Intestinal tryptophan metabolism in disease prevention and swine production.

Tryptophan (Trp) is an essential amino acid that cannot be synthesized by animals. It has been characterized into two different isomers, levorotation-Trp (L-Trp) and dextrorotation-Trp (D-Trp), based on their distinct molecule orientation. Intestinal epithelial cells and gut microbiota are involved in metabolizing L-Trp in the gut via the activation of the kynurenine, serotonin, and indole pathways. However, knowledge regarding D-Trp metabolism in the gut remains unclear. In this review, we briefly update the current understanding of intestinal L/D-Trp metabolism and the function of their metabolites in modulating the gut physiology and diseases. Finally, we summarize the effects of Trp nutrition on swine production at different stages, including growth performance in weaned piglets and growing pigs, as well as the reproduction performance in sows.

Evaluation of different percentages of Duroc genes and gender on growth, carcass and meat quality traits for pigs.

The effect of different percentages of Duroc genes in crossbreeding (5, 50 and 100%), the gender (immunocastrated males - ICM and females) and their interaction was evaluated on growth, carcass and meat quality traits for pigs. Crossbreds (50% Duroc) had greater average daily feed intake, hot carcass weight and backfat thickness but lower meat yield when compared to 5% Duroc crossbreds and purebred (100% Duroc) animals (P < 0.05). Purebred (100% Duroc) animals had the lowest backfat thickness and subcutaneous fat thickness, and the greatest muscle depth and meat yield (P < 0.05). ICM animals had better feed conversion, greater average daily gain, hot carcass weight and amount of meat, and lower hot carcass yield, cold carcass weight, Longissimus thoracis depth, rib with belly and ham weights compared to females (P < 0.05). Marbling scores were greater in purebred (100%) animals (P < 0.05). The meat from 50% Duroc crossbreds and 100% Duroc purebred pigs was more reddish pink in color than 5% Duroc crossbreds (P < 0.05). Also, marbling scores were greater for females compared to ICM (P < 0.05). Purebred (100% Duroc) animals required more medications during production (P < 0.05).

Bioprotective potential of lactic acid bacteria for Salmonella biocontrol in vitro.

Lactic acid bacteria (LAB) are an important option for Salmonella control in animal production, resulting in lower antibiotic use. The objective of this research was to isolate LAB from meat products and from commercial probiotics sold as nutritional supplements for in vitro verification of their bioprotective potential. Eleven bacteria were identified as Pediococcus acidilactici, two as Lacticaseibacillus rhamnosus, one as Lacticaseibacillus paracasei paracasei, one as Limosilactobacillus fermentum, and one as a consortium of Lactobacillus delbrueckii bulgaricus and L. fermentum. All bacteria showed inhibitory activity against Salmonella, with emphasis on the inhibition of P. acidilactici PUCPR 011 against Salmonella Enteritidis 33SUSUP, S. Enteritidis 9SUSP, S. Enteritidis 56301, S. Enteritidis CRIFS 1016, Salmonella Typhimurium ATCC™ 14,028®, and Salmonella Gallinarum AL 1138, with inhibition halos of 7.3 ± 0.5 mm, 7.7 ± 1.0 mm, 9.0 ± 1.8 mm, 7.3 ± 0.5 mm, 7.7 ± 1.0 mm, and 7.3 ± 0.5, respectively. The isolates P. acidilactici PUCPR 011, P. acidilactici PUCPR 012, P. acidilactici PUCPR 014, L. fermentum PUCPR 005, L. paracasei paracasei PUCPR 013, and L. rhamnosus PUCPR 010 showed inhibition greater than 2 mm against at least 3 Salmonella and were used for encapsulation and in vitro digestion. The encapsulation efficiency ranged from 76.89 ± 1.54 to 116.48 ± 2.23%, and the population after 12 months of storage was from 5.31 ± 0.17 to 9.46 ± 0.09 log CFU/g. When simulating swine and chicken digestion, there was a large reduction in bacterial viability, stabilizing at concentrations close to 2.5 log CFU/mL after the analyses. The analyzed bacteria showed strong in vitro bioprotective potential; further analyses are required to determine in vivo effectiveness.

Allele-Specific Dual PCRs to Identify Members of the 27a Cluster of PPV.

Porcine Parvovirus (PPV) is one of the most important infectious agents causing severe reproductive failure in pigs. In the last two decades a particular, a novel genotype emerged in Europe and PPV-27a was named as the prototype of this genetic cluster. It was suggested that members of the PPV-27a cluster may adversely influence effective vaccination against PPV. For a reliable updated 27a definition, we aligned 93 databank-deposited partial or full nucleotide and protein sequences of the VP2 of different PPV isolates. We confirmed that the 27a cluster could indeed be distinguished from other members of the species, however, some divergences were identified compared to earlier defined genetic markers. Based on genetic differences, we developed a dual allele-specific polymerase chain reaction for the easy and quick discrimination of members of the 27a cluster from other PPV strains. The detection limit of dual PCR was found <1.66 × 104 copies/reaction. To sensitize and make it more user friendly, the method was further developed for qPCR application with fluorescent probes. Regarding the detection limit of the two PCRs (<1.66 × 104 copies/reaction of the dual PCR versus <2.40 × 102 copy/reaction of the dual qPCR), approximately two log improvement was achieved in the sensitivity of the method.

Conifer Needle Phyllosphere as a Potential Passive Monitor of Bioaerosolised Antibiotic Resistance Genes.

Monitoring antibiotic resistance genes (ARGs) is vital to the One Health approach to tackling the antibiotic resistance crisis. It has been suggested that conifer needles can be used as passive bioaerosol samplers. Here, the use of conifer needles as biomonitors of ARGs in bioaerosols was assessed as a proof-of-concept. Needles were collected from trees surrounding pig farms, villages, and forest sites in Québec, Canada. Needles were homogenised and DNA was extracted. Results of qPCR analyses showed biomass estimates were consistent across samples. Number and quantity of ARGs was significantly lower in forest sites when compared to the farm and village, comprising a distinct resistome. Consistent with previous findings, the most common ARGs were tetracyclines and sulfonamides, which were found close to agricultural activities. Although results were limited, there is great potential for using the conifer phyllosphere as a passive bioaerosol sampler. This method represents an accessible way to promote ARG surveillance over long distances from point sources.

Insights in the Development and Uses of Alternatives to Antibiotic Growth Promoters in Poultry and Swine Production.

The overuse and misuse of antibiotics has contributed to the rise and spread of multidrug-resistant bacteria. To address this global public health threat, many countries have restricted the use of antibiotics as growth promoters and promoted the development of alternatives to antibiotics in human and veterinary medicine and animal farming. In food-animal production, acidifiers, bacteriophages, enzymes, phytochemicals, probiotics, prebiotics, and antimicrobial peptides have shown hallmarks as alternatives to antibiotics. This review reports the current state of these alternatives as growth-promoting factors for poultry and swine production and describes their mode of action. Recent findings on their usefulness and the factors that presently hinder their broader use in animal food production are identified by SWOT (strength, weakness, opportunity, and threat) analysis. The potential for resistance development as well as co- and cross-resistance with currently used antibiotics is also discussed. Using predetermined keywords, we searched specialized databases including Scopus, Web of Science, and Google Scholar. Antibiotic resistance cannot be stopped, but its spreading can certainly be hindered or delayed with the development of more alternatives with innovative modes of action and a wise and careful use of antimicrobials in a One Health approach.

Prevalence, Characteristics, and Clonal Distribution of Escherichia coli Carrying Mobilized Colistin Resistance Gene mcr-1.1 in Swine Farms and Their Differences According to Swine Production Stages.

Global spread of Escherichia coli strains carrying the mobilized colistin resistance gene mcr-1.1 (MCR1-EC) poses serious threats to public health. Colistin has been generally prescribed for swine colibacillosis, having made swine farms as major reservoirs of MCR1-EC. The present study aimed to understand characteristic differences of MCR1-EC, including prevalence, antimicrobial resistance, and virulence, according to swine production stages. In addition, genetic relatedness was evaluated between MCR1-EC isolated from this study as well as pig-, human-, and chicken-derived strains published in the National Center for Biotechnology Information (NCBI), based on the multi-locus sequence types (MLSTs) and whole-genome sequences (WGS). Individual fecal samples (n = 331) were collected from asymptomatic weaning-piglets, growers, finishers, and sows from 10 farrow-to-finishing farms in South Korea between 2017 and 2019. The weighted prevalence of MCR1-EC was 11.6% (95% CI: 8.9%-15.0%, 55/331), with the highest prevalence at weaning stage. The 96.2% of MCR1-EC showed multi-drug resistance. Notably, weaning stage-derived MCR1-EC showed higher resistance rates (e.g., against extended-spectrum ß-lactams or quinolones) than those from other stages. MCR1-EC with virulence advantages (e.g., intestinal/extraintestinal pathogenic E. coli or robust biofilm formation) were identified from all pig stages, accounting for nearly half of the total strains. WGS-based in-depth characterization showed that intestinal pathogenic MCR1-EC harbored multi-drug resistance and multiple virulence factors, which were highly shared between strains isolated from pigs of different stages. The clonal distribution of MCR1-EC was shared within swine farms but rarely across farms. The major clonal type of MCR1-EC from swine farms and NCBI database was ST10-A. Core genomes of MCR1-EC isolated from individuals within closed environments (same farms or human hospitals) were highly shared (genetic distance < 0.01), suggesting a high probability of clonal expansion of MCR1-EC within closed environments such as livestock husbandry. To the best of our knowledge, this is the first study to analyze the differences in the characteristics and clonal distribution of MCR1-EC according to production stages in swine farms, an important reservoir of MCR1-EC. Our results highlight the need to establish MCR1-EC control plans in swine farms based on an in-depth understanding of MCR1-EC characteristics according to swine production stages, focusing especially on the weaning stages.

A Molecular and Epidemiological Description of a Severe Porcine Reproductive and Respiratory Syndrome Outbreak in a Commercial Swine Production System in Russia.

Porcine reproductive and respiratory syndrome (PRRS) is an economically devastating disease of swine in many parts of the world. Porcine reproductive and respiratory syndrome virus (PRRSV) type 1 is endemic in Europe, and prevalence of the subtypes differ spatially. In this study, we investigated a severe PRRS outbreak reported in 30 farms located in eastern Russia that belong to a large swine production company in the region that was also experiencing a pseudorabies outbreak in the system. Data included 28 ORF5 sequences from samples across 18 of the 25 infected sites, reverse transcriptase real-time polymerase chain reaction (RT-qPCR) results from diagnostic testing, reports of clinical signs, and animal movement records. We observed that the outbreak was due to two distinct variants of wildtype PRRSV type 1 subtype 1 with an average genetic distance of 15%. Results suggest that the wildtype PRRSV variants were introduced into the region around 2019, before affecting this production system (i.e., sow farms, nurseries, and finisher farms). Clinical signs did not differ between the variants, but they did differ by stage of pig production. Biosecurity lapses, including movement of animals from infected farms contributed to disease spread.

Connecting livestock disease dynamics to human learning and biosecurity decisions.

The acceleration of animal disease spread worldwide due to increased animal, feed, and human movement has driven a growing body of epidemiological research as well as a deeper interest in human behavioral studies aimed at understanding their interconnectedness. Biosecurity measures can reduce the risk of infection, but human risk tolerance can hinder biosecurity investments and compliance. Humans may learn from hardship and become more risk averse, but sometimes they instead become more risk tolerant because they forget negative experiences happened in the past or because they come to believe they are immune. We represent the complexity of the hog production system with disease threats, human decision making, and human risk attitude using an agent-based model. Our objective is to explore the role of risk tolerant behaviors and the consequences of delayed biosecurity investments. We set up experiment with Monte Carlo simulations of scenarios designed with different risk tolerance amongst the swine producers and we derive distributions and trends of biosecurity and porcine epidemic diarrhea virus (PEDv) incidence emerging in the system. The output data allowed us to examine interactions between modes of risk tolerance and timings of biosecurity response discussing consequences for disease protection in the production system. The results show that hasty and delayed biosecurity responses or slow shifts toward a biosecure culture do not guarantee control of contamination when the disease has already spread in the system. In an effort to support effective disease prevention, our model results can inform policy making to move toward more resilient and healthy production systems. The modeled dynamics of risk attitude have also the potential to improve communication strategies for nudging and establishing risk averse behaviors thereby equipping the production system in case of foreign disease incursions.

Stochastic Assessment of the Economic Impact of Streptococcus suis-Associated Disease in German, Dutch and Spanish Swine Farms.

The economic assessment of animal diseases is essential for decision-making, including the allocation of resources for disease control. However, that assessment is usually hampered by the lack of reliable data on disease incidence, or treatment and control measures, and that is particularly true for swine production diseases, such as infections caused by Streptococcus suis. Therefore, we deployed a questionnaire survey of clinical swine veterinarians to obtain the input data needed for a stochastic model to calculate the costs caused by S. suis, which was implemented in three of the main swine producing countries in Europe: Germany, the Netherlands and Spain. S. suis-associated disease is endemic in those countries in all production phases, though nursery was the phase most severely impacted. In affected nursery units, between 3.3 and 4.0% of pigs had S. suis-associated disease and the mortalities ranged from 0.5 to 0.9%. In Germany, the average cost of S. suis per pig (summed across all production phases) was 1.30 euros (90% CI: 0.53-2.28), in the Netherlands 0.96 euros (90% CI: 0.27-1.54), and in Spain 0.60 euros (90% CI: 0.29-0.96). In Germany, that cost was essentially influenced by the expenditure in early metaphylaxis in nursery and in autogenous vaccines in sows and nursery pigs; in the Netherlands, by expenditure on autogenous vaccines in sows and nursery pigs; and in Spain, by the expenditures in early metaphylaxis and to a lesser extent by the mortality in nursery pigs. Therefore, the differences in costs between countries can be explained to a great extent by the measures to control S. suis implemented in each country. In Spain and in Germany, use of antimicrobials, predominantly beta-lactams, is still crucial for the control of the disease.

Prevalence, Characteristics and Clonal Distribution of Extended-Spectrum ß-Lactamase- and AmpC ß-Lactamase-Producing Escherichia coli Following the Swine Production Stages, and Potential Risks to Humans.

The worldwide spread of extended spectrum ß-lactamase (ESBL)- and AmpC ß-lactamase (AmpC)-producing Escherichia coli poses serious threats to public health. Swine farms have been regarded as important reservoirs of ESBL/AmpC-EC. This study aimed to determine the prevalence, ESBL/AmpC types, and clonal distribution of ESBL/AmpC-EC from swine farms and analyze the difference according to the swine production stages. In addition, we evaluated the potential risks of swine ESBL/AmpC-EC clones to humans. Individual fecal samples (n = 292) were collected from weaning, growing, finishing, and pregnant pigs in nine swine farms of South Korea between July 2017 and March 2020. In total, 161 ESBL/AmpC-EC isolates were identified (55.1%), with the highest prevalence detected in the weaning stage (86.3%). The dominant ESBL and AmpC types were CTX-M-55 (69.6%) and CMY-2 (4.3%), respectively. CTX-M found in all production stages, while CMY was only found in growing and finishing stages. In the conjugation assay, the high transferability of CTX-M gene (55.8%) was identified, while the transfer of CMY gene was not identified. The major clonal complexes (CCs) were CC101-B1 (26.8%), CC10-A (8.7%), and CC648-F (2.9%). There was similarity in clonal distribution between different swine production stages within swine farms, estimated using the k-means analysis, which suggested a clonal transmission between the different swine stages. Among swine ESBL/AmpC-EC sequence types (STs), seven STs (ST101, ST10, ST648, ST457, ST410, ST617, and ST744) were common with the human ESBL/AmpC-EC, which registered in National Center for Biotechnology Information database. The clonal population structure analysis based on the virulence factor (VF) presented that swine ESBL/AmpC-EC clones, especially ST101-B1, harbored a highly virulent profile. In conclusion, ESBL/AmpC-EC was distributed throughout the swine production stages, with the highest prevalence in the weaning stage. The CTX-M was present in all stages, while CMY was mostly found in growing-finishing stages. The swine ESBL/AmpC-EC was identified to harbor shared clone types with human ESBL/AmpC-EC and a virulent profile posing potential risk to humans. Considering the possibility of genetic and clonal distribution of ESBL/AmpC-EC among swine production stages, this study suggests the need for strategies considering the production system to control the prevalence of ESBL/AmpC-EC in swine farms.

Seroprevalence of porcine reproductive and respiratory syndrome virus on swine farms in a tropical country of the Middle Americas: the case of Costa Rica.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses to the swine industry worldwide. Little is known regarding the epidemiology of this infection in tropical countries. To address this problem in Costa Rica, a seroepidemiological study was carried out in two phases. In the first phase, a pilot study was conducted in nine farms with the clinical diagnosis of PRRSV. In total, 265 pig serum samples were collected from animals ranging in age from 1 to 15 weeks of age. This study aimed to establish the duration of maternal immunity in piglets, to identify the period of viremia, and to determine when seroconversion occurs. In the second phase, a cross-sectional serology study was performed on a representative sample of the Costa Rican national herds in the second phase. The twenty-five selected farms represent all provinces and were classified according to herd size (100 to 2000 sows). In each farm, pigs aged 8, 10, and 12 weeks were sampled, as well as gilts based on the pilot study. In total 1281 pigs were sampled across all 25 farms. The aim of the cross-sectional study was to quantify the seroprevalence of PRRSV in Costa Rican pig farms and to describe its geographical distribution in this tropical country. The prevalence of positive farms was 44% (11/25), and these farms were located in six of the seven provinces of Costa Rica. Overall, 58% (344/596) of the pigs were seropositive to PRRSV. The age of the pigs and the ecozone where farms were located were significantly related with PRRSV seroprevalence in animals and herds, respectively.

Turnover events of animal caretakers and its impact on productivity in swine farms.

Attracting and retaining quality animal caretaking personnel is one of most pressing issues the US swine industry currently faces. On-farm employee turnover can be costly and have an impact on productivity. The primary objectives of this study were to describe the amount of animal caretaker turnover events that occurred in a single year in eleven swine farms, and to investigate associations between employee turnover events and two subsequent production parameters of interest: number of pigs weaned per sow (PWS) and pre-weaning mortality (PWM). A retrospective cohort study was conducted with eleven commercial farrow-to-wean swine farms belonging to two vertically integrated multi-site production systems within two swine production companies. Human resources and production data for the year of 2019 were obtained monthly from each farm. The primary predictor of interest was the occurrence of an employee turnover event, defined as 'voluntary' (employee decided to leave or quit) or 'involuntary' (employee was terminated by company decision). The primary outcomes of interest included the monthly average PWS and PWM. These associations were assessed with 1-, 2-, 3-, and 6-months between the turnover events and the outcome. Linear mixed effects models were fit in STATA 15, with system and farm included as random effects. To account for temporal and seasonal trends of production, season and the monthly production were included in the models. There were a total of 152 turnover events, with 4 and 148 turnover events in systems 1 and 2, respectively. The average turnover, calculated as a percent of total turnover among full time employee positions, was 92 % (SD = 62 %; Range = 8-217 %). Improved production efficiency in both monthly PWS (p = 0.01) and PWM (p = 0.02) was observed with the occurrence of an involuntary turnover event two months prior, after controlling for season, previous month production, farm, and system. For the PWS outcome, there was a significant interaction between an involuntary turnover event two months prior and monthly county-level unemployment rate (p = 0.02), indicative of the improved performance being most profound at the lowest levels of unemployment rate and diminishing at the highest levels. Turnover of animal caretaking personnel in farrow-to-wean farms was confirmed to be highly variable and high for the majority of farms in this study. Furthermore, animal caretaker turnover was associated with subsequent trends of production efficiency, warranting closer consideration of prioritizing managerial efforts in worker recruitment, training and retention.

A molecular survey reveals high occurrence of co-infections in intensive pork production farms with increased rates of mummified swine fetuses in Southern Brazil / [Pesquisa molecular revela alta ocorrência de coinfecções em granjas de produção intensiva de suínos com altas taxas de mumificação fetal no sul do Brasil]

Neste estudo, 308 amostras de fetos mumificados foram testadas para parvovírus suíno (PPV), circovírus suíno tipos 2 e 3 (PCV2 e PCV3) e leptospiras patogênicas. A idade gestacional no momento da perda gestacional e a frequência da mumificação fetal de acordo com a ordem de parto também foram investigadas. As amostras foram coletadas em granjas comerciais de criação de suínos da região sul do Brasil que apresentassem taxas de mumificação fetal igual ou maiores a 2,5%. Fragmentos de pulmão, rim, fígado e coração de fetos suínos mumificados foram coletados para análise molecular. Resultados da PCR foram classificados de acordo com a região de origem das amostras, tendo Santa Catarina, Paraná e Rio Grande do Sul contabilizado 87 (28,25%), 89 (28,90%) e 132 (42,86%) do total de amostras de fetos suínos mumificados, respectivamente. Coinfecções foram observadas na maioria dos casos e PCV3 foi o agente mais prevalente detectado, encontrado em 298 amostras (96,75%). A maioria das perdas gestacionais foi observada entre 50 e 70 dias de gestação (168; 54,5%) e a mumificação fetal não foi associada à ordem de parto das matrizes. Os achados sugerem que as altas taxas de fetos suínos mumificados na região Sul do Brasil podem ser explicadas pela infecção com esses agentes virais.(AU)

Overcoming Multidrug Resistance in Salmonella spp. Isolates Obtained From the Swine Food Chain by Using Essential Oils: An in vitro Study.

Antimicrobial resistance (AMR) is a global concern, and new approaches are needed to circumvent animal and food-borne resistant pathogens. Among the new strategies, the combination of antibiotics with natural compounds such as essential oils (EOs) could be an alternative to challenge bacterial resistance. The present study evaluates the phenotypic and genotypic antibiotic resistance of 36 Salmonella enterica (16 S. Typhimurium, 3 monophasic variant S. Typhimurium, 8 S. Enteritidis, 6 S. Rissen, 1 S. Typhi, and 2 S. Derby) strains, isolated from the swine production chain. The isolates displayed phenotypic resistance to gentamicin, amikacin, tobramycin, and tetracycline, while the resistance genes most commonly detected were parC, catA, nfsB, nfsA, blaTEM, tetA, and tetB. Then 31/36 Salmonella isolates were chosen to evaluate resistance to tetracycline and Thymus vulgaris, Eugenia caryophyllata, and Corydothymus capitatus EOs by determining minimum inhibitory concentrations (MICs). Finally, the synergistic effect between tetracycline and each EOs was evaluated by the checkerboard method, calculating the fractional inhibitory concentration (FIC) index. Among the EOs, C. capitatus displayed the best bioactivity in terms of MICs, with the lowest values (0.31 and 0.625 µl/ml). On the contrary, the strains showed the ability to grow in the presence of the maximum concentration of tetracycline employed (256 µg/ml). While not displaying a real synergism according to the FIC index, the combination of tetracycline compounds and the three EOs resulted in a significant reduction in the MIC values to tetracycline (4 µg/ml), suggesting a restoration of the susceptibility to the antibiotic in Salmonella spp.

Association between different types of within-farm worker movements and number of pigs weaned per sow in U.S. Swine farms.

The integration and intensification of modern swine production has amplified the importance of biosecurity, as diseases are more easily able to spread and persist in large swine farms, resulting in economic losses. Advancements in accessible technology and computational methods offer new applications for precision livestock farming, such as monitoring internal movements to better understand biosecurity compliance on farm. In this study, a beacon-sensor based internal movement system (PigChamp Pro Europa®) was utilized to investigate the association between weekly within-farm movements of workers and an important production parameter: average weekly number of pigs weaned per sow (PWS), on three US swine farms. Sensors were installed in each room of each farm and Bluetooth-based beacons were distributed individually to farm employees. Movement data was collected for approximately one year and production data was extracted from each farm retrospectively. A linear mixed effects model was fit in STATA 15 with the primary outcome as the average weekly number of pigs weaned per sow and farm included as a random effect. The main predictors included the weekly frequency of three movement types thought to be risky with respect to disease transmission and maintenance in the herd. The frequency values of the three movements were categorized based on the tertile values for each farm. The movement with the highest average frequency was between farrowing rooms for all three farms. The medium frequency of movements category between farrowing rooms the two-weeks preceding the outcome was significantly associated with a decrease in PWS by nearly 1-pig for every 5-sows after controlling for farm, pre-weaning mortality, PWS the week prior, and season (p = 0.03). The random effect variance estimate for the model was 0.21 with a standard error of 0.18. The intraclass correlation coefficient was 0.67 with a standard error of 0.19, indicating that 67% of the unexplained variability in PWS could be attributed to the farm level. This study demonstrates the application of beacon-sensor technology to monitor internal personnel movements in swine production. Technological applications to monitoring trends of within farm movements of farm personnel, such as the system used here, may have the potential to identify specific movements related to farm-specific biosecurity protocol allowing corrective measures and facilitating focused efforts on disease control and mitigation; in turn maintaining productivity and improving overall animal health.

Methacholine induced airway contraction in porcine precision cut lung slices from indoor and outdoor reared pigs.

Repetitive exposure to bioaerosols in swine production facilities (SPF) promotes respiratory dysfunction in workers and animals. An adequate understanding of the impact of the SPF environment on pulmonary physiology is needed. However, there is currently no sufficient ex vivo model to investigate the cause for agriculture-related lung disease. The precision cut lung slices (PCLS) technique represents a practical and useful procedure for ex vivo studies. Our goal was to use the PCLS technique to develop a model of agriculture-related lung diseases using a physiologically relevant animal model, the domesticated pig. Freshly prepared pig lung tissue cores were sectioned into 300 µm slices and viability was measured by lactate dehydrogenase activity and live/dead staining. Airway contractility in response to a methacholine (MCh) dose gradient (10-7-10-4 M) was measured. After the last MCh dose, PCLS were incubated with 1 mM chloroquine to allow airways to relax. Time-lapse images were taken every minute for 35 minutes and used to determine airway lumen area changes. Porcine PCLS remained viable and demonstrated metabolic activity for three days. PCLS from indoor and outdoor pigs contracted in response to MCh exposure and relaxed when incubated with chloroquine. Notably, PCLS of indoor pigs showed greater airway constriction in response to 10-5 M MCh exposure compared to outdoor pig PCLS (P<0.05). These data suggest that exposure to the indoor pig production environment may be associated with hyperresponsiveness in swine airways, and support future studies to investigate lung response to inflammatory substances using the porcine PCLS model.

Sludge management in anaerobic swine lagoons: A review.

Sludge is nutrient and mineral rich residue of anaerobic treatment that is often utilized as a fertilizer. Sludge management is crucial to maintain the function of anaerobic treatment lagoons and ensure efficient nutrient utilization. Intensive livestock production has resulted in accumulation of sludge residue in regions where nutrients are in surplus. This situation adversely impacts the sustainability of livestock production. Alternative uses of sludge needs to be developed and adopted to reduce the negative impacts associated with the nutrients accumulation on farms and nearby crop fields. A thorough understanding of sludge composition is necessary to identify appropriate end use. This review explores swine lagoon sludge (SLS) in relation to its composition, sampling techniques, management approaches, fertilizer value, challenges and opportunities for further development.