Food Animal Production Systems Research Articles

161 A System Dynamics Model of Bovine Respiratory Disease Epidemiology and Prevention Strategies in an Integrated Beef Production System

Abstract Bovine respiratory disease (BRD) is a complex multifactorial disease that results in more than $1 billion in economic losses for the United States beef cattle industry, accounting for approximately 30% of the total antimicrobial use (AMU) in food animal production systems. The prevalence and production losses due to BRD vary significantly between different production systems, and is influenced by the host, pathogen, and environmental risk factors. These multiple risk factors together have a cumulative effect and will increase the prevalence of the disease if no preventive strategies are implemented in the system. Moreover, the increased AMU to treat BRD results in antimicrobial resistance, further complicating the issue. A linear, event-based solution to address such a complex problem will fail to consider the feedback loops and time delays in the system and may cause unintended consequences that might make the problem even more complex. Hence, we propose a more comprehensive system dynamic model to simulate an integrated beef production system with respect to BRD and predict the dynamic behavior of the system under different preventive strategies currently available to the beef industry. Our conceptual model accounts for host risk factors (auxiliary variables in the model) like age, nutritional status, daily weight gain, prior exposure to pathogens, and genetics. The environmental risk factors such as air quality, transportation, temperature humidity index, overcrowding, and source of animals were also included in the model. The various preventative strategies to reduce the incidence of BRD, including vaccination, biosecurity, adequate colostrum, and nutrition, were also added to the model. The key outcome variables considered were net profitability and AMU. The model simulates multiple scenarios by leveraging the auxiliary variables and can provide information about the system’s net profitability and total AMU. The model explains the interconnected effect of various risk factors associated with BRD in multiple complex scenarios and helps understand the combined effect of adopting various preventive strategies and host-environmental factors in controlling BRD. The initial result from our dynamic model suggests that using a combination of preventive measures and avoiding the selected host-environmental risk factors can minimize AMU while improving profit. The long-term goal of our modeling effort is to enable the beef system stakeholders to make informed decisions and strategies to mitigate the impact of BRD, thereby contributing to improved profitability. Through a systems-thinking approach, our model can contribute to addressing the challenges in BRD management currently faced by the US-based integrated beef production systems.

Mycotoxins Adsorbents in Food Animal Production

Mycotoxins, toxic secondary metabolites produced by molds, pose a significant threat to food animal production, as they can lead to adverse health effects, reduced productivity, and economic losses. In response to this challenge, mycotoxin adsorbents have emerged as a promising solution to mitigate the harmful effects of mycotoxins in livestock. This paper presents a comprehensive review of the positive influence of mycotoxin adsorbents in food animal production. The review discusses the mechanisms by which mycotoxin adsorbents function, including adsorption, binding, and inactivation of mycotoxins. Various types of mycotoxin adsorbents are explored, encompassing natural adsorbents such as clays, zeolites, and activated carbons, as well as synthetic polymers. The influence of mycotoxin adsorbents on the immune system, gut health, and overall well-being of food animals is examined. Furthermore, the review delves into the challenges and limitations associated with mycotoxin adsorbents, including variability in mycotoxin contamination, dosage, and timing of administration. Strategies for optimizing their use, such as mycotoxin monitoring and mycotoxin binder selection, are discussed to ensure maximum effectiveness. In conclusion, the positive influence of mycotoxin adsorbents in food animal production cannot be understated. By offering a proactive and cost-effective means of mycotoxin management, mycotoxin adsorbents play a pivotal role in safeguarding animal health and the economic viability of livestock operations. This review underscores the significance of mycotoxin adsorbents as essential tools in ensuring the safety and productivity of food animal production systems.

Combined Quantification and Deep Serotyping for Salmonella Risk Profiling in Broiler Flocks.

Despite a reduction of Salmonella contamination on final poultry products, the level of human salmonellosis cases attributed to poultry has remained unchanged over the last few years. There needs to be improved effort to target serovars which may survive antimicrobial interventions and cause illness, as well as to focus on lessening the amount of contamination entering the processing plant. Advances in molecular enumeration approaches allow for the rapid detection and quantification of Salmonella in pre- and postharvest samples, which can be combined with deep serotyping to properly assess the risk affiliated with a poultry flock. In this study, we collected a total of 160 boot sock samples from 20 broiler farms across four different integrators with different antibiotic management programs. Overall, Salmonella was found in 85% (68/80) of the houses, with each farm having at least one Salmonella-positive house. The average Salmonella quantity across all four complexes was 3.6 log10 CFU/sample. Eleven different serovars were identified through deep serotyping, including all three key performance indicators (KPIs; serovars Enteritidis, Infantis, and Typhimurium) defined by the U.S. Department of Agriculture-Food Safety and Inspection Service (USDA-FSIS). There were eight multidrug resistant isolates identified in this study, and seven which were serovar Infantis. We generated risk scores for each flock based on the presence or absence of KPIs, the relative abundance of each serovar as calculated with CRISPR-SeroSeq (serotyping by sequencing the clustered regularly interspaced palindromic repeats), and the quantity of Salmonella organisms detected. The work presented here provides a framework to develop directed processing approaches and highlights the limitations of conventional Salmonella sampling and culturing methods. IMPORTANCE Nearly one in five foodborne Salmonella illnesses are derived from chicken, making it the largest single food category to cause salmonellosis and indicating a need for effective pathogen mitigation. Although industry has successfully reduced Salmonella incidence in poultry products, there has not been a concurrent reduction in human salmonellosis linked to chicken consumption. New efforts are focused on improved control at preharvest, which requires improved Salmonella surveillance. Here, we present a high-resolution surveillance approach that combines quantity and identity of Salmonella in broiler flocks prior to processing which will further support improved Salmonella controls in poultry. We developed a framework for this approach, indicating that it is possible and important to harness deep serotyping and molecular enumeration to inform on-farm management practices and to minimize risk of cross-contamination between flocks at processing. Additionally, this framework could be adapted to Salmonella surveillance in other food animal production systems.

Prevalence and Phylodiversity of ESBL-Producing Coliforms Isolated from Ruminant Mastitis in Nigeria

Abstract The public health threat posed by Extended-spectrum beta-lactamase producing E. coli (ESBL-EC) in food animal production systems has attracted global attention. Data on the prevalence, diversity and genetic characteristics of ESBL-producing coliforms are key to advocacy on promoting responsible antimicrobial stewardship and proper planning of control strategies. The coliforms were isolated from 1052 milk samples of 160 cows, 103 ewes and 103 does with mastitis in Plateau State, Nigeria and analysed for ESBL production by phenotypic, biochemical, antimicrobial sensitivity and genetic characterization. The percentage of occurrence of clinical mastitis in cows, ewes, and does were 0.2 %, 0 %, 1.5 % respectively, while the percentage occur-rence of subclinical mastitis in ruminants were 18.1 %, 28.2 % and 38.3 % respectively. From the 677 isolates, 31.3 % (n = 212) were ESBL producing coliforms, with a prevalence of 48.6 %, 18.4 %, 12.7 %, 8.9 %, 5.7 %, 3.8 % and 1.9 % for E. coli, K. pneumoniae, C. freundii, K. aerogenes, S. marcescens, K. oxytoca and E. cloacae, respectively. The genetic characterization revealed a higher prevalence of bla CTX-M than bla TEM in the samples analysed (24.39 % vs. 12.19 %). High pairwise identity was observed among the bla CTX-M and bla TEM gene sequences obtained in this study, but they displayed high phylodiversity with sequences from ruminants and humans from other climes. The bla SHV gene was not detected. Multidrug resistances especially to the commonly used antimicrobials; ofloxacin, gentamycin and streptomycin in veterinary practice in Nigeria were observed. This has public health implications considering the fact that consumption of raw unpasteurized milk is a common practice in some cultures in Nigeria. Such practise will facilitate the transfer of multidrug resistant coliforms to humans resulting in the complications of treatment outcomes. To the best of our knowledge this is the first genetic characterization of ESBL-producing agents from ruminant mastitis in Nigeria.

Salmonella in Swine: Prevalence, Multidrug Resistance, and Vaccination Strategies.

An estimated 1.3 million Salmonella infections and 420 deaths occur annually in the United States, with an estimated economic burden of $3.7 billion. More than 50% of US swine operations test positive for Salmonella according to the National Animal Health Monitoring System, and 20% of Salmonella from swine are multidrug resistant (resistant to ≥3 antimicrobial classes) as reported by the National Antimicrobial Resistance Monitoring System. This review on Salmonella in swine addresses the current status of these topics by discussing antimicrobial resistance and metal tolerance in Salmonella and the contribution of horizontal gene transfer. A major challenge in controlling Salmonella is that Salmonella is a foodborne pathogen in humans but is often a commensal in food animals and thereby establishes an asymptomatic reservoir state in such animals, including swine. As food animal production systems continue to expand and antimicrobial usage becomes more limited, the need for Salmonella interventions has intensified. A promising mitigation strategy is vaccination against Salmonella in swine to limit animal, environmental, and food contamination.

Extraintestinal Pathogenic Escherichia coli: Virulence Factors and Antibiotic Resistance.

The One Health approach emphasizes the importance of antimicrobial resistance (AMR) as a major concern both in public health and in food animal production systems. As a general classification, E. coli can be distinguished based on the ability to cause infection of the gastrointestinal system (IPEC) or outside of it (ExPEC). Among the different pathogens, E. coli are becoming of great importance, and it has been suggested that ExPEC may harbor resistance genes that may be transferred to pathogenic or opportunistic bacteria. ExPEC strains are versatile bacteria that can cause urinary tract, bloodstream, prostate, and other infections at non-intestinal sites. In this context of rapidly increasing multidrug-resistance worldwide and a diminishingly effective antimicrobial arsenal to tackle resistant strains. ExPEC infections are now a serious public health threat worldwide. However, the clinical and economic impact of these infections and their optimal management are challenging, and consequently, there is an increasing awareness of the importance of ExPECs amongst healthcare professionals and the general public alike. This review aims to describe pathotype characteristics of ExPEC to increase our knowledge of these bacteria and, consequently, to increase our chances to control them and reduce the risk for AMR, following a One Health approach.

Antibiotic Usage and Resistance in Food Animal Production: What Have We Learned from Bangladesh?

Irrational and inappropriate use of antibiotics in commercial chicken and aquaculture industries can accelerate the antibiotic resistance process in humans and animals. In Bangladesh, the growing commercial chicken and aquaculture industries are playing significantly important roles in the food value chain. It is necessary to know the antibiotic usage practices and antibiotic resistance in food animal production to design rational policies, guidelines, and interventions. We conducted a narrative review to understand the level of antibiotic usage and resistance in food animal production in Bangladesh. Information about antibiotic usage in different food animal production systems, including commercial chickens and aquaculture in Bangladesh is inadequate. Only a few small-scale studies reported that the majority (up to 100%) of the broiler and layer chicken farms used antibiotics for treating and preventing diseases. However, numerous studies reported antibiotic-resistant bacteria of public health importance in commercial chicken, fish, livestock, and animal origin food. The isolates from different pathogenic bacteria were found resistant against multiple antibiotics, including quinolones, the third or fourth generation of cephalosporins, and polymyxins. Veterinary practitioners empirically treat animals with antibiotics based on presumptive diagnosis due to inadequate microbial diagnostic facilities in Bangladesh. Intensive training is helpful to raise awareness among farmers, feed dealers, and drug sellers on good farming practices, standard biosecurity practices, personal hygiene, and the prudent use of antibiotics. Urgently, the Government of Bangladesh should develop and implement necessary guidelines to mitigate irrational use of antibiotics in food animals using a multi-sectoral One Health approach.

Non-Steroidal Anti-Inflammatory Drugs: Pharmacokinetics and Mitigation of Procedural-Pain in Cattle.

Common routine management practices in cattle, such as castration and disbudding, are recognized as being painful. In the United States (U.S.), these procedures are frequently performed without pain mitigation and there are currently no drugs federally approved for such use. Non-steroidal anti-inflammatory drugs, such as meloxicam, flunixin meglumine and aspirin, are the most commonly used analgesics in U.S. food-animal production systems. However, the body of research investigating the effectiveness of these pharmaceuticals to control pain in cattle at castration and disbudding has not been comprehensively evaluated. Therefore, this review examined existing literature to summarize meloxicam, flunixin and aspirin (1) pharmacokinetics (PK) and (2) administration outcome in regard to pain control during castration and disbudding procedures, in cattle. Following systematic searches and screening, 47 PK and 44 publications were extracted for data and are presented. The sample size contained notable variability and a general deficiency of validated and replicated methodologies for assessing pain in cattle remain substantial challenges within this research area. Future research should prioritize replication of pain assessment methodologies across different experimental conditions to close knowledge gaps identified by the present study and facilitate examination of analgesic efficacy.

“What a Waste”—Can We Improve Sustainability of Food Animal Production Systems by Recycling Food Waste Streams into Animal Feed in an Era of Health, Climate, and Economic Crises?

Food waste has been a major barrier to achieving global food security and environmental sustainability for many decades. Unfortunately, food waste has become an even bigger problem in many countries because of supply chain disruptions during the COVID-19 pandemic and African Swine Fever epidemic. Although Japan and South Korea have been leaders in recycling food waste into animal feed, countries that produce much greater amounts of food waste, such as the United States and the European Union, have lagged far behind. Concerns about the risk of transmission of bacteria, prions, parasites, and viruses have been the main obstacles limiting the recycling of food waste streams containing animal-derived tissues into animal feed and have led to government regulations restricting this practice in the U.S. and EU. However, adequate thermal processing is effective for inactivating all biological agents of concern, perhaps except for prions from infected ruminant tissues. The tremendous opportunity for nitrogen and phosphorus resource recovery along with several other environmental benefits from recycling food waste streams and rendered animal by-products into animal feed have not been fully appreciated for their substantial contribution toward solving our climate crisis. It is time to revisit our global approach to improving economic and environmental sustainability by more efficiently utilizing the abundant supply of food waste and animal tissues to a greater extent in animal feed while protecting human and animal health in food animal production systems.

Mobility of β-Lactam Resistance Under Bacterial Co-infection and Ampicillin Treatment in a Mouse Model.

Ingestion of food- or waterborne antibiotic-resistant bacteria may lead to the dissemination of antibiotic-resistance genes in the gut microbiota and the development of antibiotic-resistant bacterial infection, a significant threat to animal and public health. Food or water may be contaminated with multiple resistant bacteria, but animal models on gene transfer were mainly based on single-strain infections. In this study, we investigated the mobility of β-lactam resistance following infection with single- versus multi-strain of resistant bacteria under ampicillin treatment. We characterized three bacterial strains isolated from food-animal production systems, Escherichia coli O80:H26 and Salmonella enterica serovars Bredeney and Heidelberg. Each strain carries at least one conjugative plasmid that encodes a β-lactamase. We orally infected mice with each or all three bacterial strain(s) in the presence or absence of ampicillin treatment. We assessed plasmid transfer from the three donor bacteria to an introduced E. coli CV601gfp recipient in the mouse gut, and evaluated the impacts of the bacterial infection on gut microbiota and gut health. In the absence of ampicillin treatment, none of the donor or recipient bacteria established in the normal gut microbiota and plasmid transfer was not detected. In contrast, the ampicillin treatment disrupted the gut microbiota and enabled S. Bredeney and Heidelberg to colonize and transfer their plasmids to the E. coli CV601gfp recipient. E. coli O80:H26 on its own failed to colonize the mouse gut. However, during co-infection with the two Salmonella strains, E. coli O80:H26 colonized and transferred its plasmid to the E. coli CV601gfp recipient and a residential E. coli O2:H6 strain. The co-infection significantly increased plasmid transfer frequency, enhanced Proteobacteria expansion and resulted in inflammation in the mouse gut. Our findings suggest that single-strain infection models for evaluating in vivo gene transfer may underrepresent the consequences of multi-strain infections following the consumption of heavily contaminated food or water.

Nitrogen input strategies in pastures: mineral fertilizer, bacterial inoculant and consortium with forage peanuts

Brazil is a prominent country in the production of beef cattle, where pastures are the basis for ruminant feed, because it is the most economical and practical form of food supply. Nitrogen is the main nutrient for maintaining and increasing the productivity of forage grasses, but its application is one of the most costly and greenhouse gas emitting practices for the system. The introduction of this element into the soil-plant-animal complex can be directly, with mineral fertilizers and with other alternatives, for example, through symbiosis of plants with atmospheric nitrogen fixing bacteria and plant growth promoting bacteria. Owing to future climate changes and increasing food demand, plant and animal production systems need to be increasingly competitive, responsible and efficient. Therefore, the objective of this study was to discuss nitrogen supply strategies in pastures: nitrogen fertilization, inoculation with Azospirillum brasilense and consortium with forage peanuts.

Human, animal and environmental contributors to antibiotic resistance in low-resource settings: integrating behavioural, epidemiological and One Health approaches.

Antibiotic resistance (ABR) is recognized as a One Health challenge because of the rapid emergence and dissemination of resistant bacteria and genes among humans, animals and the environment on a global scale. However, there is a paucity of research assessing ABR contemporaneously in humans, animals and the environment in low-resource settings. This critical review seeks to identify the extent of One Health research on ABR in low- and middle-income countries (LMICs). Existing research has highlighted hotspots for environmental contamination; food-animal production systems that are likely to harbour reservoirs or promote transmission of ABR as well as high and increasing human rates of colonization with ABR commensal bacteria such as Escherichia coli However, very few studies have integrated all three components of the One Health spectrum to understand the dynamics of transmission and the prevalence of community-acquired resistance in humans and animals. Microbiological, epidemiological and social science research is needed at community and population levels across the One Health spectrum in order to fill the large gaps in knowledge of ABR in low-resource settings.

Small-Scale Food Animal Production and Antimicrobial Resistance: Mountain, Molehill, or Something in-between?

Summary:Small-scale food animal production is widely practiced around the globe, yet it is often overlooked in terms of the environmental health risks. Evidence suggests that small-scale food animal producers often employ the use of antimicrobials to improve the survival and growth of their animals, and that this practice leads to the development of antimicrobial resistance (AMR) that can potentially spread to humans. The nature of human–animal interactions in small-scale food animal production systems, generally practiced in and around the home, likely augments spillover events of AMR into the community on a scale that is currently unrecognized and deserves greater attention. https://doi.org/10.1289/EHP2116

Brazilian Citizens' Opinions and Attitudes about Farm Animal Production Systems.

Simple SummaryThe inclusion of societal input is needed for food animal production industries to retain their “social license to operate”. Little is known about the knowledge and attitudes of Brazilian citizens regarding food animal production systems. The aim of this study was to explore the beliefs and attitudes of Brazilians not associated with livestock production towards farm animal production systems. Overall, our participants expressed a preference for free-range, cage-free, and more “natural” production systems. They also expressed concerns with livestock production systems that limited the movement or expression of natural behaviours, particularly those that they associated with animal suffering or distress. They recognized farm animals as deserving respect and dignity beyond the provision of basic needs. Our findings indicate that Brazil’s current farm animal housing practices that are associated with restriction of movement may not align with societal expectations.The inclusion of societal input is needed for food animal production industries to retain their “social license to operate”; failure to engage with the public on this topic risks the long-term sustainability of these industries. The primary aim of this study was to explore the beliefs and attitudes of Brazilians citizens not associated with livestock production towards farm animal production. A related secondary aim was to identify the specific beliefs and attitudes towards systems that are associated with restriction of movement. Each participant was shown pictures representing two of five possible major food animal industries (laying hens, beef cattle, pregnant sows, lactating sows, and poultry meat). Participants were presented a six pages survey that included demographic questions plus two sets of two pictures and a series of questions pertaining to the pictures. Each set of pictures represented a particular industry where one picture represented a housing type that is associated with behavioural restrictions and the other picture represented a system that allowed for a greater degree of movement. Participants were asked their perceptions on the prevalence of each system in Brazil, then their preference of one picture vs. the other, and the reasons justifying their preference. Immediately following, the participant repeated the same exercise with the second set of two pictures representing another industry followed by the same series of questions as described above. Quantitative data were analysed with mixed effects logistic regression, and qualitative responses were coded into themes. The proportion of participants that believed animals are reared in confinement varied by animal production type: 23% (beef cattle), 82% (poultry), 81% (laying hens), and 60% (swine). A large majority (79%) stated that farm animals are not well-treated in Brazil. Overall, participants preferred systems that were not associated with behavioural restriction. The preference for free-range or cage-free systems was justified based on the following reasons: naturalness, animals’ freedom to move, and ethics. A minority of participants indicated a preference for more restrictive systems, citing reasons associated with food security and food safety, increased productivity and hygiene. Our results suggest that the majority of our participants, preferred farm animal production systems that provide greater freedom of movement, which aligned with their perception that these systems are better for the animal. Our results provide some evidence that the current farm animal housing practices that are associated with restriction of movement, which are gaining traction in Brazil, may not align with societal expectations.

Proactive Risk Assessments and the Continuity of Business Principles: Perspectives on This Novel, Combined Approach to Develop Guidance for the Permitted Movement of Agricultural Products during a Foot-and-Mouth Disease Outbreak in the United States.

Animal diseases such as foot-and-mouth disease (FMD) have the potential to severely impact food animal production systems. Paradoxically, the collateral damage associated with the outbreak response may create a larger threat to the food supply, social stability, and economic viability of rural communities than the disease itself. When FMD occurs in domestic animals, most developed countries will implement strict movement controls in the area surrounding the infected farm(s). Historically, stopping all animal movements has been considered one of the most effective ways to control FMD and stop disease spread. However, stopping all movements in an area comes at a cost, as there are often uninfected herds and flocks within the control area. The inability to harvest uninfected animals and move their products to processing interrupts the food supply chain and has the potential to result in an enormous waste of safe, nutritious animal products, and create animal welfare situations. In addition, these adverse effects may negatively impact agriculture businesses and the related economy. Effective disease control measures and the security of the food supply thus require a balanced approach based on science and practicality. Evaluating the risks associated with the movement of live animals and products before an outbreak happens provides valuable insights for risk management plans. These plans can optimize animal and product movements while preventing disease spread. Food security benefits from emergency response plans that both control the disease and keep our food system functional. Therefore, emergency response plans must aim to minimize the unintended negative consequence to farmers, food processors, rural communities, and ultimately consumers.

Influenza A Virus Surveillance in Waterfowl in Missouri, USA, 2005-2013.

Missouri, United States, is located within the Mississippi Migratory Bird Flyway where wild waterfowl stop to feed and rest during migration and, weather permitting, to overwinter. Historically, Missouri has experienced sporadic influenza A virus (IAV) outbreaks in poultry and commercial swine. The introduction of IAVs from wild, migratory waterfowl is one possible source for the IAV, IAV genomic segments, or both involved in these outbreaks in key agricultural species. During 2005 through 2013, 3984 cloacal swabs were collected from hunter-harvested waterfowl in Missouri as part of an active IAV surveillance effort. Twenty-four avian species were represented in the sample population and 108 (2.7%) of the samples tested positive for IAV recovery. These IAV isolates represented 12 HA and nine NA subtypes and at least 27 distinct HA-NA combinations. An H14 IAV isolate recovered in Missouri during the sample period provided evidence for further establishment of the H14 subtype in North American wild waterfowl and gave proof that the previously rare subtype is more genetically diverse than previously detected. The present surveillance effort also produced IAV isolates that were genomically linked to the highly pathogenic H7N3 IAV strain that emerged in 2012 and caused severe disease in Mexico's domestic poultry. The presence of antigenically diverse IAV's circulating in wild waterfowl in the vicinity of commercial poultry and swine, along with the association of several wild-bird-lineage IAV genomic segments in viruses infecting poultry in North America, justifies continued attention to biosecurity efforts in food animal production systems and ongoing active IAV surveillance in wild birds.

Development of a Salmonella cross-protective vaccine for food animal production systems

Intensive livestock production is associated with increased Salmonella exposure, transmission, animal disease, and contamination of food and water supplies. Modified live Salmonella enterica vaccines that lack a functional DNA adenine methylase (Dam) confer cross-protection to a diversity of salmonellae in experimental models of murine, avian, ovine, and bovine models of salmonellosis. However, the commercial success of any vaccine is dependent upon the therapeutic index, the ratio of safety/efficacy. Herein, secondary virulence-attenuating mutations targeted to genes involved in intracellular and/or systemic survival were introduced into Salmonella dam vaccines to screen for vaccine candidates that were safe in the animal and the environment, while maintaining the capacity to confer cross-protective immunity to pathogenic salmonellae serotypes. Salmonella dam mgtC, dam sifA, and dam spvB vaccine strains exhibited significantly improved vaccine safety as evidenced by the failure to give rise to virulent revertants during the infective process, contrary to the parental Salmonella dam vaccine. Further, these vaccines exhibited a low grade persistence in host tissues that was associated with reduced vaccine shedding, reduced environmental persistence, and induction of cross-protective immunity to pathogenic serotypes derived from infected livestock. These data indicate that Salmonella dam double mutant vaccines are suitable for commercial applications against salmonellosis in livestock production systems. Reducing pre-harvest salmonellae load through vaccination will promote the health and productivity of livestock and reduce contamination of livestock-derived food products, while enhancing overall food safety.

Can probiotics improve the environmental microbiome and resistome of commercial poultry production?

Food animal production systems have become more consolidated and integrated, producing large, concentrated animal populations and significant amounts of fecal waste. Increasing use of manure and litter as a more “natural” and affordable source of fertilizer may be contributing to contamination of fruits and vegetables with foodborne pathogens. In addition, human and animal manure have been identified as a significant source of antibiotic resistance genes thereby serving as a disseminator of resistance to soil and waterways. Therefore, identifying methods to remediate human and animal waste is critical in developing strategies to improve food safety and minimize the dissemination of antibiotic resistant bacteria. In this study, we sought to determine whether withdrawing antibiotic growth promoters or using alternatives to antibiotics would reduce the abundance of antibiotic resistance genes or prevalence of pathogens in poultry litter. Terminal restriction fragment length polymorphism (T-RFLP) paired with high throughput sequencing was used to evaluate the bacterial community composition of litter from broiler chickens that were treated with streptogramin growth-promoting antibiotics, probiotics, or prebiotics. The prevalence of resistance genes and pathogens was determined from sequencing results or PCR screens of litter community DNA. Streptogramin antibiotic usage did not elicit statistically significant differences in Shannon diversity indices or correlation coefficients among the flocks. However, T-RFLP revealed that there were inter-farm differences in the litter composition that was independent of antibiotic usage. The litter from all farms, regardless of antibiotic usage, contained streptogramin resistance genes (vatA, vatB, and vatE), macrolide-lincosamide-streptogramin B resistance genes (ermA and ermB), the tetracycline resistance gene tetM and class 1 integrons. There was inter-farm variability in the distribution of vatA and vatE with no statistically significant differences with regards to usage. Bacterial diversity was higher in litter when probiotics or prebiotics were administered to flocks but as the litter aged, diversity decreased. No statistically signficant differences were detected in the abundance of class 1 integrons where 3%–5% of the community was estimated to harbor a copy. Abundance of pathogenic Clostridium species increased in aging litter despite the treatment while the abundance of tetracycline-resistant coliforms was unaffected by treatment. However some treatments decreased the prevalence of Salmonella. These findings suggest that withdrawing antibiotics or administering alternatives to antibiotics can change the litter bacterial community and reduce the prevalence of some pathogenic bacteria, but may not immediately impact the prevalence of antibiotic resistance.

New Health Care Delivery System and the Economics of Utilizing Veterinary Technicians

Population growth, global transformations, technological advances, and changing societal concerns on food production are inevitable and are challenging the way we produce food. Increasing global demand for animal products in the developing world, along with rapid urbanization, increasing energy costs, decreasing availability of quality arable land as well as water quality issues, place additional constraints on current food animal production systems. Indeed, the generational challenge to emerging food animal veterinary students is "how to feed the growing world without destroying the environment". The future food animal health care system and the veterinary professionals serving within will have to adapt to these changes in a manner that advances societal needs and meets demands in a responsible manner. To be relevant problem solvers in this global challenge, future veterinarians must be trained in diverse disciplines (epidemiology, management, ecology, economics, production systems, environmental sciences, nutrition) and even more importantly, have the ability to formulate integrated solutions to these complex challenges.

Industrial Food Animal Production and Global Health Risks: Exploring the Ecosystems and Economics of Avian Influenza

Many emerging infectious diseases in human populations are associated with zoonotic origins. Attention has often focused on wild animal reservoirs, but most zoonotic pathogens of recent concern to human health either originate in, or are transferred to, human populations from domesticated animals raised for human consumption. Thus, the ecological context of emerging infectious disease comprises two overlapping ecosystems: the natural habitats and populations of wild animals, and the anthropogenically controlled habitats and populations of domesticated species. Intensive food animal production systems and their associated value chains dominate in developed countries and are increasingly important in developing countries. These systems are characterized by large numbers of animals being raised in confinement with high throughput and rapid turnover. Although not typically recognized as such, industrial food animal production generates unique ecosystems—environments that may facilitate the evolution of zoonotic pathogens and their transmission to human populations. It is often assumed that confined food animal production reduces risks of emerging zoonotic diseases. This article provides evidence suggesting that these industrial systems may increase animal and public health risks unless there is recognition of the specific biosecurity and biocontainment challenges of the industrial model. Moreover, the economic drivers and constraints faced by the industry and its participants must be fully understood in order to inform preventative policy. In order to more effectively reduce zoonotic disease risk from industrial food animal production, private incentives for the implementation of biosecurity must align with public health interests.