, lactation, and reproduction. Energy and protein feeding systems exemplified in the NRC nutrient requirement
publications describe the nutrient requirements of more than 20 species of domestic animals and have evolved considerably over the past 40 years. Although systems have remained static, factorial, and largely empirical in nature, mechanistic concepts have been incorporated into the statistical models used in analyses of input-output data and applied in the revised systems (Baldwin and Sainz, 1995). The NRC nutrient requirement publications in the last 15 years for dairy, beef cattle, and swine all contain animal models that use environmental, management, and feed inputs to predict animal requirements and performance. In the future, agricultural animal models will need to become more dynamic and mechanistic, and more integrated into biological systems to reflect and accurately predict whole-animal performance for both research and field applications. They will also need to include consequences for and from environmental change, especially regarding performance as it relates to biogeochemical cycling and climate change. Although the committee believes that comprehensive system models that include soil, crop, animal, land use, for example, would be useful in studying such environmental tradeoffs, the scope of the work focused on animal science research and thus animal models is specifically highlighted in this section. McNamara and Shields (2013) and Lantier (2014) suggest that animal models be used as tools for understanding emerging or reemerging infectious diseases. Biomathematical system models will be needed for integrating nutrition, growth, reproduction, and lactation to predict animal performance. Such models will enhance animal science research in exploring and predicting the effects of different feeds, feeding systems, management, environment, and health.
3-5.2 Agricultural Animal Models Benefiting Humans
Agricultural animal models have been used in biomedical research to study a wide range of physiological and disease factors important to humans (Ireland et al., 2008). Seventeen Nobel Prize winners have used farm animals such as cattle, pigs, sheep, goats, horses, and chickens as research models (Roberts et al., 2009), yet their value is generally underappreciated. “There are numerous examples of compelling domestic species models relevant to diverse areas of biomedical research, including comparative physiology and genomics, cloning, artificial insemination, ‘biopharming’ to produce high-value pharmaceuticals in milk, osteoporosis, diabetes-induced accelerated atherosclerosis, asthma, sepsis, alcoholism, and melanoma” (Roberts et al., 2009). Agricultural animals should continue to be used in biomedical research.
Mathematical animal model systems have been helpful in identifying key areas to research as well as providing a better understanding of the function of biological systems and predicting nutrient requirements and performance. They have also been helpful as models for studying physiological processes and diseases that may have important implications for other animals and humans. Such efforts also are critical to improving our understanding of complex biogeochemical cycling affecting climate and environment, including geographical variability. Research priorities for this area include:
Funding of research to encourage the development of animal models that are more dynamic, mechanistic, with more comprehensive integrated biological systems (i.e., growth, maintenance, reproduction, lactation) is needed to accurately predict whole-animal performance for and provide better assessments of current and potential future practices in animal agriculture.
Funding agencies should increase their emphasis on biomathematical modeling systems research at all levels (e.g., tissue, whole-animal, and production systems levels) and building and strengthening connections between modelers and experimental animal scientists.
3-6 Feed Technology and Processing
Feed technology and processing are important in enhancing productive efficiency and production in food animals. Particle size is important in rate and extent of digestion. Particle size of the diet can be too small and cause health problems such as stomach ulcers in pigs and acidosis in cattle, or too large in size and cause decreased digestibility and reduced feed intake. Heating has become important in deactivating antinutrients in feeds such as soybeans, enhancing starch digestibility through gelatinization in the steam flaking of corn and milo, and pelleting and extrusion processes; however, too much heat can be detrimental to certain amino acids, vitamins, for example (Institute for Food Technology, 2010). Feed processing is important in dust control and achieving higher feed intakes, maintaining a uniform composition, and reducing waste. Feed technology is important in aquaculture to deliver a floating, slowly sinking or sinking feed depending on the feeding behavior of the intended species. Better methods are needed to deliver dietary nutrients that are acceptable to the animal as well as contain the required nutrient density without suffering quality. This has
involved grinding, pelleting, extrusion, and coating technologies as well as others. In ruminants, processing of forages and delivering feeds as total mixed rations, which reduces the animal’s ability to sort out feed ingredients so that each mouthful contains the same consistent nutrient profile, has proven to improve production by reducing the variability of nutrient intake.
For a review of issues and challenges in feed technology pertaining to particle size, pelleting, and feed uniformity, see Behnke (1996) and Neves et al. (2014) and for a review on heat treatment and extrusion in animal feeds, see the proceedings of the 2nd Workshop, “Extrusion Technology in Feed and Food Processing” (Institute for Food Technology, 2010).
Feed technology and processing is important to improving feed acceptability to the animal, feed efficiency, and animal health, and reducing feed wastage. One research priority in this area includes:
- Research in feed technology and processing should continue to make further step changes in the most efficient utilization of current and alternative ingredients in animals with minimal wastage (e.g., research areas of potential significance include improvements in water stability for aquaculture, enzyme stability in pelleting feed).
3-6.1 Alternative Feedstuffs
The feed industry and food animal producers are constantly looking for alternative feed ingredients that are more economical but maintain the right digestible nutrient profile, no contaminants, and compatibility with other currently used ingredients, and are organoleptically acceptable to the animal. Typically, co-products produced in making human food are used and include bakery byproducts, wheat midds, wheat bran, corn gluten feed, corn gluten meal, brewers’ grains, fish meal, meat and bone meal, poultry byproducts, peanut meals, peanut hulls, rice mill byproduct, rice hulls, soybean meal, canola meal, almond hulls, citrus pulp, sugar beet pulp, sugar cane molasses, yeast, animal fat, whey, and blood meal. Other co-products are produced in nonfood industries such as biofuels (wet or dried distillers’ grains, glycerin), cotton production (cottonseed meal, cottonseed hulls), fermentation waste products, and algae. Feed ingredients that do not compete with human food sources and can be converted to value-added nutritious animal products contribute to
food security and are more favorable in terms of carbon footprint and environment.
Fish meal and fish oil, for example, are the main protein and oil sources used in the formulation of aquaculture diets, especially for carnivorous fish such as salmon. In 2007, principally in response to the use of unsustainable ingredients (feedstuffs) such as fish meal and fish oil in feeds for aquaculture, NOAA and USDA initiated the study of alternative feedstuffs and feeds for aquaculture. There is a finite supply of fish meal and fish oil, and with increased demand for salmon, alternative less expensive protein and oil sources are being advocated and evaluated (Naylor et al., 2009). Soybean meal can partially replace fish meal, and rapeseed oil can partially replace fish oil. However, there are limitations because alternative ingredients do not have the correct nutrient profile to provide 100 percent replacement of currently used feeds. For example, fish oil contains high levels of long-chain polyunsaturated fatty acids (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) that vegetable oils do not have. Thus, a minimum amount of fish oil must remain in the diet or an alternative source of EPA and DHA needs to be provided. Recently, insect meal has been being evaluated as a protein source. Use of insect meal derived from the larvae of insects feeding on seafood waste is an attractive area of future research (van Huis et al., 2013). Research has been devoted to an evaluation of the use of fish offal (processing waste) for the mass culture of insects that in turn can be prepared as a meal for use as an ingredient in formulated feeds. This is a promising area of research that offers the potential impact of ultimately eliminating the dependence on fish meal and fish oil as ingredients in feeds for carnivorous species. The insect meal would serve as a good source of amino acids and fatty acids that characterize fish meal and fish oil. For rainbow trout, Oncorhynchus mykiss, soldier fly prepupae served as an effective substitute for 25 percent of fish meal and 38 percent of fish oil ingredients. These larvae can be grown on fish offal (waste), and noteworthy increases in total tissue lipid (30 percent) and n-3 polyunsaturated fatty acids (3 percent) were observed in just 24 hours when compared to tissue of larvae that were fed on manure for an equivalent period of time (St. Hilaire et al., 2007).
Continued efforts need to be directed toward the use of mixtures of processed animal protein ingredients and plant-derived meals as partial or complete substitutes. Cost and benefits of these alternative feedstuffs can only be assessed through an understanding of the content and
availability of nutrients in the feedstuffs, as well as the environmental footprint associated with their preparation and production. Research in improving the nutrient capture from co-products by livestock, poultry, and aquaculture is critically needed, especially the improvement in nutrient utilization of fiber by poultry, swine, and aquaculture. Research should also be directed to the development of technology of mass culture of microorganisms (e.g., algae, yeasts) using food or industrial waste streams as the substrate, and to the use of oilseeds that contain important required nutrients such as long-chain polyunsaturated fatty acids that are found in fish meal and fish oil and can potentially serve as ingredients of formulated feed (Byrne, 2014). Wastes (e.g., protein and oils) derived from the production of biofuels and byproducts from the processing of terrestrial animals also hold potential as alternative feedstuffs. Typically, the industry that is generating the new product funds the animal science research needed to commercialize the product. For example, Texas A&M AgriLife is evaluating algal residue for animal feed after the biofuel has been extracted (Texas A&M University, 2012). The environmental impacts of producing an alternative feedstuff will also need to be assessed (NOAA and USDA, 2011).
Potential waste products from the production of human food, biofuel, or industrial production streams can and are being converted to economical, high-value animal protein products. Alternative feed ingredients are important in completely or partially replacing high-value and unsustainable ingredients, particularly fish meal and fish oil, or ingredients that may otherwise compete directly with human consumption.
Research should continue to identify alternative feed ingredients that are inedible to humans and will notably reduce the cost of animal protein production while improving the environmental footprint. These investigations should include assessment of the possible impact of changes in the protein product on the health of the animal and the eventual human consumer, as well as the environment.
3-6.2 Feed Additives, Growth Promotants, and Milk Production Enhancers
Feed additives and growth promotants are used to enhance productivity and improve feed efficiency, often resulting in decreased environmental impacts per unit of output (Capper and Hayes, 2012). In the U.S. National Organic Program for animal production, use of most of these additives and growth promotants is not allowed. Feed additives may improve feed intake, alter the gut microbiome in a positive way, enhance nutrient absorption, decrease antinutritives, increase digestibility of fiber, improve mineral utilization such as phytate phosphorus, improve carbohydrate metabolism, decrease methane production and improve health. Examples of feed additives include exogenous enzymes, yeast, ionophores, organic acids, probiotics, and prebiotics. Ionophores, such as monensin, lasalocid, lailomycin, salinomycin, and narsin are rumen modifiers that improve feed efficiency while potentially reducing methane emissions in ruminants (Appuhamy et al., 2013).
Another area of feed-based research that has the potential of increasing production efficiency of aquaculture organisms is the use of probiotics and prebiotics in feeds. These live microbial or nondigestible compounds, such as oligosaccharides, are feed additives that have shown promise by increasing feed efficiency and/or immune response or resistance to pathogenic infection (NRC, 2011). Both additives have been shown to alter the resident bacteria within the gastrointestinal tract of fish and crustacean species. Although there are limited reports about the benefits of probiotics and prebiotics in aquaculture organisms, future efforts to increase production efficiency from their use are expected. Laboratory research that identifies positive responses to probiotics and prebiotics ideally should be complemented by testing under production settings.
Exogenous enzymes have improved the digestibility of feedstuffs and reduced waste (Meale et al., 2014). There is a need for a better understanding of the enzymatic machinery involved in cell-wall degradation through a better understanding of the microbial microbiome. The use of dietary enzymes as a means to increase the availability of nutrients to fish and crustacean species has had limited application, but experimental results have shown positive effects on the digestibility of protein and carbohydrates (Buchanan et al., 1997; Glencross et al., 2003). The lack of stability of these enzymes when exposed to high temperature as part of the aquafeed manufacturing process is still a challenge (NRC, 2011). A dietary supplement of phytase to increase the
digestibility of phytic acid, a source of phosphorus contained in plant feedstuffs, has been successful in releasing phosphorus for uptake (Gatlin and Li, 2008). This procedure also has a positive environmental effect because less undigested phosphorus is then released into the environment as a potential pollutant. Biotechnological advances are needed whereby enzymes can be added to diets without surrendering their specific metabolic capabilities.
Food and Drug Administration–approved growth promoters and milk production enhancers have been key technologies resulting in improved production efficiencies in the U.S. cattle industry for over 50 years (Table 3-3). For example, researchers recently reviewed the results of 26 peer-reviewed journals or reviews by regulatory agencies on the efficacy and safety of sometribove zinc suspension (rbST-Zn), a form of recombinant bovine somatotropin, in lactating dairy cows (St-Pierre et al., 2014). The results of the meta-analysis indicated that rbST-Zn administration to dairy cows effectively increases milk production with no adverse effects on cow health and well-being. The findings are consistent with anecdotal reports regarding the use of recombinant bovine somatotropin in more than 35 million U.S. dairy cows over 20 years (St-Pierre et al., 2014). The development through research, adoption, and application of these feed additives, growth promotants, and milk production enhancers has contributed to food security and sustainability in several ways: (1) production costs have been reduced through reductions in the amount of feed required per unit gain; (2) the land necessary to produce equivalent amounts of food for consumers has been reduced; (3) the production of GHGs has been limited by reducing the number of animals required to produce equivalent amounts of beef or milk; and (4) cost savings have been extended to consumers by providing a year-round affordable supply of beef and milk at reduced prices (Johnson et al., 2013).
FDA-approved feed additives, growth promoters, and enhancers of milk production have been successfully used for decades, resulting in improved efficiency and economics and reduced environmental footprint. In aquaculture production systems, for example, feed additives called prebiotics or probiotics have shown promise for increasing growth/feed efficiency and/or immune response or resistance to pathogenic infection. Research priorities for this area include:
TABLE 3-3 Chronological Sequence of FDA Approval of Growth and Lactation Promotants Used in the U.S. Beef and Dairy Cattle Industries
|Growth Promotant||Year of FDA Approval|
|Oral diethylstilbestrol (DES)||1954|
|Estradiol benzoate/progesterone (steers)||1956|
|Estradiol benzoate/testerone propionate (heifers)||1958|
|Oral melengestrol acetate (heifers)||1968|
|Zeranol (36 mg) implants (steers)||1969|
|Oral DES removed from the market||1972|
|DES implants removed from the market||1973|
|Silastic estradiol implant (cattle)||1982|
|Estradiol benzoate/progesterone (calves)||1984|
|Trenbolone acetate (TBA) implants (cattle)||1987|
|Estradiol (17-β)/TBA implants (steers)||1991|
|Estradiol (17-β)/TBA implants (heifers)||1994|
|Zeranol (72 mg) implants (cattle)||1995|
|Estradiol (17-β)/TBA implants (stocker cattle)||1996|
|Ractopamine hydrochloride (cattle)||2003|
|Zilpaterol l hydrochloride (cattle)||2006|
|Increase Milk Production Efficiency Agents||Year of FDA Approval|
|Bovine somatotropin (lactating dairy cows)||1993|
|Monensin sodium (dry and lactating dairy cows)||2004|
SOURCE: Adapted from Johnson et al. (2013).
The committee supports the initiation and/or the continuation of research devoted to the development of products that enhance growth and lactation of animals.
Research needs to be conducted to identify prebiotics and probiotics that have documented efficacy in the improvement of growth and immunocompetence.
Social science research needs to be conducted to understand the social ramifications and public concerns about the use of these technologies in the production of animal protein and how to better engage and respectfully communicate the substance of the technology and its benefits and risks to the public, to food security, and to a sustainable environment.
3-7 Animal Health
It is important from a food security and food safety standpoint that food animals are healthy, animal diseases are not transmitted to humans, and animal products are safe and affordable for human consumption.
Animal health is an essential component of sustainable animal production systems. Highly contagious animal diseases can be a major disruption to global food security. Since the creation of the World Trade Organization, animal health issues have been a major hurdle for trading animal protein globally, and animal health issues are becoming a trade component for the United States and other countries. USDA ARS and NIFA have given top priority based on budget allocation to addressing animal health issues in the United States. In 2010 and 2011, USDA ARS and NIFA held stakeholder workshops that determined the high-priority health issues by species in which funding should be directed (see Appendixes D and E).
The progression in understanding animal disease ecology has led to better approaches to managing diseases that have serious negative impacts on food animal populations. During the last four to five decades, vaccination for highly contagious animal diseases has improved both in its delivery system and in vaccine production. The majority of these diseases with high economic consequences can be controlled or even eradicated from specific regions if disease intervention measures are taken. These intervention measures, including vaccination, teat dipping, dipping and housing management were researched by veterinary and animal scientists prior to being recommended to animal agriculture industries. Animal agriculture and society in general have gained major benefits from research on animal diseases, with the ability to improve animal welfare as well as reduce the risk of transmitting these diseases to humans. Advancements have resulted in less human labor so that producers can handle a greater number of animals at improved efficiencies, increasing output per animal as well as per farm. Innovative research has also lead to better animal health, such as the use of an antibacterial delivery system for aquaculture (Box 3-10).
With the potential future elimination of subtherapeutic use of medically important antibiotics, research is needed to discover substitutes that will provide the same or greater benefits in improved feed efficiency, disease prevention, and overall animal health. Confronting disease issues will be essential for private investment in aquaculture operations in the future. More research is needed to address the systems-specific production losses due to disease. Many of the disease problems arise from poor management practices that compromise the value and nutritional value of the animal product. Intensification that is sustainable will require responses to disease other than the use of medically important antibiotics. Effective responses to disease lie in
proactive investigations of the physiological relationships between host and pathogen. To meet these challenges, a specific animal model needs to be developed whereby an understanding of this basic physiology of host and pathogen can be achieved. A model organism could be used to establish the basis for understanding this relationship.
The Adoption of a Novel Antibacterial Delivery Method in Aquaculture
Preventing disease in aquaculture populations is critical to the industry’s financial success and the well-being of raised fish, because losses due to disease pose a serious challenge. For example, the Chilean salmon farming industry lost $2 billion, 30,000 jobs and 350,000-400,000 tons of fish from an infectious salmon anemia outbreak in 2007 (Kobayashi and Brummett, 2014), and climate change will likely lead to further outbreaks due to sea surface temperature changes (Handisyde et al., 2006). The collection of farmed fish is usually achieved through the processes of netting, grading, or pond draining (Humane Society of the United States, 2014). The frequent use of nets to sort and collect aquaculture yields presents a unique opportunity for the delivery of antibacterial agents to protect farmed fish and marine animals. The application of active substances on netting has already been tested and used for antifouling purposes on fishing equipment (Bazes et al., 2006) and as such, provides a possible medium for antibacterial coating to protect aquacultures from diseases and parasites of concern. The potential for protective coatings on nets is enormous in terms of preventing disease and minimizing aquaculture losses; however, there are substantial risks, such as the danger of creating antimicrobial-resistant bacteria in humans and animals (Park et al., 2012). If managed effectively and applied appropriately, antibacterial coatings for netting could improve aquaculture yields and better protect raised species.
In aquaculture, the zebrafish is an attractive model to gain the necessary understanding of the physiological relationships of the host and the pathogen whereby appropriate management procedures, whether preventive or therapeutic, can be implemented. The development of a standardized diet for zebrafish culture will be essential to these efforts because nutrition must be controlled. Otherwise, responses may vary depending on the diet fed to the model. Immersion vaccines were the
first type of vaccines developed for fish, and vaccination methodology has progressed to injection of antigens into the body cavity (Sommerset et al., 2005). Most of the vaccines are produced by animal health companies, and an array of them are used in the aquaculture industry with a focus on salmonid species (i.e., salmon and trout) but delivery through feed has not achieved success because of breakdown and resulting lack of effectiveness (Sommerset et al., 2005). Vaccines in fish species are most effective against bacterial rather than viral diseases (Sommerset et al., 2005). Killed virus–based vaccines are not effective unless delivered at high dosages and by injection, conditions that compromise cost-effectiveness. Live-virus vaccines have yet to be developed or used because of concerns about environmental safety (Sommerset et al., 2005). Research devoted to the possible development of vaccines for invertebrates, specifically cultured crustaceans, has yielded inconclusive results (Sommerset et al., 2005); however, Rowley and Pope (2012) offer evidence that vaccination through an immune priming mechanism may have application, but will probably be species and pathogen dependent.
Vaccine development and delivery in aquaculture appear to be frustrated by the limited knowledge of the immune systems and the effect on other organisms and the consumer. Research devoted to understanding the innate immune response of aquaculture species should lead to the identification of stimulants that will promote immunocompetence. Appropriate standards related to the assessment of the health status of an array of animal and aquaculture species need to be developed. The identification of DNA probes that would determine whether or not live or processed food animals are pathogen-free could lead to attractive, field-based “health tests” that could be used by veterinarians, field technicians, or farmers. Research is needed on scientific, managerial, and educational tools and practices to enhance identification of and response to an animal disease outbreak. Continuing research is needed on technological tools that can rapidly identify diseases, defects, or contamination in animal products.
The subtherapeutic use of medically important antibiotics in animal production is being phased out and may be eliminated in the United States. This potential elimination of subtherapeutic use of medically important antibiotics presents a major challenge.
There is a need to explore alternatives to the use of medically important subtherapeutic antibiotics while providing the same or greater benefits in improved feed efficiency, disease prevention, and overall animal health.
Animals must be healthy to achieve optimum production and efficiency. Animal diseases can result in market and trade interruptions, thus impacting food security, and may pose a significant human health threat. Advancements in animal health such as through vaccines and other preventive measures have resulted in less human labor, so that producers can handle a greater number of animals at improved efficiencies, increasing output per animal as well as per farm. Development of vaccines, however, is often frustrated by a limited knowledge of immune systems. Development must include cost analyses relative to production, delivery, and effectiveness, with particular emphasis on the development of successful vaccines using live viruses. Research priorities for this area include:
Funding agencies should support research to address the entire production system’s specific production loss due to disease. The research should integrate various components in the production system and not restrict it to animal health aspects. An example is PED virus, for which production, animal movement, and feed ingredients must be considered (see Box 2-1).
Scientific, husbandry, and educational tools and practices to enhance identification of and rapid response to an animal disease outbreak must be a focus of public-sector research. Continuing research is needed on technological tools, including biological models that can rapidly identify diseases, defects, or contamination in animal products.
Research should continue to achieve an understanding of the innate immune response of species, include aquatic species, leading to the identification of stimulants that will promote immunocompetence and the rapid development and production of efficacious vaccines or other preventive measures.
Research should be conducted to address threats of new and emerging zoonotic diseases that may be exacerbated by climate change and intensification (e.g., tickborne diseases).
3-8 Animal Welfare and Behavior
Animal welfare research was considered a high priority for many of the stakeholders participating in the 2011 USDA NIFA animal health workshop (Appendix F). The scientific study of animal welfare is still relatively new compared to other disciplines and fields within the animal sciences. The empirical evaluation of animal welfare is a complex undertaking, and there is no single definitive indicator (Mason and Mendl, 1993). Such evaluation involves investigation of biological functioning (e.g., health and physiological normality), the consequences of an animal’s ability or inability to perform highly motivated behaviors, and their subjective states (e.g., pain, fear, pleasure) (Fraser, 2008a,b). There is an ongoing need to develop and validate new experimental methodologies for welfare assessment, particularly indicators of animals’ subjective states (Dawkins, 2006).
Animal welfare research is, of necessity, multidisciplinary, although for historical reasons discussed in Chapter 2 the development of the field was stimulated by concerns about animal production systems that restricted animal movement, and thus applied animal behavioral scientists (ethologists) initially played a major role (Fraser et al., 2013). Note, however, that ethology is an important discipline in the animal sciences in its own right, independent of its importance to animal welfare. An understanding of animal behavior is important to improve animal management and productivity in many production systems (Price, 2008). For example, animal behavior research has been influential in improving reproductive performance through understanding factors affecting expression of mating behavior and success. It has also contributed to better management methods for animals kept in social groups, methods for improving maternal care of offspring, and better handling techniques for food animals.
Ethology is also still a key discipline within animal welfare science; however, many other disciplines now contribute to the increasing body of animal welfare research and research application (Fraser, 2008a,b; Mellor et al., 2009; Appleby et al., 2011; Fraser et al., 2013) including physiology (e.g., stress, environment, neurophysiology), veterinary medicine (e.g., preventive, pathology, epidemiology), agricultural engineering/environmental design, comparative psychology, nutrition, genetics, microbiology and social sciences (e.g., the study of human–animal interactions).
Despite being a relatively new field, there is now a significant research base for animal welfare (Fraser et al., 2013); the output of scientific publications has increased by 10-15 percent annually during the last two decades and nearly half of the approximately 8,500 animal welfare papers in the ISI database were published in just the last 4 years (Walker et al., 2014). There have been many important theoretical and applied research gains. Theoretical advances include the development of testing and assessment methodologies, such as assessing animal preferences, feelings, and motivational states (Widowski, 2010). Research has also increased knowledge regarding animal pain and its alleviation (Stafford and Mellor, 2011), as well as the factors that lead animals to develop detrimental abnormal behaviors that necessitate the use of painful management practices such as beak trimming and tail-docking (Mason and Rushen, 2008). From an applied perspective, animal welfare researchers have contributed to both knowledge and new technology development for improving animal handling, transport, and slaughter (Grandin, 2010) and alternative housing and management systems (Appleby et al., 2011).
Many of these advances have come about because of a sustained commitment within the European Union to funding animal welfare research during the last few decades. The United States has lagged behind in this effort, and the number of researchers and the knowledge base relative to public concern are now imbalanced (Johnson, 2009). There is a need to build capacity and increase funding for research in animal welfare, with a focus on U.S. production systems and management and in the context of the broader sustainability considerations affecting U.S. agriculture. There is also a need for additional research on animal welfare that incorporates consideration of public values and attitudes and addresses public concerns about topics such as animal feelings and the ability of animals to perform their natural behaviors.
While some animal welfare research will be commodity specific, there are also critical overarching research areas (FASS, 2012; Walker et al., 2014), some of which overlap with identified animal health research needs. These include development of (1) alternatives/refinements for painful management procedures such as beak trimming and dehorning; (2) alternatives/refinements of euthanasia and slaughter methods to reduce pain and distress; (3) improvements in handling and transportation to reduce injury and distress; (4) new or modified production systems that provide animals with more behavioral
opportunities while maintaining good animal health and production; (5) genetic and management methods to reduce the incidence of musculoskeletal disorders (e.g., lameness and osteoporosis); (6) methods for dealing with nutritionally based problems, including nutritional deficiencies/imbalances and feed restriction; (7) new preventive and prophylactic strategies to maintain good animal health in alternative management systems, such as organic and antibiotic-free, that prohibit the use of current disease prevention or treatment methods; (8) outcome-based (i.e., health and behavior) welfare assessment criteria that can be measured noninvasively for on-farm assessment; and (9) management methods for young/neonatal animals to improve later stress-competence and adaptability. These research priorities should be elaborated on to encompass the areas of emphasis identified by the OIE (World Organization for Animal Health) as part of the general principles for animal welfare (Box 2-3). The need for more translational research is also becoming apparent due to the extent to which animal welfare research is being incorporated into codes of practice, industry standards, and regulation (Appleby, 2003; Mench, 2008). This is increasing the focus on on-farm studies and the use of epidemiological methods and modeling to assess the environmental and management factors that are risks for poor welfare outcomes in commercial flocks and herds (Dawkins et al., 2004; Butterworth et al., 2011).
Although the research priorities identified above focus mainly on food animals, there is also growing emphasis on and an increasing body of knowledge about the welfare of farmed fish (Branson, 2008). Active areas of research and continuing research need to include the effects of stressors (e.g., stocking density, water quality, conspecific aggression, transport, slaughter) on fish behavior and physiology and the development of handling and slaughter methods that reduce pain, injury, and distress (Conte, 2004; Huntingford et al., 2006; Ashley, 2007). Cognizance and application of management practices that reduce stress during rearing will correspondingly minimize the incidence of disease. One such method could be the development of feeds that have the target of reducing stress through the identification of the optimal amount and balance of nutrients in feeds. Simpson and Raubenheimer (1995) offered a geometric multidimensional framework strategy to identify optimal amounts and balance of nutrients for insects with a growth target in mind. This approach may have application to vertebrates and would most probably compromise some growth in the interest of the welfare of the organism during rearing.
Rising concern about animal welfare is a force shaping the future direction of animal agriculture production. Animal welfare research, underemphasized in the United States compared to Europe, has become a high-priority topic. Research capacity in the United States is not commensurate with respect to the level of stakeholder interest in this topic.
There is a need to build capacity and direct funding toward the high-priority animal welfare research areas identified by the committee. This research should be focused on current and emerging housing systems and management and production practices for food animals in the United States. The Foundation for Food and Agricultural Research, USDA AFRI, and USDA ARS should carry out an animal welfare research prioritization process that incorporates relevant stakeholders and focuses on identifying key commodity-specific, system-specific and basic research needs, as well as mechanisms for building capacity for this area of research.
3-9 Feed Safety
With the need to produce more protein for the projected human population in 2050, a variety of traditional and alternative animal feed commodities (feedstuffs) will be incorporated into feeds. In the United States, individual states regulate the contents of commercial animal feeds while the FDA regulates the content and manufacture of animal feed at the federal level. In particular, efforts are directed to eliminate the presence of unwanted contaminants that adversely affect the health of farmed species as well as the human consumer by passage through the food chain (Sapkota et al., 2007). These contaminants include polychlorinated biphenyls and other persistent organic pollutants (POPs), excessive levels of heavy metals (lead, mercury, cadmium, and chromium) or mineral salts (arsenic, selenium, and fluorine) (Reis et al., 2010), and pesticides. These contaminants are contained in either the feedstuffs or forage while others arise from external contamination during storage. For example, in 1997, the FDA found animal feeds contaminated with dioxin, which resulted in elevated levels of dioxin in chickens, eggs, and catfish due to bioaccumulation in fatty tissue
(Hayward et al., 1999). Dioxin is a polychlorinated aromatic hydrocarbon POP, which originated from a mined product termed “ball clay” that was used as an anticaking agent in the soybean meal feedstuff. Another example is elevated levels of selenium, which although it is a required micronutrient, acute or chronic consumption of forage or feed containing excessively high levels can result in an array of clinical symptoms that include lethargy, reduced feed consumption and growth, and a variety of pathologies (Zain, 2010).
As an importer of animal protein products, the United States must be involved in the development of international standards, guidelines, and recommendations that protect the health of farmed animals and consumers. For example, over 80 percent of all seafood consumed in the United States is imported; international standards are in the best interests of the United States. To ensure feed safety for both farmed animals and consumers, outreach, education and quality assurance programs need to be developed for feed manufacturing facilities. In developing countries, outreach and education will be critical to the successful transition from extensive to semi-intensive farming and will require complete or supplemental manufactured feeds as part of farming practices. The Codex Alimentarius Commission is responsible for codes of practice designed for the prevention and reduction of food and feed contamination (WHO and FAO, 2012) and should serve as the foundation for the development of international standards, guidelines, and recommendations to protect the health of farmed animals and consumers. Development of rigorous policies, regulations, and successful outreach programs combined with improved analytical methods are necessary to effectively detect contaminants both in the United States and internationally. Assurance of high-quality feeds is an important component of sustainable intensification by mitigating or eliminating the incidence of any potential adverse effect on the health and productivity of farmed animals and the health of consumers. This knowledge should be complemented by educational efforts to increase an understanding of the many poisonous plants that can be consumed by certain species of farmed agricultural animals, the conditions that might lead to consumption, and the resulting adverse effects on health.
Feed safety challenges include contaminants of microbial, chemical, and biological origin; as well as consideration of the safety of feed additives. Feed additives include technological additives such as preservatives, colors, antioxidants, emulsifiers, stabilizing agents, acidity regulators, and silage additives; as well as sensory and nutritional
additives, digestibility enhancers, medications, and gut flora stabilizers (EFSA, 2014). Typically, before companies commercialize these additives, they are evaluated for safety and efficacy. The FDA has established guidance documents for evaluation of food additives in diets fed to food animals (FDA, 2014b).
Inadvertent presence of feed contaminants can cause significant animal health risks, which may or may not translate to human health risks. FDA (2014a) regulates animal feed safety and has provided documents relevant to bovine spongiform encephalopathy (BSE), medicated feed in which the medications are additives that enhance nutritional concentrations in diets or are prophylactics against disease, and contaminants, including dioxin in anticaking agents and mycotoxins. In the context of sustainability, it is important to consider how future climate scenarios may affect the safety of animal feed. Perhaps the greatest concern in this regard is the risk of increased levels of mycotoxins in animal feed crops. Mycotoxins are secondary metabolites of foodborne fungi that have toxic effects on the animals and humans that consume them. For animal feed in industrial production systems, the mycotoxins of greatest concern are found in feeds based on corn, peanuts, and small cereals such as wheat, barley, and oats. The three most important groups of mycotoxins are aflatoxins, fumonisins, and deoxynivalenol (DON, “vomitoxin”) (Table 3-4).
The FDA has set multiple action levels for total allowable aflatoxin in feeds for different groups of animals (FDA, 1994). Likewise, it has industry guidelines for allowable fumonisins and DON in various animal feeds. Two recent concerns have emerged regarding levels of mycotoxins in animal feed. The first is the use in feed of distillers’ dried grains with solubles (DDGS), which are co-products of corn-based ethanol production. The ethanol production process concentrates the original mycotoxins in the corn up to three times in the DDGS, which are then sold for animal feed in the United States. Although animal feed is never composed entirely of DDGS, even adding it in the proportions suggested by animal nutritionists could lead to higher mycotoxin exposures that cause observable animal effects, such as reduced productivity (Wu and Munkvold, 2008). Additionally, in the near future, there is reason to believe that increased climate variability associated with climate change trends may result in higher preharvest levels of certain mycotoxins in crops, posing both economic and health risks (Wu et al., 2011). As the leading producer of corn in the world market, the United States must be well posed to address the potential impacts of climate change on corn for
animal feed in terms of economic losses from excessively high mycotoxin levels at grain elevators and in terms of animal health losses.
Implications for the future of U.S. food security from mycotoxins in animal feed are twofold. First, there is the direct toxicological concern of whether mycotoxins are bioavailable in animal products that humans consume. Although most mycotoxins do not bioaccumulate in meat, dairy animals that consume aflatoxin metabolize it to aflatoxin M1, which is then present in milk and other dairy products. Second, higher mycotoxin exposures in animal feed translate to reduced growth and productivity, which means economic loss to producers as well as reduced supplies of meat and animal products for human consumption. Hence, reducing mycotoxin levels in animal feed is critical for sustainable food animal industries to ensure future food security.
TABLE 3-4 Adverse Animal Health Effects Associated with Three Classes of Mycotoxins
|Mycotoxin||Fungi That Produce Toxins||Crops Contaminated by Toxins||Animal Health Effects|
|Aflatoxins||Aspergillus flavus, A. parasiticus||Corn, peanuts, tree nuts (almonds, pistachios, hazelnuts, etc.), copra, cottonseed, spices||Liver tumors Immune suppression, Reduced weight gain and productivity Lower eggshell quality in poultry|
|Fumonisins||Fusarium verticillioides, F. proliferatum, A. niger||Corn||Equine leukoencephalomalacia Porcine pulmonary edema Reduced weight gain and productivity|
|Deoxynivalenol (DON)||F. graminearum, F. culmorum||Corn, wheat, barley, oats||Gastrointestinal disorders Immune dysfunction Reduced weight gain and productivity|
SOURCE: Wu et al. (2011).
As an importer and exporter of animal protein products, the United States is affected by the development of international standards, guidelines, and recommendations that protect the health of the farmed species and the consumers through regulation of contaminants in feeds and feedstuffs. One research priority for this area includes:
- Research through U.S. agencies in the identification of feed and feedstuff contaminants should continue so that rigorous policies of regulation can continue to be updated to protect the health of farmed species and consumers and provide information to feed manufacturers through outreach programs.
3-10 Food Safety and Quality
3-10.1 Food Technology
Supplying affordable, safe, and desirable animal products as a source of nutrients to the human diet is important. Americans annually purchase about $100 billion of animal products (e.g., meat and meat products, poultry products, fish, shellfish, and dairy products, and nonfood products, such as wool, mohair, cashmere, and leather) at the farm gate and retail levels (USDA NIFA, 2009). The quality and safety of animal products prior to harvest are influenced by genetics, nutrition, and management systems, while after harvest they are affected by handling, processing, storage, and marketing practices (USDA NIFA, 2009). The threat from foodborne illness due to animal products has been reduced during the last few decades, particularly because of the improvement in the hygienic process of food (Morris, 2011). The hygienic process of animal origin food was mainly derived through a series of recommendations from several research initiatives conducted via experimental and observational studies of foodborne agents (e.g., bacterial, viral, and toxins). The practice of Hazard Analysis of Critical Control Points (HACCP) was initiated through research and is currently becoming the standard for food safety in the United States and abroad as many food-producing systems are adapting HACCP in their operations. One obstacle in overcoming foodborne illnesses is public fear and resistance to food safety techniques such as meat irradiation (Box 3-11).
Irradiating Meat to Combat Foodborne Illness
The Centers for Disease Control (CDC) estimates that one in six Americans (or 48 million people) become sick from foodborne illnesses each year (CDC, 2014). Developing an effective means of ensuring that meat products are safe for consumption is paramount. Irradiating meat products is one means of killing potential pathogens and sanitizing meat for consumers. The FDA approved the use of irradiation in 1963 for wheat and flour, and has since expanded its allowed use to include fruit, meat, vegetables, and spices (USDA FSIS, 2013). Academic studies in the following years confirmed the safety of irradiation as a food safety practice, also finding that the practice did not harm food properties such as nutritional value (Stevenson, 1994). Irradiation has the positive benefit of damaging the DNA of living organisms when used in high energy rays, which kills potential foodborne pathogens (Tauxe, 2001). The USDA Food Safety and Inspection Service (FSIS) noted in its final rule on meat and poultry irradiation that “irradiation of meat and poultry does not increase human exposure to radiation since the energy used is not strong enough to cause food to become radioactive,” adding that during testing scientists used higher levels of radiation than those approved for use and discovered no negative health effects from consuming the irradiated meat (USDA, 1999). But despite the scientific acceptance of irradiated meat’s safety, there are still difficulties in selling its safety to the public. As was documented in a survey by the Foodborne Diseases Active Surveillance Network, only half of surveyed adults were willing to purchase irradiated ground beef or chicken, and only a fourth of respondents were willing to pay a “premium” for these meats which (at the time of that survey) cost more to produce than nonirradiated products (Frenzen et al., 2000). Despite scientific consensus of the public health benefits from meat irradiation, the public acceptance of this practice faces an uphill battle.
A major goal of food safety is to determine a way to measure the impact of interventions at different phases of the production chain. Research is needed to examine individual interventions and those used in combination, and the economic considerations of such interventions. The continued identification and evaluation of risk factors is needed to understand the transmission and persistence of foodborne organisms, and the development and implementation of interventions, mitigation,
prevention, and/or control strategies are needed (Oliver et al., 2009). Research should target more rapid, sensitive, and specific diagnostic tests for many foodborne pathogens.
With the growing popularity of “organic” and “natural” food products and the number of recalls of products from these production systems, an increased emphasis on food safety is required, especially in microbial pathogen control. Research is needed to determine better and faster pathogen detection methods for laboratory and field application (Sofos, 2009). The concept of food quality has been evolving within the animal product industry to where there is (1) hygienic quality (i.e., absence of heavy metals, pesticides, mycotoxins, feed additives, drugs, pathogens, and microbial contaminants); (2) compositional quality (e.g., water, protein, fat, and ash); (3) nutritional quality (i.e., biological value of protein and fatty acid composition); (4) sensorial quality (e.g., taste, color, flavor, odor, tenderness, and juiciness); and (5) technological quality (i.e., suitability for processing, storage, and distribution) (Nardone and Valfrè, 1999). Hocquette et al. (2005) provided other definitions of quality; however, most experts make a distinction between intrinsic and extrinsic quality attributes. Intrinsic quality refers to safety and health aspects, sensory properties and shelf-life, chemical and nutritional attributes, and reliability and convenience of food. Extrinsic quality refers to production system characteristics and marketing variables such as traceability. The most important intrinsic quality traits include color, texture, flavor, juiciness, and healthiness, and the most important extrinsic trait is traceability (Hocquette et al., 2005). Traceability needs ongoing validation because it is a vital component of operational standards and certification programs. The implementation of traceability for aquaculture products is a work in progress that is confronted with many challenges (Schroder, 2008). Traceability systems are particularly pertinent to aquaculture products that are taking on increasing significance in global trade and are highly perishable. Product supply chains are monitored with the ultimate goal of guaranteeing an accurate determination of product sources to protect consumer health and prevent fraud (e.g., misrepresentation of species). A practical guide for traceability in the U.S. seafood industry has been produced (Petersen and Green, 2006).
There have been many advancements and innovations in animal product quality in the past 30 years (Aumaître, 1999; Nardone and Valfrè, 1999; Higgs, 2000; Hocquette et al., 2005, 2007; Goff and Griffiths, 2006; Henning et al., 2006; Sofos, 2009). Nardone and Valfrè
(1999) evaluated the effects of production methods and systems such as genetics, nutrition, management, and animal health on poultry meat, cattle meat, eggs, and milk quality. Genetics provides the greatest opportunity for improvement in quality, followed by nutrition and management. An example of the application of functional genomics on beef quality such as tenderness and marbling is provided by Hocquette et al. (2007). Research has also determined how quality attributes such as color, texture, tenderness, flavor, and juiciness can be altered (Hocquette et al., 2005). In the dairy industry, fluid milk processing has made technological advancements in extending the shelf life of milk by high-heat treatment, microfiltration, and aseptic packaging (Goff and Griffiths, 2006). Membrane filtration technology has been an important advancement in dairy processing in the past few decades for all dairy products, and cheese production has benefited from increased knowledge of the genetics of microorganisms used during their production (Henning et al., 2006; Johnson and Lucey, 2006). Red meat production has benefited from selective animal breeding and the increased trimming of fat, which has resulted in a decrease in the total fat and saturated fat content of red meat (Higgs, 2000).
In the future, animal product research in the United States needs to focus on the quality of animal food products. Genomics and proteomics are likely to be the most important factors in affecting animal product quality (Nardone and Valfrè, 1999; Hocquette et al., 2005; Johnson and Lucey, 2006). Animal nutrition research needs to further assess the sanitary and nutritional characteristics of meat (i.e., fatty acid composition such as conjugated linoleic acid and omega-3s, polyunsaturated fatty acids, vitamins and trace minerals, antioxidants, and chemical and technological characteristics of fat). The effect of different management systems on meat, milk, and egg quality will need further research with a focus on hygienic and organoleptic qualities Fundamental research is important to understand the biological and physical mechanisms, and to develop new techniques to improve quality. Sensory quality and methods using a systems approach to improve the nutritional value of fish, meat, milk, and eggs and associated products should remain a research priority (Hocquette et al., 2005).
The quality and safety of animal products prior to harvest are influenced most by genetics, nutrition, and management. Genetics provides the greatest opportunity for further improvement in animal product quality; although technological advances have played a major
role in milk and dairy food processing, genetics and nutrition have been the major contributors to beef, pork, and chicken quality. Traceability is an important component of the assurance of food quality and needs ongoing validation because it is also a vital component of operational standards and certification programs. Research priorities for this area include:
- Studies to identify and evaluate risk factors to understand the transmission and persistence of foodborne organisms should be initiated and conducted by relevant public institutions including universities. These studies should be aimed toward the development and implementation of interventions or mitigations across all the phases of the production chain. The validity of prevention or control strategies should continue to be assessed.
- More rapid, sensitive, and specific foodborne pathogen diagnostic assays need to be developed for laboratory and field application.
- Research should be conducted to understand the biological and physical mechanisms relevant to improving nutritional, functional, and organoleptic qualities of animal products.
3-10.2 Food Losses and Food Waste
Food is lost or wasted throughout the food chain (Figure 3-4). Food losses refer to qualitative (i.e., reduced nutrient value, undesirable taste, texture, color, and smell) and quantitative (i.e., weight and volume) reductions in the amount and value of food. Food losses represent the unconsumed edible portion of food available for human consumption. Food waste is a subset of food loss and generally refers to the deliberate discarding of food because of human action or inaction.
FIGURE 3-4 Areas of food losses and wastage. Illustration by Britt-Louise Andersson, Stockholm International Water Institute.
SOURCE: Lundqvist et al. (2008). Reprinted with permission from the Stockholm International Water Institute.
Food loss and waste are important for the following reasons (Buzby and Hyman, 2012): (1) food is needed to feed the growing population and those already in food insecure areas; (2) food waste represents a significant amount of money and resources; and (3) there are negative externalities (i.e., GHG emissions from cattle production, air pollution and soil erosion, and disposal of uneaten food) throughout the production of food that affect society and the environment. Annual global food loss and waste by quantity is estimated to be 30 percent of cereals; 40-50 percent of root crops, fruits, and vegetables; 20 percent of oilseed, meat, and dairy products; and 35 percent of fish (FAO, 2014a). One-third or 1.3 billion tons of the food produced for human consumption is lost or wasted globally (Gustavsson et al., 2011). In 2008, the estimated total value of food loss at the retail and consumer levels in the United States as purchased retail prices was $165.6 billion or 30 percent of the total value (Table 3-5; Buzby and Hyman, 2012). In terms of the value of food loss, meat, poultry, and fish accounted for 41 percent and dairy products for 14 percent of the total loss in food supply value (Buzby and Hyman, 2012).
TABLE 3-5 Estimated Total Value of Animal Product Loss at 2008 Retail and Consumer Levels in the United States
|Animal Product||Food Supply, Million $||Losses from Food Supply|
|Retail Level||Consumer Level||Total Retail and Consumer Level|
|Million $ %||$ Million %||Million $ %|
|Other dairy products||73,957||6,180||8||10,515||14||16,695||23|
|Meat, poultry, fish||176,284||8,453||5||59,844||34||68,297||39|
SOURCE: Adapted from Buzby and Hyman (2012).
The total food loss at the combined retail and consumer level in the United States was estimated to be 28 percent dairy products, 38 percent meat, 41 percent poultry, 33 percent fish and seafood, and 23 percent eggs (Buzby and Hyman, 2012). The major contributors to food loss at this level include spoilage, expired sell-by dates and confusion over label dates (NRDC, 2014), all of which pertain to shelf life. In the United Kingdom, 60.9 percent of the food wasted could be attributed to storage and management, which is directly linked to shelf life with smelling and tasting bad and past due dates as the major reasons for disposal (WRAP, 2008). One extra day of shelf life could result in savings of £2.2 billion due to less food waste in the United Kingdom (Robinson, 2014).
One major research focus for food loss in animal products is shelf life. Shelf life can be defined as the time it takes a food product to deteriorate to an unacceptable degree under specific storage, processing, and packaging conditions. Time to deteriorate depends on the product composition, storage conditions (e.g., temperature, atmosphere), processing conditions, distribution conditions, initial quality, and packaging. Modes of food deterioration include microbial, insects and rodents, chemical (i.e., oxidation, flavor deterioration, color change or loss, vitamin loss, enzymatic), and physical (i.e., moisture or textural change) (Hotchkiss, 2006). For aquaculture, technologies that can be effectively applied post-harvest are needed to extend shelf life.
Improving animal product shelf life would reduce wastage and open or expand export markets, and may make niche-oriented, lower-volume products more economical.
A lot of research has gone into extending the shelf life of dairy products. Dejmek (2013) provides a historical overview of milk shelf life including heat treatment, pasteurization, ohmic heating, and microwave and ultrahigh-temperature (UHT) sterilization. Post-pasteurization shelf life is affected by contamination of milk by psychrotrophic bacteria, presence of heat-stable enzymes (e.g., proteases and lipases), or presence of thermoduric psychrotrophs (e.g., bacterial spores that survive pasteurization) (Tong, 2009). With pasteurization and good storage temperatures, a 17- to 21-day shelf life can be attained. For extended shelf life, ultrahigh-temperature processes are used to sterilize all milk contact surfaces and disinfect packaging to prevent environmental contamination at filling. Shelf life for UHT milk may last 30 to 90 days in refrigerated storage. Bacterial growth is usually not an issue, but physical and chemical changes due to heating and prolonged storage can be major contributors to food loss (Tong, 2009). Research has found that storing milk at low refrigerated temperatures will reduce the rate of these changes affecting milk quality. Nonthermal technologies are being evaluated, such as pulsed electric field, high-pressure processing, membrane filtration, controlled-atmosphere packaging, and natural microbial inhibitors.
Extending the shelf life of eggs is another area of investigation. Eggs cooled under current methods lose AA grade (highest grade for eggs) in 6 weeks. If eggs could maintain AA grade for 8 weeks, then they could be shipped anywhere in the world. Scientists at Purdue University have discovered a rapid cooling technology that provides 12 weeks of AA grade rating (Wallheimer, 2012). Research efforts continue in the extension of meat shelf life. Major contributors to meat waste include off-color in the retail case and rancidity caused by oxidation, microbial contamination, and microbial load. Consumers in the United States prefer red meat to be red in appearance. The red color is the result of myoglobin in the meat binding to oxygen and iron (ferrous form) and converting it into oxymyoglobin. Over time, the oxymyoglobin is converted to metmyoglobin, due to oxidation, resulting in the meat changing color to brown, which is unappealing to consumers. In an effort to extend the shelf life and keep the appearance of the meat red longer, cattle feeders can feed a high level of Vitamin E (antioxidant) to animals. The Vitamin E deposited in the muscle tissue by the animal results in an
antioxidant effect, thereby slowing the color change in meat. Currently, cattle producers have not widely adopted the practice because the economic benefit to the retailer has not been passed back to the producers who must increase production costs to use Vitamin E.
Microbial load on or in meat can reduce shelf life and potentially cause human safety concerns, resulting in massive recalls and waste. Irradiation technology was developed to mitigate this problem. Pasteurization technologies such as irradiation, freezing, flash pasteurization, and ultrahigh-pressure exposure have been successfully used to inactivate pathogenic enteric viruses such as Vibrio in mollusks (Richards et al., 2010). New products and concepts to address the microbial load and contamination, including edible antimicrobial films being placed on the surface of meats to extend shelf life, are being explored (Morsy et al., 2014). Packaging technologies are also being researched to help extend meat shelf life. The goal of packaging is to reduce the rate of quality loss and extend shelf life. Recent technologies to extend shelf life include modified-atmosphere packaging (MAP), vacuum-skin containers, higher-barrier packaging, direct addition of carbon dioxide to products, broader use of irradiation, high pressure, ohmic heating, and pulsed-light treatment (Hotchkiss, 2006; Spinner, 2014). MAP is a packaging technology advancement that includes directly adding carbon dioxide (CO2 pad technology) to the package to displace oxygen and ethylene, which prevents the growth of aerobic bacteria. In February 2011, FDA granted approval for a CO2 pad technology to be used for meat, poultry, seafood, and fruit and vegetables, which is now in commercial use (JS Food Brokers, 2014). In addition, antimicrobial packaging is being investigated where the packaging material contains antimicrobial or bioactive materials, selective and adjusting barriers, indicating and sensing materials, and/or flavor-maintenance and -enhancing materials (Hotchkiss, 2006).
Research efforts need to continue to reduce animal product waste in the United States. Dejmek (2013) outlined the following areas to be further explored for dairy products: (1) sterile extraction of milk and the maintenance of carbon dioxide/oxygen status of raw milk; (2) a more complete understanding of the biology of spore germination, which would lead to new methods of reliably inducing germination and thus removing the need for sporicidal treatments; (3) affinity-based separations of pathogens and product spoiling enzymes; (4) a better understanding of the casein micelle to make it possible to manipulate the micelle size on the technical scale and thereby improve the efficiency of
bacteria separating methods; and (5) improvement of centrifugation efficiency by detailed computational fluid dynamics simulations of centrifuge flow patterns, which are now feasible. Research to extend fish, meat, milk, and egg shelf life and mitigate and prevent microbial contamination at the point of animal product harvest and packaging should be pursued. Research is also needed into how to better communicate the benefits and safety of technologies such as irradiation, which have been met in the past by consumer resistance.
3-11 Environment and Climate Change
Sustainability encompasses economic, environmental, and social considerations; however, sustainability is often assumed to address only environmental issues. At its core, animal agriculture is about converting natural resources of lower human value (e.g., forages and grains) to food and fiber products of higher value to humans (e.g., meat, milk, eggs, and wool). Although agriculture is essential for human civilization, it can also contribute to environmental degradation and change, natural resource depletion, and biodiversity loss. Animal agricultural productivity is also impacted by environmental change and climate variability. Incorporating sustainability into animal agriculture is challenging because it requires balancing increased global demand for animal products, mitigating environmental impacts, and addressing social concerns about animal welfare, food safety, and labor issues while also keeping food production economical for producers and consumers.
3-11.1 Implications of Historical U.S. Animal Agricultural Trends
In many cases, the changes in production efficiency that have been made across species in animal agriculture as previously discussed translate into reduced environmental emissions and resource use per unit of output (Table 3-6). Increased daily body-weight gains, daily milk yields, reproductive performance (e.g., eggs/hen per year), and shortened times to slaughter have all had a net effect of decreasing the amount of resources required for animal maintenance relative to animal production on an individual animal and a herd/flock basis (Capper and Bauman, 2013).
TABLE 3-6 Published Historical Comparisons of U.S. Egg, Dairy, and Beef Industries’ Environmental Impacts and Resource Use
|Reference||Industry||Years Compared||Change Relative to Historical Year|
|Pelletier et al. (2014)||Egg||1960 vs. 2010||65% lower acidifying emissions, 71% lower eutrophying emissions, 71% lower GHG emissions, and 31% lower cumulative energy demand per kilogram of eggs produced|
|Capper et al. (2009)||Dairy||1944 vs. 2007||79% fewer animals, 77% fewer feedstuffs, 65% less water, 90% less land, and 63% lower carbon footprint per 1 billion kg of milk produced|
|Capper (2011b)||Beef||1977 vs. 2007||30% fewer animals, 19% fewer feedstuffs, 12% less water, 33% less land, and 16% lower carbon footprint per 1 billion kg of beef produced|
Concomitantly with increased production efficiency, there has also been tremendous intensification and geographical concentration of U.S. terrestrial animal operations over the last several decades. Across all major U.S. animal agricultural industries, there has been a consistent trend toward decreasing the number of operations and increasing animal numbers per operation; however, total U.S. animal populations for the ruminant industries have greatly declined from historic highs (Figure 3-5).
The concentration and confinement of animals in one geographical location have increased public concern about how nutrients (particularly manure nutrients) are managed and lost to the environment and about human and animal health and welfare (Fraser et al., 2001; Donham et al., 2007). One notable exception to the concentration trend is the cow-calf and stocker/backgrounder phases of the U.S. beef industry. More cow-calf production now occurs from larger herds; however, there are still over 700,000 cow-calf producers in the United States with an average herd size of 40 beef cows (USDA Census of Agriculture, 2012b).
Additionally, both of these phases of the beef production chain rely heavily on extensive grazing of pasture and rangeland; therefore, there are inherent limits to the degree of consolidation that can occur in these sectors when extensive production practices are used.
Although improvements in production efficiency have largely reduced environmental impacts and resource use across animal industries per unit of output in the United States, there are nutrient concentration or resource supply challenges that are affecting and are affected by animal production. One example is water use in the western United States. California is currently experiencing a severe drought, which is highlighting the challenges of allocating water to municipalities, agriculture, and ecosystems within the state (Howitt et al., 2014). Another example is the High Plains Aquifer (or Ogallala), which extends from western Texas and eastern New Mexico to South Dakota and has dropped precipitously in certain areas, especially in the aquifer’s southern portion (USGS, 2014). The area’s economy is highly dependent on agriculture, and the region produces significant amounts of dairy, beef, and pork. The long-term viability of those industries in their current state may be impossible if the drop in the aquifer continues at its current rate (Steward et al., 2013). Water for animal feedstuff production contributes to 98 percent of the water footprint of animal products (Hoekstra, 2012). Research into improved water use, improved cropping systems (e.g., using lower-water-use crops and cover cropping), and better understanding of the social components of water use in the region (e.g., public policy) will be critical for the continued existence of animal agriculture in the region.
FIGURE 3-5 Distribution of 21.9 million dairy cows and heifers in 1939 (Top) and distribution of 9.3 million dairy cows in 2012 (Bottom).
SOURCES: USDA ESMIS (2012); USDA Census of Agriculture (2012a).
Clearly, these challenges to resource use and allocation extend far beyond the traditional boundaries of animal science research; however, incorporation of other sciences into a transdisciplinary approach will be necessary to manage such sustainability challenges related to animal production. As a result of increasing public concern and environmental regulatory measures, the past few decades have resulted in an increased focus on research, extension, and education of the environmental management of terrestrial animal agriculture. Efforts have been focused primarily on the impacts of animal agriculture on water quality; however, there has been an increasing interest in the impacts of animal agriculture on air quality and climate change.
Animal agriculture is a major consumer of surface and groundwater resources, with 98 percent of the water footprint of animal agriculture due to the production of feedstuffs for food animals. One research priority in this area includes:
- Research to increase the water-use efficiency of animal agricultural systems (including feed production) is necessary (e.g., better irrigation, water recycling, identifying animals that are more water-use efficient); however, such research should also consider the complicated issues of water resource allocation in areas of stressed freshwater availability.
3-11.2 Climate Change and Variability
Adaptation and building resilience to climate variability and change in animal agricultural systems will be a major challenge in the coming decades. Climate change will likely affect feed-grain production, availability, and price; pasture and forage crop production and quality; animal health, growth, and reproduction; and disease and pest distributions (Walthall et al., 2012). Increasing concentrations of carbon dioxide and certain impacts of climate change may also have beneficial implications for animal agriculture. Increasing atmospheric carbon dioxide concentrations may have a positive effect on the yields of plant species important for animal agriculture, particularly those with C3 photosynthetic pathways (e.g., wheat, barley, and soybeans; Wheeler and Reynolds, 2013). However, plants that use the C4 photosynthetic pathway have much less of a yield gain than C3 plants (Wheeler and Reynolds, 2013). For both C3 and C4 plants, water-use efficiency is
improved in conditions of higher carbon dioxide concentration (Drake et al., 1997).
Benefits of increasing carbon dioxide concentration on plant growth may be mediated by other environmental changes due to climate change, such as soil water availability (Polley et al., 2013). Increased variability in temperatures and precipitation will likely lead to decreased feed quality and increased environmental and nutritional stress for some animal agricultural species (Craine et al., 2010; Nardone et al., 2010; Wheeler and Reynolds, 2013). For example, an investigation of 76 years of growth records for Hereford beef cattle in the Northern Great Plains revealed that calf growth was greater in longer, cooler growing seasons, suggesting that increased temperatures decrease calf growth in the region (MacNeil and Vermeire, 2012). Heat stress already has a significant impact on the dairy, beef, swine, and poultry industries in the United States, with estimated annual economic costs at $1.69 billion to $2.36 billion due to decreased growth, reproductive performance, and lactation performance (St-Pierre et al., 2003). The prospect of more frequent heatwaves and higher average temperatures in the coming decades emphasizes the need for creating animal agricultural systems that are more adaptable and resilient to increased thermal stress.
As with terrestrial animal agriculture, climate change and variability will likely have both positive and negative effects on aquaculture. The United States currently imports 85 percent of its fish and shellfish; therefore, the impacts of climate change in major aquaculture regions such as Southeast Asia can have a significant impact on the ability to sustainably meet U.S. demand (Hatfield et al., 2014). Adaption and mitigation of the detrimental effects will be in response to changes in sea level and sea temperatures. Increases in sea level will eliminate or require the movement of existing coastal ponds, and increases in sea temperature will also affect growth of species cultured in cages, possibly increasing the incidence of disease. Oceans are absorbing approximately 25 percent of the CO2 emitted into the atmosphere, which is reducing oceanic pH (acidification), and ultimately affecting the physiology of species such that their presence and/or productivity would be reduced (Walsh et al., 2014). Temperature changes in the water can affect the direction of currents and changes in the wind magnitude and direction. These changes may ultimately compel an adaptive response founded in the need to relocate offshore operations. The prospects of expansion of the aquaculture enterprise along the coasts of the marine environment will frustrate continued development. Policy decisions will have to be
directed toward actions whereby mitigation and adaptation can be successfully implemented without compromising production. Because 65 percent of current aquaculture production is inland, mitigation activities for these freshwater production activities may be on a lower scale of magnitude than marine production activities (De Silva and Soto, 2009). One major concern is the lack of sufficient water resources; however, other concerns are water stratification in ponds or changes in disease-causing microbial flora.
Heffernan et al. (2012) offered the following recommendations to address the effects of climate change on animal infectious diseases. There is a need for frameworks and/or approaches that support collective learning and approaches within this emerging field. There is a need to enhance our abilities in predictive decision making. Critical areas that were identified as gaps include: (1) a greater understanding of the role of extra-climate factors on animal health, such as management issues and socioeconomic factors, and how these interplay with climate change impacts; (2) a greater cross-fertilization across topics/disciplines and methods within and between the field of animal health and allied subjects; (3) a stronger evidence base via the increased collection of empirical data in order to inform both scenario planning and future predictions regarding animal health and climate change; and (4) the need for new and improved methods to both elucidate uncertainty and explicate the direct and indirect causal relationships between climate change and animal infections.
Research will be needed to address the effects of climate change on crop productivity (Wheeler and Reynolds, 2013) and crop nutrient content. Bloom et al. (2014) reported a decrease of 8 percent in protein concentration in wheat, barley, rice, and potatoes with higher atmospheric carbon dioxide levels. Climate change effects on infectious diseases (Heffernan et al., 2012; Sundström et al., 2014) and animal production (Sundström et al., 2014) also need more research. Walthall et al. (2012) suggested research into technologies that improve management of agricultural products through automation of processes and tools, sensor development, and enhancement of information technologies.
The impacts of climate change and variability outlined above will have negative consequences for the efficiency of animal production and, thus, the environmental impact per unit of production. Consequently, adaptation to climate change and the mitigation of GHG emissions (and other environmental emissions) are intertwined, and future research
should increase the understanding of the impact of animal agriculture on the environment and the impact of the environment on animal agriculture rather than researching these relationships in isolation.
While there is uncertainty regarding the degree and geographical variability, climate change will nonetheless impact animal agriculture in ways as diverse as affecting feed quality and quantity and causing environmental stress in agricultural animals. Animal agriculture affects and is affected by these changes, in some cases significantly, and must adapt to them in order to provide the quantity and affordability of animal protein expected by society. This adaptation, in turn, has important implications for sustainable production. The committee finds that adaptive strategies will be a critical component of promoting the resilience of U.S. animal agriculture in confronting climate change and variability.
Research needs to be devoted to the development of geographically appropriate climate change adaptive strategies and their effect on GHG emissions and pollutants involving biogeochemical cycling, such as that of carbon and nitrogen, from animal agriculture because adaptation and mitigation are often interrelated and should not be independently considered. Additional empirical research quantifying GHG emissions sources from animal agriculture should be conducted to fill current knowledge gaps, improve the accuracy of emissions inventories, and be useful for improving and developing mathematical models predicting GHG emissions from animal agriculture.
Other Research Priorities
The committee supports previous recommendations by others that animal science research should increase the understanding of the impacts of climate change and variability on animal health and disease, animal productivity and welfare, and crop yields, quality, and availability. One research priority in this area includes:
- Research should develop viable climate change adaptation strategies for animal agriculture systems, including the development of information technologies to enhance animal agriculturalist decision making at the farm and operation levels.
3-11.3 Greenhouse Gas Emissions
In animal agricultural production, the GHGs that have received the most attention are nitrous oxide and methane. Carbon dioxide emissions result from the production of animal protein via the burning of fossil fuels throughout the supply chain and from soil in cropping systems. Respiratory carbon dioxide emissions from animals typically are not considered a net source of GHG emissions because the respiratory carbon dioxide is assumed to be offset by the carbon dioxide sequestered by the plants that animals consume (Steinfeld et al., 2006). Researchers, however, have evaluated GHG emissions from animal agricultural systems by accounting for carbon dioxide sequestered by plants and also respired by animals (Stackhouse-Lawson et al., 2012). Other GHG emissions from the production of animal protein include high-global-warming-potential refrigerants that can leak to the environment from the transportation and retail sectors of the supply chain (Thoma et al., 2013).
Nitrous oxide emissions from animal production typically result from soils applied with manure (i.e., deposited by grazing animals, deposited in open dry-lot facilities, or applied to pasture or cropland as a fertilizer source) or synthetic nitrogen fertilizers due to denitrification processes carried out by anaerobic bacteria (Robertson et al., 2013). Nitrous oxide emissions can also occur from manure storage systems, although total emissions from manure storage systems tend to be much lower than nitrous oxide emissions from manure-amended soils (EPA, 2014). This is due to the required nitrification transformation of manure ammonium to nitrate often being inhibited by the anaerobic nature of many manure storage systems in intensive U.S. animal operations (Montes et al., 2013). Although there is current and past research quantifying and investigating nitrous oxide emissions mitigation strategies, further collaborative efforts across crop and soil science, engineering and animal science disciplines will be needed to make significant improvements in emissions reductions. A particular emphasis should be placed on knowledge transfer of cost-effective mitigation strategies to animal agricultural producers. Furthermore, there is currently very little research on nitrous oxide emissions and mitigation opportunities in aquaculture systems, which is the fastest growing segment of animal agriculture; therefore, better understanding nitrous oxide emissions from aquaculture systems will be critical in coming decades (Hu et al., 2012).
Methane emissions can occur in anaerobic environments, such as manure storage systems and the foregut of ruminants. In 2012, enteric
fermentation was estimated to account for 24.9 percent of U.S. methane emissions and 23 percent of GHG emissions from agriculture in CO2 equivalents (EPA, 2014). Emissions of methane from manure management were estimated to be 9.3 percent of total U.S. methane emissions and 8.6 percent of GHG emissions from agriculture (EPA, 2014). The vast majority of methane emissions from enteric fermentation result from ruminant species (e.g., cattle, goats, and sheep); methane emissions from the digestive tracts of nonruminant herbivores and omnivorous species (e.g., pigs, poultry, and horses) are relatively minor (Crutzen et al., 1986). Methane emissions from ruminants generally increase with increasing feed intake and are affected by the type of carbohydrate and lipid content of the diet, feed processing, feed additives, or other strategies that can alter rumen microbial populations (Johnson and Johnson, 1995). Under strict anaerobic conditions, prokaryotic archaea primarily reduce carbon dioxide with hydrogen gas to generate energy for their own life processes and, as a consequence, produce methane, most of which is eructated out of the ruminant animal’s mouth (Ellis et al., 2008). Mitigation options for enteric methane emissions typically focus on inhibiting the archaea directly or reducing the amount of hydrogen gas available for methane production (i.e., methanogenesis). Mitigation options include the use of compounds that directly inhibit methanogenesis, alternative hydrogen gas sinks, ionophores, plant bioactive compounds, exogenous enzymes, direct-fed microbials, defaunation, manipulation of rumen archaea and bacteria, dietary lipids, forage quality, forage-to-concentrate ratio of the diet, feed processing, and precision feeding (Hristov et al., 2013). For many of the above-listed enteric methane emission techniques, more data from live animal experiments and long-term experiments are needed to determine their long-term efficacy (Hristov et al., 2013); however, collecting such data can be expensive due to the equipment and labor requirements involved. For U.S. ruminant systems, there is a dearth of data from grazing ruminant emissions because of the methodological challenges of measuring enteric methane emissions while allowing animals to graze. Additionally, increased consideration should be given to the cost-effectiveness of enteric methane mitigation strategies and the potential tradeoffs and unintended consequences of mitigating enteric methane emissions on other aspects of animal agricultural sustainability.
Methane from manure is typically emitted from liquid or slurry manure storage systems, with very little methane produced once manure is applied to land (Montes et al., 2013). Methane mitigation options from
manure storage typically focus on either preventing anaerobic conditions in storage systems, or, if anaerobic conditions exist, capturing or transforming methane through a flare to oxidize methane to carbon dioxide (Montes et al., 2013). Recent developments in new manure management and treatment systems include anaerobic digestion, which has the potential to decrease odor and pathogen loads. Anaerobic digestion also reduces nitrous oxide emissions from the land application of digested manure and is a source of energy from the biogas produced (Holm-Nielsen et al., 2009; Montes et al., 2013). Currently, installing and operating anaerobic digestion systems on animal operations is fairly cost-prohibitive, which has limited its adoption by animal agricultural operations despite the potential to improve environmental sustainability. A recently released report, Climate Action Plan—Strategy to Reduce Methane Emissions (White House, 2014) highlighted the importance of manure management and treatment technologies, such as anaerobic digestion, in mitigating methane emissions and strengthening the nation’s bioeconomy. Additionally, the report announced the partnership of the U.S. Environmental Protection Agency, Department of Energy, and USDA with the Innovation Center for U.S. Dairy to form a “Biogas Roadmap” to outline strategies to increase the adoption of anaerobic digesters. Furthering interdisciplinary research and engagement with stakeholders and policy makers is necessary to improve the economic viability of anaerobic digesters and increase their adoption.
Another incentive to develop cost-effective anaerobic digestive systems for animal agriculture is to “close the loop” and use food waste and other organic matter as feedstock for the anaerobic processes (Holm-Nielsen et al., 2009). With such systems, products previously considered waste with no human value and an environmental burden can be converted into valuable products and energy. Food waste at the retail, consumer, and food service portions of the animal agricultural supply chain are estimated to range from 16 percent of edible food for red meat, poultry, fish, and seafood to 32 percent of edible food for dairy products (Kantor et al., 1997). Waste-to-worth type of energy production systems can make animal production more sustainable and potentially avoid “food vs. fuel” dilemmas that occur with other biofuels, such as corn-derived ethanol.
There are uncertainties associated with current GHG emission predictions; however, ruminant (cattle) meat production systems tend to
have higher GHG emission intensities compared to monogastric (swine, poultry, fish) production systems. Dual-purpose ruminant systems (e.g., milk production) tend to have lower GHG emission intensities than ruminant meat production systems. GHG emission mitigation strategies can offer considerable synergies with other desirable outcomes (e.g., reducing methane emissions from ruminants can increase feed energy conversion efficiency, and anaerobic digestion of animal manure can lead to the generation of renewable energy). However, research testing GHG emissions mitigation strategies has often been conducted without consideration of economic and social sustainability concerns. Research priorities for this area include:
- Research investigating GHG emission mitigation strategies should consider the impacts of such mitigation strategies on other environmental pollutants (e.g., ammonia emissions), as well as the economic and social viability of such mitigation strategies. Whole farm systems and whole-food supply-chain systems-based evaluations of the effects of mitigation strategies are needed.
- Research should build on the potential value of anaerobic digestion of animal manure and other organic wastes as well as other approaches that help to close energy and nutrient loops in the food system.
3-11.4 Air Quality and Nuisance Issues
The concentration of animal production has shifted how animal manure and litter are managed. While animals in extensive systems will deposit their urine and feces while grazing or foraging, manure or litter in confinement systems must be collected and usually stored in some way. While anaerobically stored manure can be a source of methane emissions, fresh animal manure and litter in animal housing systems can be a source of ammonia emissions when applied to land. Ammonia emissions occur when manure is exposed to air and can be affected by pH, temperature, and wind speed (Robertson et al., 2013). Past research has investigated optimizing nitrogen use in animal diets, and improved manure management techniques that can reduce ammonia emissions. It has been estimated by the EPA (2014) that 54 percent of ammonia emissions come from animal waste. Emissions of ammonia from animal agricultural operations can contribute to human respiratory health problems, acidification of environments, and eutrophication of water bodies (Aneja et al., 2001; Pinder et al., 2007). Although these emissions are currently unregulated, U.S. regulation in the next 40 years is likely;
therefore, further research, extension, and education efforts into increasing nitrogen-use efficiency and ammonia emission mitigation techniques from animal agricultural systems should be a priority to ensure science-based policy approaches and to provide viable mitigation options to animal agriculturalists.
Additionally, animal agriculture can contribute to the formation of tropospheric ozone through the emissions of volatile organic compounds and methane. Tropospheric ozone can both directly and through the formation of secondary aerosol particles lead to negative human health outcomes and decrease the net primary productivity of ecosystems and agricultural systems (Lippmann, 1991; Ainsworth et al., 2012; Shindell et al., 2012). Methane emissions from animal agriculture are typically not thought of as a local driver of ozone formation within airsheds, but rather contribute to the continued increase in global background tropospheric ozone concentrations (Fiore et al., 2002). As a consequence, research that identifies viable methane emission mitigation strategies can reduce animal agriculture’s contributions to both climate change and reduced air quality. Recent research has found that most volatile organic compounds are emitted from fermented feed sources rather than fresh and stored manure sources (Howard et al., 2010a,b). Mitigation strategies that reduce emissions from fermented feed also have the potential to reduce feed losses, which is beneficial to animal agricultural producers (Place and Mitloehner, 2014). More research is needed to better characterize emission sources from animal agriculture that lead to reduced air quality, to develop economically viable mitigation strategies for animal agricultural producers, and to understand the relationships and tradeoffs of mitigation strategies with other aspects of sustainability.
Odor is a continual issue with animal agriculture in the United States, particularly in areas where suburban encroachment results in people previously unexposed to animal agriculture living in close proximity to animal farms. Research on characterizing and mitigating odor from animal operations has been ongoing for the past few decades; however, an improved understanding of the compounds that cause odor from animal operations and measurement technologies is required (Rappert and Müller, 2005). Additionally, pests, such as flies and rodents, can increase due to animal waste (e.g., feces and urine) and feedstuffs on animal operations, which can be another point of conflict with nonagricultural neighbors close to animal agricultural operations. Additionally, these pests can spread disease (CDC, 2014). With the increased trend toward intensification both in the United States and
globally, it is likely that there will be more conflicts within communities between the general public and animal agricultural producers. Research can help with these conflicts both by providing more technical knowledge of odor mitigation and improving the communication between these two groups.
3-11.5 Nutrient Management
Most animal manure is applied to cropland, which can be beneficial as a source of nutrients and organic matter for soil, but can also be a source of groundwater and surface-water pollution. Animal agriculture can be a significant source of groundwater nitrates in areas of concentrated animal agriculture (Harter et al., 2012). Animal agriculture is a non-point source of nitrogen and phosphorus that contributes to algal blooms and subsequent dead zones in water bodies such as the Chesapeake Bay and Gulf of Mexico (Diaz and Rosenberg, 2008). As food animal operations have grown larger, the EPA and corresponding state agencies have developed regulations for animal feeding operations (AFOs) and concentrated animal feeding operations (CAFOs). These regulations have historically focused on the impact of terrestrial animal operations on water quality; however, some states, such as California, have moved toward permitting facilities for air emissions as well. In response, animal science and affiliated departments (e.g., crop and soil sciences) at land-grant universities have conducted research to address manure nutrient management and to reduce nutrient excretion from animal operations to the environment.
A criticism of CAFOs is that animal and crop systems have become decoupled, leading to the concentration of manure nutrients within relatively small geographical areas (Naylor et al., 2005). Previous integrated crop and animal agricultural production system research has demonstrated benefits of such systems, including increased biodiversity and better water quality and soil carbon sequestration, and nutrient cycling when compared to crop systems that do not integrate food animal production (Tomich et al., 2011; Barsotti et al., 2013; George et al., 2013). Examples of integrated crop-animal production systems include grazing ruminants on grain corn residue in the Corn Belt of the United States, dual-purpose wheat pasture systems in the southern Great Plains, agroforestry and silvopasture systems in the southeastern and western United States, and sod-based crop rotations (Sulc and Franzluebbers, 2014), as well as integrated terrestrial and aquatic systems (Godfray et al., 2010). Despite these examples, separate and specialized crop and
animal production systems have become conventional in the United States (Sulc and Franzluebbers, 2014). Further basic and applied research on integrated crop and animal systems, including research into understanding the barriers and limitations of their adoption by agricultural producers would improve our understanding of ways to mitigate the undesirable environmental effects of the concentration of animal operations.
Nutrients are necessary for crop production systems, and integrated animal-crop systems can enhance nutrient cycling; however, concentrated manure nutrients, if improperly managed, can also lead to environmental pollution caused by nutrient runoff and leaching. One research priority in this area includes:
- Continue and enhance research on the nutrient management of animal agricultural systems. Research should be directed to assessment of current and novel integrated crop-animal production systems, as well as the potential barriers and limitations to their adoption by agricultural producers.
3-11.6 Systems Evaluation: Environmental Metrics and Life-Cycle Assessment
A key challenge with sustainability is measurement and determining key indicators or metrics of sustainability in animal agriculture. When considering environmental impacts and, in particular, GHG emissions, recent research has focused on quantifying and mitigating environmental emissions per unit of output (e.g., per kilogram of product or protein) rather than per animal or per unit of land. The rationale for expressing environmental impacts per unit of output (known as the “functional unit” in life-cycle assessment [LCA]) is to report impacts on the basis of the animal production system’s value to humans (de Vries and de Boer, 2010). Expressing impacts per unit of land can be problematic due to variations in soil types and climate, while expressing impacts per animal creates difficulties for comparisons across animal breeds and species. The efficiency of calorie production per hectare has been analyzed and animal production has been shown to be less efficient than crop production, with beef and other ruminant production being the least efficient (Cassidy et al., 2013; Eshel et al., 2014). The aquaculture enterprise is recognized as having the least adverse environmental impact of any animal production system. When compared to other animal
protein production systems (beef, chicken, or pork), aquaculture is the most efficient and environmentally friendly as manifested in feed conversion, protein efficiency, nitrogen emissions, phosphorus emissions and land use (Bouman et al., 2013). For example, average nitrogen and phosphorus emissions for fish are 2.5 to 3.0 times lower than emissions for beef and pork at equivalent levels of protein production. However, others have suggested that when comparing ruminant efficiency to other species, the conversion of human edible or digestible energy and protein should be considered, rather than simply kilograms of feed or calories to produce a kilogram of beef or milk (Oltjen and Beckett, 1996; Wilkinson, 2011; Eshel et al., 2014). The proper functional unit of any one environmental analysis of animal production systems will depend on the goals of the analysis and should take into account that there are often multiple outputs of value from animal production systems (e.g., meat, milk, leather, and manure, which can have fertilizer value, are all outputs from dairy production). Transparency and clearly delineating assumptions are crucial for any environmental assessment of an animal agricultural production system. When evaluating environmental impacts from animal agricultural production, LCA is often used (Box 3-12). Different species and production systems have been evaluated in recent LCAs, including aquaculture (Cao et al., 2013), poultry (Pelletier, 2008; Pelletier et al., 2014), swine (Pelletier et al., 2010a; Thoma et al., 2011), beef (Pelletier et al., 2010b; Capper, 2011a; Lupo et al., 2013) and dairy (Capper et al., 2009; Thoma et al., 2013).
Life-Cycle Assessment and Application to Animal Agricultural Production
LCA has been often applied in studying and evaluating the environmental impact related to the production of meat and other agricultural products. A technique that is intended to measure a product’s environmental impact throughout all stages of its life (cradle to grave) (Curran et al., 2005), LCA is often employed in analyses of production processes. There are four main components to any LCA analysis: (1) goal defining and scoping, where the objective and limitations/boundaries of the analysis are established; (2) inventory analysis, where the use of inputs and environmental releases is recorded; (3) impact assessment; and (4) interpretation (SAIC, 2006). These steps account for the environmental impact generated within the defined scope of the
system for a specific quantity of a manufactured product. LCA has been applied in studying the environmental impact of pork, lamb, and beef, as well as related products such as dairy and leather (Peters et al., 2010). Although LCAs can provide valuable insights into the environmental intensity of meat production, they are also very much subject to the assumptions made in terms of the scope of study. Additionally, it has been noted that LCA is “a continuously evolving science, and the studies produced are time-point, market, and region specific. It is therefore difficult to compare across studies with any degree of certainty” (Capper and Hayes, 2012). Additionally, many LCAs use prediction models to estimate the environmental emissions from animal agriculture that are empirical and derived from site-specific data. Increasing the use of processed-based simulation models to derive estimates of emissions, such as methane and nitrous oxide, could reduce the error associated with LCA results (Rotz and Veith, 2013). While there is definite room for improvement in terms of standardization and comparing the results from LCA studies, it still remains a valuable tool used in the environmental study of production processes.
Adapted from its original use in evaluating industrial processes, LCA is essentially an environmental accounting system that sums impacts of interest across the entire production chain, from cradle to grave. For animal agriculture, this can include impacts from crop production, animals and their manure, processing, and transportation. Few LCA of animal agricultural products have conducted full cradle-to-grave assessments, but have instead focused on impacts generated at the farm gate with varying scopes and geographical locations assessed. Variation in scope and scale across LCA is a key challenge for making comparisons across published estimates. In an attempt to harmonize LCA methodological differences, the Livestock Environmental Assessment and Performance Partnership (LEAP), a collaborative effort of stakeholders from governments, nongovernmental organizations, and the private sector released draft guidelines regarding LCA for feed supply chains, small ruminants, and poultry production in early 2014 with plans to release guidelines for large ruminants in the near future.
Life-cycle assessment allows for evaluation of the impacts from the full production chain of a given animal production system, which can better account for the potential unintended consequences of changing one aspect of the production chain on the other phases of production. Additionally, consequence-related LCA techniques could be used to
understand the environmental and economic tradeoffs associated with alternative uses of the biomass fed to animals (e.g., forages, byproducts, and grains), such as the production of biofuels or human food.
Quantifying uncertainty in LCAs is yet another challenge. Enteric methane emissions, for example, are not easily measured; therefore, LCAs rely on prediction equations to estimate methane emissions produced by ruminants via enteric fermentation. However, the accuracy of such models is fairly poor (Moraes et al., 2014), and there is a severe lack of empirical methane emissions data from grazing cattle. Remedying this uncertainty in enteric methane emissions should be a priority if there is interest in better understanding the formation of enteric methane emissions and mitigating those emissions. Because many of the environmental emissions from terrestrial animal agriculture and aquaculture are dependent on biogeochemical processes and can be altered by factors such as weather, microbial populations, and animal diet, there is a great need for empirical data quantifying emissions, testing mitigation strategies, and further developing mathematical models that can better represent observed data. A further challenge to LCAs is how to incorporate the social aspects of sustainability. While both environmental and economic impacts lend themselves to quantitative metrics, such a strategy with social considerations is difficult or impossible due to their subjective, qualitative nature.
Incorporation of social sustainability concerns into LCA methodology is challenging. Currently, LCA researchers use different scopes, scales, and environmental emission prediction methods that can make comparisons across the published literature difficult or inappropriate. (e.g., environmental impacts are commonly expressed per unit of production such as per kilogram of meat but are also expressed on the basis of land area or feed or calorie conversion). Research priorities for this area include:
- LCA, an effective methodology to evaluate whole-animal food production systems, should be improved by further efforts, such as LEAP, to harmonize methodologies and increase the transparency of methods and assumptions.
- Researchers in animal science and related disciplines should work collaboratively with LCA researchers to conduct empirical research that improves the methodologies and reduces the uncertainties of LCA. Research should provide empirical data to quantify emissions,
test mitigation strategies, and further develop and evaluate mathematical models that can better represent observed data and incorporate social sustainability.
Given the growing effects of social, cultural, and ethical concerns on the direction and effectiveness of research and technology transfer in animal agriculture (see Chapter 2), it is becoming increasingly important to employ transdisciplinary approaches that include both the natural and social sciences. One obvious area where social science and animal science research need to be better aligned is with respect to the economic consequences of research applications. From the point of view of commercial animal producers, market forces, government actions, and technical factors that affect production are essentially an economics problem. For example, diseases that reduce productivity also reduce production and therefore profitability. Diseases also impose costs on producers from treating animals and from the related disruptions to local and international markets and trade. Consequently, nearly all aspects of animal agriculture from breed selection to pasture and herd management have critical economic dimensions. If the net economic effect of all production activities is not positive, then production eventually ceases as producers search for more profitable land uses and production alternatives. At the same time, changes in economic forces impact the growth potential of animal agriculture and its ability to meet the growing demand for protein (see discussion on economics in Chapter 2). Some of the salient economic issues for the growth of U.S. animal agriculture relate to the expansion of biofuel production, consumer preferences, government intervention in markets, and market organization and comparative advantage.
The rapid expansion of biofuel production in the United States along with other economic factors, such as the rapid expansion of demand for food across the world and particularly in China due to income growth, have contributed to much higher feed prices which, in general, have negatively affected U.S. animal production and the profitability of animal agriculture (Taheripour et al., 2013). Changing consumer preferences also have effects on the economics of animal agriculture. For example, changing food preferences related to health concerns not only affect red meat consumption but also alter the relative profitability of the production of different animal types. The power of this economic force is
pressuring the ruminant animal industry to innovate and develop new technology and more efficient systems to compete with nonruminant systems, which are more vertically integrated, and to deliver products to consumers that better satisfy their desires for less fat in their diet.
Government intervention in the animal agricultural industry, such as grazing fees on public lands, animal waste regulations, and sanitary controls related to animal product trade, can provide positive social benefits; however, it also can distort market prices and costs, reduce market efficiency and ultimately limit the achievable profit from animal production, which constrains the ability of producers to adopt new technology. The way in which markets are organized (market structure) can also affect the profitability of food animal production. In the United States, cattle, sheep, and hog producers have historically been faced with relatively few buyers (packers). Consequently, food animal producers have expressed concerns over the years that the concentration of the packing industry provides packers with oligopoly-type market power, allowing them to pay low prices for slaughter animals and to sell meat products at higher prices than would occur with a more competitive packing industry. Such a market organization has the potential to limit the profitability of animal production while reducing consumer demand for animal products because of higher prices. On the other hand, government subsidies to animal producers, such as disaster assistance payments, enhance the profitability of animal agriculture and therefore promote the adoption of new technology and growth in food animal production.
Comparative advantage affects animal agriculture because unless a country has a comparative advantage in the production of food animals, the country will tend to import animal products rather than produce them.2 Thus, countries with plentiful land, which has few alternative uses, will have an advantage in extensive food animal production. For example, U.S. sheep production continues to decline and lamb imports continue to increase, not because U.S. producers are inefficient or high-cost producers but because, among other factors, the opportunity cost of continuing to use land traditionally dedicated to sheep production in the United States continues to rise as the demand for that land for urban expansion and for producing increasingly high-value corn and other crops and cattle continues to rise dramatically. The opportunity cost of
2 A country has a comparative advantage in the production and export of livestock products if that country can produce those products at a relatively lower cost in terms of resource use (e.g., land and labor).
land used for sheep production in Australia, on the other hand, is extremely low. Thus, Australia has a comparative advantage in the production and export of lamb because of relatively low opportunity cost of that production in Australia compared to the United States. Technology development and diffusion have helped maintain the low relative cost of U.S. cattle production and thus helped the country maintain a competitive industry despite growing beef imports from Australia and elsewhere with extensive land resources with low opportunity costs.
Potential contributions of social scientists to successful animal science research and technology transfer extend beyond the analysis of economic implications. The expertise of the committee members did not allow these potential contributions to be outlined in detail in this report, nor for specific recommendations to be made about the highest-priority social sciences research topics for the U.S. animal science research enterprise. In general, social science and bioethics research is critical to understanding the attitudes and values of both consumers and producers of animal products, and how those attitudes and values affect the acceptability of new technologies or practices (Croney and Anthony, 2010). Although some information is available regarding public attitudes about agriculture in the United States, particularly agricultural biotechnology (Food Insight, 2014), a more comprehensive approach toward obtaining this kind of information has been taken in Europe. The European Commission regularly conducts Eurobarometer surveys (EC, 2014) to assess public attitudes toward agriculturally related topics such as agricultural biotechnology, agricultural trade policy, food safety and security, and rural development. The European Union also recently funded a large-scale project to assess consumer and farmer attitudes to animal welfare throughout Europe with an associated animal sciences research program on this topic (Blokhuis et al., 2013). The successful development of a U.S. research agenda to increase sustainable intensification of animal food production nationally and globally would be facilitated by obtaining information about what the public knows about topics such as global food security and the application of technology to animal production, as well as their views about the ethics of raising and consuming animals, the environmental impacts of animal production, and the role of animal agriculture in society.
Karami and Keshavarz (2010) identify some other ways that social science research contributes to the achievement of agricultural sustainability. These include understanding gender impacts; developing
different paradigms for interpreting and achieving sustainability; exploring the cultural, economic, demographic, and attitudinal variables that explain the adoption of sustainable practices by farmers; and developing predictive models for technology and practice adoption. The authors also highlight the role of social scientists in informing decision makers about social impacts of their decisions. Social scientists and ethicists can also help to inform integration and communication strategies more generally, which is important both for structuring the animal science research agenda and for providing scientifically based information about animal agriculture within the framework of diverse stakeholder values (Swanson et al., 2011). Very few animal science departments in the United States have social science or bioethics faculty to carry out this type of research. Enhancing expertise in this area is also critical to properly prepare undergraduate, graduate, and veterinary students to address the societal issues underlying growing public concerns relative to food animal production and, ultimately, to serve the key stakeholders in animal agriculture, including all sectors of food animal production as well as retailers, consumers, and policy makers.
Although socioeconomic research is critical to the successful adoption of new technologies in animal agriculture, insufficient attention has been directed to such research. Few animal science departments in the United States have social sciences or bioethics faculty in their departments who can carry out this kind of research.
Socioeconomic and animal science research should be integrated so that researchers, administrators, and decision makers can be guided and informed in conducting and funding effective, efficient, and productive research and technology transfer.
3-13 Communication and Public Understanding
Although many people probably have opinions about food production practices related to their personal consumption of animal products, there is little evidence that the public is aware of the magnitude of the potential global food security crisis. The popular media report that there will be significant population growth by 2050, but often focus more on the environmental, health, and social sustainability aspects of modern production practices than on the relationships between those practices
and global food security needs. Animal agriculture is often the focus of significant criticism. Fraser (2001) has characterized what he refers to as the “New Perception” of animal agriculture in the growing popular literature—that it is detrimental to animal welfare, mainly controlled by large corporations, motivated by profit, causes increased world hunger, produces unhealthy food, and is harmful to the environment. He notes that this “New Perception” has raised important ethical issues about animal agriculture that cannot be dealt with simply by making counterclaims, and that the level of communication and discussion about these issues so far has been “simplistic” and failed to create a “climate of dialogue and consensus building.”
Croney et al. (2012) point out that although it is often assumed that reframing these kinds of issues or the language used to describe them are effective communication methods, this generally only has short-term effects on peoples’ views of issues. In addition, simply providing factual information does not necessarily inform peoples’ opinions—surveys have shown, for example, that although knowledge about biotechnology increases with educational level, acceptance of biotechnology does not (Priest, 2000). For animal biotechnology, or any other new technology or research application, to be accepted by the public, effective and responsible communication among scientific, community, industry, and government stakeholders to create a climate of dialogue is critical (Van Eenennaam, 2006).
Numerous researchers have begun the process of better understanding current communication gaps and methods to bridge them. For example, the University of Illinois maintains an extensive collection of international research publications in its Agricultural Communications Documentation Center (ACDC). Areas of research included in the ACDC include history, current status, trends, and outlook for agricultural communications and the impact of communications (1) on farmers, farm families, and farming; (2) on agri-marketing systems and processes; (3) on the food industry; (4) on food systems; (5) within agricultural organizations; (6) on relationships between agriculture and society; (7) on risk and issue management related to agriculture; (8) on nutrition and health; (9) on consumer decisions related to food and nutrition; (10) on rural communities and their development; (11) on agricultural policies; (12) on natural resources, environment, and sustainability; (13) on the renewable energy mission of society; (14) on agricultural trade and international affairs; and (15) on social movements related to agriculture.
ACDC has identified a number of priority areas that need research attention. Specifically, they suggest that communication research should be focused into three primary areas that explore how: (1) communication can enhance decision making within the agriculture sector; (2) communication can aid the public in effectively participating in decision making related to agriculture; and (3) to build competitive societal knowledge and intellectual capabilities. One important element of effective communication is trust in the person or organization providing that communication (Siegrist et al., 2010), since trust affects whether or not the information is perceived as being truthful, accurate, and respectful of values.
Collaborative efforts between agricultural schools and other university components can be helpful in achieving better understanding of communication issues. For example, schools of public health have departments with research expertise in understanding the role of communication in behavior, as well as departments focused on environmental health and public policy, which also overlap with issues of concern to animal agriculture research.
The committee recognizes a broad communication gap related to animal agriculture research and objectives between the animal science community and the consumer. This gap must be bridged if animal protein needs of 2050 are to be fulfilled.
There is a need to establish a strong focus on communications research as related to animal science research and animal agriculture, with the goals of enhancing knowledge dissemination, respectful stakeholder participation and engagement, and informed decision-making.
3-14 Integration and Systems Approaches
The above sections have discussed changes and potential knowledge gaps that should be addressed within disciplines and research areas; however, to address the sustainability of animal agriculture food systems, animal science disciplines must integrate across traditional boundaries and conduct collaborative, transdisciplinary research, extension, and education efforts. Sustainability encompasses environmental, economic, and social concerns. To best serve public needs, animal science
researchers must continue basic research to reduce scientific uncertainties within their respective disciplines. Researchers also must expand beyond traditional disciplines to increase understanding of the tradeoffs between areas of sustainability, and better understand public perceptions of animal agricultural systems as well as the value judgments made by researchers, animal agriculturalists, and consumers regarding sustainability. A systems approach that holistically integrates across disciplines is necessary.
3-14.1 Integrating Research, Extension, and Education Efforts
As previously discussed, animal agriculture in the United States has become increasingly intensified and concentrated, leading to concerns of nutrient pollution. Researchers, particularly those at land-grant universities, have responded to the increasing concentration of animal operations by creating research, extension, and education programs in nutrient management and environmental quality relating to livestock and poultry operations. For example, the Nutrient Management Spear Program (NMSP) in the Department of Animal Science at Cornell University has been developed to conduct applied research, extension, and education. The program combines animal science, manure management, and crop and soil science disciplines to advance holistic nutrient management of dairy farms in New York State. One tool that the program has developed is the whole-farm nutrient balance calculator, which has been used by both dairy farmers and students, and can be used as an important component of adaptive management3 approaches that improve environmental quality and economic viability over time (Figure 3-6; Soberon et al., 2013). Additionally, a capstone course in whole-farm nutrient management is taught to animal science and crop science students. The course covers a wide range of topics including CAFO regulations, crop nutrient requirements, and the nitrogen cycle, with the final portion of the class allowing students to create a comprehensive nutrient management plan for a cooperating case farm (Albrecht et al., 2006). Similar courses are offered at University of Wisconsin (Managing the Environmental Impacts of Livestock Operations) and Penn State University (Nutrient Management in Agricultural Systems). Although the NMSP offers a great example of combining research, extension, and education efforts to advance the environmental sustainability of food
3 From Rist et al. (2013), adaptive management is natural resource management conducted in a manner that purposely and explicitly increases knowledge and reduces uncertainty (Holling, 1978; Walters, 1986).
animal production, similar programs do not exist at all land-grant universities. Many have a single waste management or nutrient management specialist housed on campus, who may not be associated with the Department of Animal Science but rather with the Department of Agricultural or Biosystems Engineering. Although this should not eliminate the ability to collaborate with animal scientists, the separation of animal waste specialists from departments of animal science can sometimes create an obstacle to integrated, collaborative research. This “silo effect” of separating disciplines, along with often limited funding support, can stifle the creation of transdisciplinary environmental management or sustainability programs for animal agricultural production that contain research, extension, and education elements.
One useful tool in eliminating regional barriers and enhancing knowledge transfer in extension programing is the eXtension website (eXtension, 2014b). In the area of nutrient management, there is the Livestock and Poultry Environmental Learning Center, which has fact sheets, tools, and webinars on topics such as air quality, environmental planning, manure treatment, pathogens, and climate change (eXtension, 2014a). Additionally, there is a separate extension project funded by USDA NIFA, called “Animal Agriculture and Climate Change,” which created a free online course covering topics such as the science behind climate change, GHG emission sources, GHG emission mitigation and adaptation to climate change (USDA NIFA, 2013). In addition to the extension-focused “Animal Agriculture and Climate Change” project,
FIGURE 3-6 Adaptive management for sustainability of agricultural farming systems.
SOURCE: NRC (2010).
there are other ongoing USDA NIFA-funded integrated research projects (integrated with extension and/or education components) that are related to either adaptation to climate change and/or mitigation of GHG emissions. Some of these projects include “Climate Change Mitigation and Adaptation in Dairy Production Systems of the Great Lakes region” (Project No. WIS01693) and “Resilience and Vulnerability of Beef Cattle Production in the Southern Great Plains Under Changing Climate, Land Use and Markets” (Project No. OKL02857). USDA also supports the Sustainable Agriculture Research and Education (SARE) program, which has provided funding for over 5,000 projects to producers, extension educators, researchers, nonprofits, and communities since the late 1980s (SARE, 2012). Funded projects have included on-farm renewable energy, no-till and conservation agriculture, nutrient management, crop and food animal diversity, and systems research (SARE, 2012).
While these examples provide an indication of potentially successful strategies, there is a need to further improve understanding and encourage wider application of outcome-based solutions for environmental management. Such an effort requires integrated research, extension, and education activities that are unlikely to be funded solely by a single producer group or private company because of resource limitations and, in many cases, a lack of clear commercial outcomes for research. Public funding and strategic public–private partnerships will be critical if progress in mitigating environmental impacts is desired. An example of a broad public–private partnership sustainability research effort, which goes beyond focusing just on environmental impacts, is the Coalition for a Sustainable Egg Supply (Box 3-13). Land-grant universities are uniquely qualified to conduct integrated research, as they have done for 100 years, particularly field-to-fork research that encompasses all phases of animal production to the consumer; however, the decline in public funding (both state and federal) in recent decades has led to an erosion of land-grant universities’ abilities to meet societal demand for integrated research.
Coalition for a Sustainable Egg Supply
The Coalition for a Sustainable Egg Supply (CSES) provides a model for how public–private partnerships can be effective in initiating and supporting multidisciplinary research on the sustainability of animal agriculture. As discussed in Box 2-4, the egg industry in the United States is in a state of transition due to stakeholder pressure to transition from conventional cage housing for hens to alternative housing because of concerns about hen welfare. In 2006, the American Egg Board provided funding for teams of social and natural scientists to conduct literature reviews to determine the knowledge base and information gaps regarding the effects of different hen housing systems on environmental, economic, and social sustainability (Swanson et al., 2011). These reviews identified not only significant knowledge gaps but concluded that most research had been conducted in the European Union on an experimental rather than a commercial scale. A need was identified for commercial-scale studies conducted under U.S. conditions, which stimulated the formation of the CSES.
The CSES is a multistakeholder group involving academic institutions, retailers, food distributors, egg producers, scientific and veterinary organizations, and nongovernmental organizations (http://www2.sustainableeggcoalition.org/). Building on the findings of the American Egg Board project, the CSES provided approximately $6.6 million in funding to researchers at academic institutions (Michigan State University, University of California, and Iowa State University) and USDA ARS to conduct a multiyear commercial-scale study of three housing alternatives for egg-laying hens in the United States The Coalition researchers worked to better understand the impact of these laying-hen housing systems on a sustainable supply of eggs by conducting integrated multidisciplinary research on the environmental, worker health and safety, hen health and welfare, economic, and food safety and quality aspects of those systems. In conjunction, the Center for Food Integrity (http://www.foodintegrity.org/), which facilitates the CSES, is conducting research to better understand consumers’ attitudes toward egg production and how those attitudes are affected when consumers are informed about the research results. This project will identify the sustainability tradeoffs between systems in order to allow stakeholders to make informed decisions going forward.
3-14.2 Integrating Research Disciplines to Understand Sustainability Tradeoffs
While there are often synergies across the three pillars of sustainability (environmental, economic, and social), there are also tradeoffs that have been largely neglected by past animal science research. For example, Capper et al. (2008) compared the environmental impact of three dairy production systems used to produce equivalent amounts of milk. The three systems included a conventional system, conventional system plus the adoption of recombinant bovine somatotropin (rbST), and an organic system. Capper et al. (2008) found that the adoption of rbST technology resulted in 8 percent fewer animals, 5 percent less land area, 5-6 percent reduced animal waste, and 6 percent reduction in GHG production compared to the conventional system. By contrast, the organic system resulted in a more negative environmental impact with a 25 percent increase in animal numbers, 20 percent increase in land area, and 13 percent increase in GHG emissions compared to the conventional system (Capper et al., 2008). Although the adoption of technologies such as rbST have economic and environmental sustainability benefits due to improving the efficiency of resource conversion into dairy products, the social sustainability implications of technologies used in animal production are less clear. In the United States, there has been a major shift away from selling fluid milk from cows treated with rbST in the past decade. Indeed, it is nearly impossible to find fluid milk sold without the label “from cows not treated with rbST (or rBGH).” The caveat to such labels is the “Food and Drug Administration (FDA) has determined there is no significant difference between milk from rbST treated cows and non-rbST treated cows.” Despite the assurance by the FDA that milk from rbST treated cows is safe, consumer resistance to rbST has been driven by concerns of IGF-1 levels in milk, the possibility of increased health risks to children exposed to milk from rbST treated cows, and potential impacts on dairy cattle welfare (Collier and Bauman, 2014). While these concerns have been determined to be unfounded (Collier and Bauman, 2014), consumer resistance remains, translating into retailer pressure for dairy farmers to stop using rbST (Olynk et al., 2012). It is unclear if consumers are aware of the potential environmental benefits of using rbST and if that would have any impact on the reluctance of many consumers to buy dairy products from cattle treated with rbST.
A more recent example of the tradeoff challenges for biotechnology is the use of the beta-agonist zilpaterol hydrochloride in finishing beef
cattle. In the literature, both live animal experiments and a study using modeling techniques have found that use of growth-promoting technologies, such as beta-agonists, can decrease environmental impacts and resource use per unit of beef (Cooprider et al., 2011; Capper and Hayes, 2012; Stackhouse-Lawson et al., 2013). However, in August 2013, because of concerns over zilpaterol hydrochloride’s impact on animal welfare, the company Tyson announced that it would stop harvesting cattle that had been fed beta-agonists in their slaughterhouses. The manufacturer of zilpaterol, Merck Animal Health, eventually removed the product from the market while investigating the animal welfare concerns. Lonergan et al. (2014) analyzed the effect of beta-agonists (both zilpaterol and ractopomine hydrochloride [Elanco Animal Health]) on cattle mortality. Though the mortality rates for the thousands of cattle in the datasets analyzed were very low, there was a significant increase in death loss for cattle treated with beta-agonists, particularly in summer months (Lonergan et al., 2014). Although the mechanisms or potential interactions that cause increased mortality and potential lameness (the primary welfare concern that led Tyson to its decision) still need to be elucidated, the case of zilpaterol hydrochloride illustrates the need for cooperation across disciplines within animal and veterinary sciences, as well as with social sciences to determine acceptability of biotechnologies such as beta-agonists. Consumers are likely largely unaware of the array of technologies used in animal agriculture, the reason for use, and the potential costs and benefits. The tradeoffs surrounding the social, environmental, and economic facets of sustainability have gone largely ignored and unquantified in the animal sciences, pointing to a need for further collaboration, training, and research in the future.
Beyond biotechnology, improved animal husbandry practices and housing systems that can affect animal longevity, fertility, and productivity can also affect environmental impacts per unit of output. Place and Mitloehner (2014) and Tucker et al. (2013) highlighted the synergy between some, but not all, animal welfare concerns and environmental quality. An example of a synergistic relationship between animal health and welfare and environmental impact is mastitis in the dairy industry. Reducing the incidence of mastitis (inflammation of the mammary gland that can be painful to the cow) has been shown to reduce dairy production’s contribution to climate change, eutrophication, and acidification by decreasing the losses of human-consumable milk (Hospido and Sonesson, 2005).
Currently, there is limited research linking the disciplines of animal welfare, animal health, genetics, and the environment. The data gap on the connections and interactions of these disciplines represents an opportunity for animal science research to increase our collective knowledge and improve tradeoff analyses between environmental quality and other aspects of sustainable animal agriculture.
There are several examples of integrated research, extension, and education efforts; however, relatively few were considered to be focused on sustainable animal agriculture and food systems. In some instances, the use of biotechnologies can simultaneously improve production efficiency and reduce environmental impacts per unit of output; however, the social acceptability and impacts of these biotechnologies on animal welfare should also be considered in research. Research priorities for this area include:
- A coordinated approach to engage with the public, policy makers, animal agriculturalists, and animal scientists is required to better understand, respond to, and communicate the tradeoffs of biotechnological solutions across the economic, social, and environmental components of sustainability.
- To tackle the issues of sustainability in animal agriculture, public funding should be guided by a twofold objective for support—projects that take a transdisciplinary approach and integrate research with extension and/or education efforts, and projects that continue to increase fundamental knowledge within the disciplines of animal science.
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