Iterative Development of a Digital Game-Based Learning Concept: Introduction of Veterinary Herd Health Management in a Virtual Pig Herd.

A growing interest in the use of digital game-based learning has been identified in veterinary education. Projects in the development of veterinary game-based environments and scenarios are mostly initiated by veterinary institutions, faculties, or instructors; however, the process of development is complex and often involves expertise from a variety of disciplines. In the collaboration between professionals, discussions often arise about content, and how specific elements should be implemented or edited. As discussions are based on the individual experts' varied disciplines, it can be difficult to achieve a common language, and this leads to blockage and frustration in the development process. In 2012, the University of Copenhagen launched a project on digital game-based learning aimed at veterinary and agriculture students. The overall goal was to develop learning games for herd health management in pig production. The project was carried out in a collaboration between professional game developers, educational/didactic experts, and veterinarians. From early in the process, we identified a need to communicate across disciplines. Therefore, the framework of the Serious Game Development Triangle (SDT) was developed as a tool to facilitate a common language for solving complex issues. The SDT consists of three orientations: games, school, and professionalism. These three orientations are topics that are required considerations when developing a serious game that seeks to teach skills for a specific profession. The SDT contributed to improved understanding across disciplines and made the development process more progressive.

Antimicrobial prescription data in Danish national database validated against treatment records in organic pig farms and analysed for associations with lesions found at slaughter.

BACKGROUND: Antimicrobial use (AMU) in livestock is a debated topic, mainly due to the risk of associated development of antimicrobial resistance. There is focus on reducing AMU in the Danish pig production, which accounts for the largest proportion of AMU for animals in Denmark. Due to special restriction on AMU in organic pig production, the AMU in organic pig production is lower than in conventional pig production. There is concern that reduced AMU could jeopardize animal health and welfare, if it reflects insufficient treatment of sick animals, which might be reflected by the prevalence and types of lesions found at meat inspection. However, little is known about the associations between AMU and meat inspection findings in pigs from organic farms. Furthermore, excess amount of antimicrobial product after a treatment cannot be re-prescribed in organic pig herds. The initial prescription is recorded in the national database VetStat, but the unused amount is not deducted leading to uncertainty when reporting AMU. The objectives of this study were to 1) describe AMU patterns based on prescription data for organic pig production and compare with those of the conventional pig production for year 2016, 2) study the associations between herd-level AMU prescription data and meat inspection data for organic pig herds and 3) validate herd-level AMU prescription data in VetStat against treatment records collected on-farm in organic Danish pig herds. RESULTS AND CONCLUSIONS: Gastrointestinal indications account for the largest proportion of AMU in both organic pig herds (65 and 54% of treatment doses for weaners and finishers, respectively) and conventional pig herds (80 and 68% of doses for weaners and finishers, respectively). A larger proportion is prescribed for respiratory indications in organic than conventional weaners and arthropathic indications in finishers. No associations between AMU and meat inspection data were found. This needs further investigation as the prevalence of lesions at slaughter was slightly (non-significantly) higher in herds with no registered AMU than with AMU prescriptions. Only 8 out of 31 herds had recorded their AMU sufficiently detailed to compare, and using VetStat as a proxy for AMU led to 9-88% overestimation of the actual use in 7 out of these 8 herds and 120% underestimation in one herd.

The effect of New Neonatal Porcine Diarrhoea Syndrome (NNPDS) on average daily gain and mortality in 4 Danish pig herds.

BACKGROUND: The study evaluated the effect of New Neonatal Porcine Diarrhoea Syndrome (NNPDS) on average daily gain (ADG) and mortality and described the clinical manifestations in four herds suffering from the syndrome. NNPDS is a diarrhoeic syndrome affecting piglets within the first week of life, which is not caused by enterotoxigenic Escherichia coli (ETEC), Clostridium perfringens (C. perfringens) type A/C, Clostridium difficile (C. difficile), rotavirus A, coronavirus, Cystoisospora suis, Strongyloides ransomi, Giardia spp or Cryptosporidium spp. RESULTS: Piglets were estimated to have a negative ADG of 9 and 14 g when diarrhoeic for 1 day and >1 day respectively. However, if only diarrhoeic on the day of birth, no negative effect on ADG was seen. Piglets originating from severely affected litters were estimated to have a reduced ADG of 38 g. The study did not show an overall effect of diarrhoea on mortality, but herd of origin, sow parity, birth weight, and gender were significantly associated with mortality. In one of the herds, approximately 25% of the diarrhoeic piglets vs. 6% of the non-diarrhoeic piglets died, and 74% of necropsied piglets were diagnosed with enteritis. These findings indicate that the high mortality seen in this herd was due to diarrhoea. CONCLUSIONS: NNPDS negatively affected ADG in piglets, and even piglets that were diarrhoeic for one day only experienced a reduction in ADG. However, the study showed that diarrhoea restricted to the day of birth did not affect ADG and suggested this phenomenon to be unrelated to the syndrome. Since the diarrhoeal status of the litter had important effects on ADG, future research on NNPDS probably ought to focus on piglets from severely affected litters.The study showed important dissimilarities in the course of diarrhoea between the herds, and one herd was considerably more affected than the others. Within this herd, NNPDS seemed to be associated with a higher mortality, whereas in general the study did not show lethal effects of NNPDS.

Productivity parameters, antimicrobial consumption, and prevalence of enteric pathogens before and after intramuscular vaccination against Lawsonia intracellularis in naturally infected Danish weaner and finisher pig herds.

In Danish pig production, gastro-intestinal diseases account for most of the antimicrobials (AM) used in growing pigs. Diarrhoea is most frequently caused by Lawsonia intracellularis (LI), Brachyspira pilosicoli (BP), E coli fimbria type F4 (F4) and E. coli fimbria type F18 (F18). With a new LI vaccine available from 2019, it was relevant to investigate the effect of this vaccine in a Danish field study including both weaner and finisher sites. The aim was to evaluate the efficacy of Porcilis® Lawsonia Vet. in naturally LI-infected pig herds by comparing of productivity parameters, AM consumption and dynamics of enteric pathogens over two 6-months periods before and after LI vaccination. Further, faecal sock samples were collected from each site before and after vaccination and analysed by qPCR for excretion levels of LI, BP, F18 and F4. In total, 28 weaner and 41 finisher sites were included in the study. Vaccination reduced Feed Conversion Ratio by 0.12 Feed Unit/kg (p = 0.029) and 0.08 Feed Unit/kg (p = 0.005) in weaners and finishers, respectively. Increased Average Daily Weight Gain of 45.6 gr./day (p < 0.001) was found in the finishers. Mortality risk fell by 8.8% in weaners (RR = 0.912; p < 0.001). AM prescriptions for oral group treatments were reduced by 38.8% active compound/kg pig produced (p = 0.005) or 33.3% Weighted Animal Daily Doses per 100 animals per day in finishers (p = 0.004). LI prevalence was reduced in weaners and finishers (both p < 0.001) and BP prevalence was reduced in finishers (p = 0.043). Mean excretion levels of LI and BP decreased at weaner sites (-1.32 and -1.02 log(10) copies/gr faeces, respectively; both p < 0.001) and at finisher sites (-1.04 and -1.16 log(10) copies/gr faeces, respectively; both p < 0.001). Prevalence and excretion levels of F18 and F4 were unaffected by LI vaccination. In conclusion, vaccination against LI using Porcilis® Lawsonia Vet. improved productivity parameters, cut AM consumption, and reduced prevalence and excretion levels of LI and BP in naturally LI-infected pig herds.

Effect of intramuscular vaccination against Lawsonia intracellularis on production parameters, diarrhea occurrence, antimicrobial treatment, bacterial shedding, and lean meat percentage in two Danish naturally infected finisher pig herds.

Lawsonia intracellularis (LI) is an economically important enteric pathogen in pigs with a worldwide endemic prevalence. The objective of this study was to evaluate the effect of an intramuscularly administrated LI vaccine (Porcilis®Lawsonia Vet.) in Danish finisher pigs (30-115 kg) measured on key production figures, antimicrobial (AB) treatments, occurrence of diarrhea and LI shedding. The study was a group-randomized block-trial with parallel groups in two herds, Herd 1 and Herd 2, experiencing a natural subclinical-clinical LI infection in early finisher period. Vaccination occurred at weaning, but the study focused on the first eight weeks in the finisher period. Further, slaughterhouse data were included. In total, 52 and 50 finisher pens comprising 2184 and 2254 finisher pigs were included in each of two herds, respectively. LI vaccination significantly reduced feed conversion ratio (FCR) by 0.05 and 0.09 FU/kg (p = 0.007 and p < 0.001) alongside a significantly increased average daily weight gain (ADWG) by 31 and 43 gr/day (p = 0.001 and p < 0.001) in each of the herds, respectively. In the vaccinated group, less variation was found in ADWG compared to the control group (p < 0.001 in both herds) as an expression of a more uniform growth, which was further confirmed by less variation in lean meat percent in the vaccinated group in one herd (p = 0.007). No significant difference between groups were found in mortality and pigs excluded due to welfare reasons. AB flock treatment against diarrhea was significantly reduced in Herd 1 with all pens treated in the control group compared to 30.8 % in the vaccinated group (p < 0.001). In Herd 2, the difference was non-significant with 68.0 % in the control group compared to 50.0 % in the vaccination group (p = 0.252). Low levels of individual treatments against diarrhea were seen in both herds (≤ 5.0 %) but still significantly reduced in vaccinated pigs compared to control pigs (p < 0.050 in both herds). Mean diarrheic blot counts were significantly reduced in vaccinated pens compared to control pens (p < 0.001 in both herds). In vaccinated pigs, shedding of LI was reduced in both prevalence (p < 0.001 in both herds), excretion level in positive samples (p < 0.001 in both herds) and, in one herd, also in duration (p = 0.003) when compared to control pigs. In conclusion, pigs vaccinated with Porcilis®Lawsonia Vet against LI in both of two high-health and high-productive finisher herds had, compared to non-vaccinated pigs, significantly improved key production figures, and reduced AB treatment, occurrence of diarrhea, LI shedding, and growth variation.

Monitoring antimicrobial usage in companion animals: exploring the use of the Danish VetStat database.

BACKGROUND: In the Danish Veterinary Statistics Program, VetStat, sales data on medicinal products prescribed for veterinary consumption is collected. The Danish Food and Veterinary Administration (DVFA) manages the database and each purchase contains detailed product-specific information linked with a species-specific ID. National surveillance systems are also implemented or being developed in the other European Union Member States. By 2029, all Member States are required to report data on antimicrobial usage for companion animals to the European Medicines Agency. This study aimed to assess the challenges encountered when using the VetStat database to quantify antimicrobial use in Danish companion animals. Raw VetStat data were propagated by the DVFA and originated from veterinary practitioners and Danish pharmacies. RESULTS: Comprehensive estimates of antimicrobial use in Danish companion animals were not readily available due to database construct. Antimicrobials sold for use in companion animals (linked to a companion animal ID) comprised a large number of products licensed solely for horses or livestock, while data assigned a replacement code encompassed both topical and peroral antimicrobials licensed for companion animals. Additionally, antimicrobials sold from pharmacies to veterinary practitioners presented the biggest challenge in data retrieval and validation. Treatment data are only transferred to VetStat through the billing systems when Danish veterinarians are treating livestock, but not companion animals. Information on products sold for in-house use in companion animals is only available from pharmacy records without a species-specific ID. As a result, parenteral antimicrobials with multi-species authorization utilized by small animal veterinary practitioners are not accounted for in the overall estimate for companion animals. CONCLUSIONS: Owing to the database structure and requirements for data entry, antimicrobial use in companion animals is an approximation. The actual consumption may be significantly higher than what is currently calculated from the database, as the majority of parenteral products are not included. Consumption data can be measured more accurately provided treatment data from veterinary practitioners in small or mixed practices are transferred to the database through the billing system. This would equal the legal requirements for Danish veterinary practitioners treating livestock.

Prevalences and excretion levels of Lawsonia intracellularis, Brachyspira pilosicoli and Escherichia coli F4 and F18 in fecal sock samples from Danish weaner and finisher pig batches and the association with diarrhea.

BACKGROUND: Bacterial enteritis in growing pigs is a matter of concern in Danish pig production challenging herd health as well as production economy, and antimicrobial usage. The aim of this observational study using fecal sock samples was to determine the prevalence and excretion level of Lawsonia intracellularis (LI), Brachyspira pilosicoli (BP), Escherichia coli F4 (F4) and F18 (F18) and to investigate associations between prevalence or excretion levels of the bacteria and diarrhea. The study was performed in the late weaner and the early finisher period in herds with a history of diarrhea. Every weaner and finisher herd contributed with one sample each. RESULTS: In total, 47 weaner and 59 finisher herds were sampled. The overall prevalence and excretion levels (median and range in log(10) copies/gram of feces) were for LI 84.0% (median 6.2; range 3.0-7.7), for BP 45.2% (median 5.6; range 3.0-6.6), for F18 20.8% (median 5.7; range 4.7-7.7), and for F4 4.7% (median 5.5; range 5.2-6.0). In both diarrheic and non-diarrheic samples, the most prevalent bacteria were either LI alone or LI and BP in combination. In general, no association was found between increasing total bacterial excretion levels and diarrhea, but prevalence (p = 0.04) and excretion (p < 0.01) level of F18 was found to be significantly higher in diarrheic samples. Further, a significant association was found between low LI excretion level and lack of diarrhea in weaner herds (p = 0.03). A significant positive correlation was found between excretion levels of LI and BP in diarrheic weaner herd samples (p = 0.02). CONCLUSION: Enteric pathogens were prevalent in a wide range of bacterial excretion levels in both diarrheic and non-diarrheic samples. Especially LI and BP were frequently found and with a positive correlation between excretion levels. Even in the absence of diarrhea, high prevalence and excretion levels of LI and BP were detected, thus making the status of diarrhea an insufficient tool for assessing the severity of their infections.

Diagnostic performance of different fecal Lawsonia intracellularis-specific polymerase chain reaction assays as diagnostic tests for proliferative enteropathy in pigs: a review.

Traditionally, diagnosis of Lawsonia intracellularis-associated proliferative enteropathy (PE) has depended on necropsy and histology. Since the establishment of the etiologic role of L. intracellularis, a number of specific polymerase chain reaction (PCR) assays have been developed for the detection of DNA in feces. The present article is a systematic review of peer-reviewed publications on the application of L. intracellularis-specific fecal PCR as an antemortem diagnostic test for histologic lesions of PE in pigs. Based on this information, a range of diagnostic sensitivities (36-100%) and specificities (50-100%) of the published tests was calculated. Validity and confidence limits of the estimates varied considerably. The positive and negative predictive values of 6 different PCR assays were calculated for PE prevalence of 15%, 30%, 45%, 60%, 75%, and 90%, using a histologic case definition of PE and based on the reported test sensitivities and specificities. The simulated predictive values suggested that applying the fecal PCR assay as a diagnostic test is more likely to overestimate than underestimate the number of pigs having histologic lesions of PE under field conditions.

A prospective cohort study of game-based learning by digital simulation of a pig farm to train agriculture students to reduce piglet mortality.

BACKGROUND: Acquisition of knowledge and skills by agriculture students prior to real-life experience is a well-known educational challenge. Game-based learning has the advantage of being active, experiential, and problem-based, and provides immediate feedback. Simulation games are widely used in other fields to support traditional teaching methodology and actively engage students. This study investigates whether a digital pig farm game can assist agriculture students in acquiring knowledge and skills in farrowing management to reduce mortality in piglets prior to weaning. RESULTS: Overall the simulation group tended to score higher; however, at 5% confidence level, the difference was not significant. The simulation group had the lowest standard deviation which to some extent was due to reduced number of low-scoring students. Nevertheless, students requested more digital simulation for learning and practicing skills. CONCLUSION: The use of game-based learning in agricultural education has a huge potential for building skills needed on a real pig farm. However, an increase in knowledge related to farrowing management was not documented.The integration of game-based learning into an educational setting needs further evaluation.

Comparison of serum pools and oral fluid samples for detection of porcine circovirus type 2 by quantitative real-time PCR in finisher pigs.

BACKGROUND: Porcine circovirus type 2 (PCV2) diagnostics in live pigs often involves pooled serum and/or oral fluid samples for group-level determination of viral load by quantitative real-time polymerase chain reaction (qPCR). The purpose of the study was to compare the PCV2 viral load determined by qPCR of paired samples at the pen level of pools of sera (SP) from 4 to 5 pigs and the collective oral fluid (OF) from around 30 pigs corresponding to one rope put in the same pen. Pigs in pens of 2 finishing herds were sampled by cross-sectional (Herd 1) and cross-sectional with follow-up (Herd 2) study designs. In Herd 1, 50 sample pairs consisting of SP from 4 to 5 pigs and OF from around 23 pigs were collected. In Herd 2, 65 sample pairs consisting of 4 (SP) and around 30 (OF) pigs were collected 4 times at 3-week intervals. RESULTS: A higher proportion of PCV2-positive pens (86% vs. 80% and 100% vs. 91%) and higher viral loads (mean difference: 2.10 and 1.83 log(10) PCV2 copies per ml) were found in OF versus SP in both herds. The OF cut-off value corresponding to a positive SP (>3 log(10) PCV2 copies per ml) was estimated to 6.5 and 7.36 log(10) PCV2 copies per ml for Herds 1 and 2, respectively. Significant correlations between SP and OF results were found in Herd 1 (rho = 0.69) and the first sampling in Herd 2 (rho = 0.39), but not for the subsequent consecutive 3 samplings in Herd 2. CONCLUSIONS: The proportion and viral loads of PCV2 positive pens were higher in collective OF (including up to 30 pigs) compared to SP (including 4-5 pigs) of the same pens. Also, OF seemed to detect the PCV2 infection earlier with OF values just below 6.5 (Herd 1) and 7.36 (Herd 2) log(10) being associated with a negative SP for the same pen. Nevertheless, a statistically significant correlation between SP and OF could not be found for all sampling time points, probably due to a high within-pen variation in individual pig viral load becoming very evident in SP of only four or five pigs. Consequently, the results imply that OF is well suited for detecting presence of PCV2 but less so for determining the specific viral load of pigs in a pen.

Antimicrobial reduction measures applied in Danish pig herds following the introduction of the "Yellow Card" antimicrobial scheme.

Following introduction of the antimicrobial restrictive "Yellow Card Scheme" in summer 2010, a rapid decrease in the Danish national pig antimicrobial consumption was observed. The aims of this study were to (i) investigate which measures had been implemented to reduce the antimicrobial consumption according to farmers and veterinarians and (ii) where possible, investigate if said measures were reflected in the herds' antimicrobial purchase data. Based on national register data from VetStat and the Central Husbandry Register, the study population was selected among Danish pig herds which had decreased their annual antimicrobial consumption with ≥10% following the introduction of the Yellow Card Scheme comparing June 1, 2009-May 31, 2010 to June 1, 2010-May 31, 2011. Subsequently, questionnaire surveys of both farmers and veterinarians were carried out, resulting in responses from 179 farmers accounting for 202 herds (response ratio: 83%) and 58 veterinarians accounting for 140 herds. Prior to the introduction of the Yellow Card Scheme, 24% of the participating herds had an antimicrobial consumption for one or more age groups which exceeded the Yellow Card Scheme threshold values on antimicrobial consumption, while 50% of the herds had an antimicrobial consumption below the national average. The measures most frequently stated as having contributed to the antimicrobial reduction were increased use of vaccines (52% of farmers; 35% of the veterinarians), less use of group medication (44% of the farmers; 58% of the veterinarians) and staff education (22% of the farmers; 26% of the veterinarians). Reduced usage of antimicrobials for oral use accounted for 89% of the total reduction in antimicrobial use. Among the farmers, 13% also stated that change in choice of product had contributed to reducing their antimicrobial consumption. However, when analyzing purchase data, no general trend was seen towards a larger purchase of products with a higher registered dosage per kg animal compared to similar products. The findings of this study indicate that implementation of antimicrobial restrictive legislation at herd-level may lead to a variety of antimicrobial reducing initiatives in both herds with a high- and herds with a low previous level of antimicrobial consumption.

Associations between Antibacterial Treatment and the Prevalence of Tail-Biting-Related Sequelae in Danish Finishers at Slaughter.

Secondary infections as a result of tail biting cause substantial economic losses in pig production and are a subject of concern for animal welfare. The use of first-choice antibacterial agents in the treatment of tail biting in finishing pigs is hypothesized to be negatively correlated with the development of systemic infection. This would be expected to reduce the prevalence of post-mortem pyemic sequelae (such as osteomyelitis and abscesses) in finishers with tail-bite lesions. We performed a register-based study that included three Danish databases, holding information on the purchase of antibacterials at herd level (VetStat), herd demographics (Central Husbandry Register), and relevant observations at slaughter (meat inspection data). We included all finishers from indoor production finisher herds that met the inclusion criterion of at least one slaughtered finisher with a recorded tail-bite observation during 2015 at the single largest Danish abattoir. The final dataset held 1,070 herds with one or more tail-bite observations, from which 14,411 of 2,906,626 finishers (0.50%) had an individual record of a tail bite. Within this group of finishers with tail-bite observations, the recorded tail-biting-related sequelae included osteomyelitis (8.1%), abscesses in the hindquarters (10.5%), abscesses in the forequarters (2.3%), abscesses in the mid-section of the carcass (2.9%), abscesses in the limbs (2.4%), and chronic arthritis (0.5%). Due to a high-herd prevalence (>25%), osteomyelitis and abscesses in the hindquarters were selected for further analysis. The occurrence of osteomyelitis and hindquarter abscesses in individual finishers with tail-bite observations was described using a generalized linear mixed effects model with binomial response and logit link. Herd was included as a random effect, while herd size and various antibacterial treatments were tested for inclusion in the model as fixed effects. The final models indicated a significant association between herd size and both osteomyelitis (p = 0.014) and hindquarter abscesses (p < 0.001), with larger herds (2,001-12,000 registered finisher pigs) showing a reduced risk. Further, a negative association was found between the occurrence of hindquarter abscesses and the use of oral pleuromutilin (p = 0.022). The significant association with herd size highlights the potential importance of management factors in reducing the occurrence of tail-bite lesions in finishing pigs.

Reporting the national antimicrobial consumption in Danish pigs: influence of assigned daily dosage values and population measurement.

BACKGROUND: Transparent calculation methods are crucial when investigating trends in antimicrobial consumption over time and between populations. Until 2011, one single standardized method was applied when quantifying the Danish pig antimicrobial consumption with the unit "Animal Daily Dose" (ADD). However, two new methods for assigning values for ADDs have recently emerged, one implemented by DANMAP, responsible for publishing annual reports on antimicrobial consumption, and one by the Danish Veterinary and Food Administration (DVFA), responsible for the Yellow Card initiative. In addition to new ADD assignment methods, Denmark has also experienced a shift in the production pattern, towards a larger export of live pigs. The aims of this paper were to (1) describe previous and current ADD assignment methods used by the major Danish institutions and (2) to illustrate how ADD assignment method and choice of population and population measurement affect the calculated national antimicrobial consumption in pigs (2007-2013). RESULTS: The old VetStat ADD-values were based on SPCs in contrast to the new ADD-values, which were based on active compound, concentration and administration route. The new ADD-values stated by both DANMAP and DVFA were only identical for 48 % of antimicrobial products approved for use in pigs. From 2007 to 2013, the total number of ADDs per year increased by 9 % when using the new DVFA ADD-values, but decreased by 2 and 7 % when using the new DANMAP ADD-values or the old VetStat ADD-values, respectively. Through 2007 to 2013, the production of pigs increased from 26.1 million pigs per year with 18 % exported live to 28.7 million with 34 % exported live. In the same time span, the annual pig antimicrobial consumption increased by 22.2 %, when calculated using the new DVFA ADD-values and pigs slaughtered per year as population measurement (13.0 ADDs/pig/year to 15.9 ADDs/pig/year). However, when based on the old VetStat ADD values and pigs produced per year (including live export), a 10.9 % decrease was seen (10.6 ADDs/pig/year to 9.4 ADDs/pig/year). CONCLUSION: The findings of this paper clearly highlight that calculated national antimicrobial consumption is highly affected by chosen population measurement and the applied ADD-values.

Weaner production with low antimicrobial usage: a descriptive study.

BACKGROUND: Health, productivity and antimicrobial use in the production of pigs are expected to be interrelated to some extent. Previous studies on register-based data have investigated these correlations with a subsequent large variation residing at the farm level. In order to study such farm factors in more detail we designed an elaborate interview-guide. By in-depth interviews of farmers with well-managed 7-30 kg (weaner) productions we sought to describe a set of common key-factors characterizing their management practices. Identification of such common practices could be used in follow-up projects, investigating whether identified factors really are characteristic for good-practicing famers. RESULTS: Eleven farms were selected for a farm visit and in-depth interview. Participating farms used less antimicrobials than the national median (8.2 animal daily doses/100 weaners/day), had a mortality below the national average (2.9%) and an average daily weight gain above the national average (443 g/day). Similarities were observed among participating farms, including the sectioning of farms, use of all-in-all-out procedures with subsequent cleaning, purchasing 7 kg weaners from only one source, as well as active participation in management by a committed farm owner. Most farmers had a specific point of focus in their management, and were convinced that this was the reason for their success. This included; feeding, treatment strategy, refurbishment of facilities and presence in the shed. CONCLUSION: According to register data, participating farms were alike; in the good league regarding use of antimicrobials, mortality and daily growth. However, on-farm interviews elucidated more heterogeneity among farmers than expected. Most of the farmers had a specific point of focus, which they considered to be crucial for their good results. These results indicate the importance of non-registerable factors, highlighting the value of qualitative study techniques in the understanding of human actions. Further studies on the effect of various farmer types are recommended.

The new classification system for slaughter-pig herds in the Danish Salmonella surveillance-and-control program.

The Danish surveillance-and-control program for Salmonella in slaughter pigs was introduced in 1995. The key element of the program is a quick and correct identification of herds with high seroprevalence. After 5 years, the classification scheme was evaluated--and a revision was made. Data from two Salmonella screenings including a total of 1902 slaughter pig herds were used. For each herd, information was available on Salmonella status based on both microbiology and serology. Based on analyses of these data, suitable changes in the scheme were identified and their effect estimated by use of data from the Danish Salmonella Database including all herds in 2000. The classification scheme has been adjusted on the following points. (1) The sampling has been simplified into 60, 75, or 100 samples per herd per year depending on herd size. This means more-precise estimates for the seroprevalence among smaller herds. (2) Herds with an annual kill or=index 40, and the limit between Levels 2 and 3 to >or=index 70. If the Danish swine producers are interested, a Level 0 may be introduced (consisting of seronegative herds as an indication of a negligible Salmonella prevalence). The classification scheme was introduced in August 2001.

Diagnostic performance of fecal quantitative real-time polymerase chain reaction for detection of Lawsonia intracellularis-associated proliferative enteropathy in nursery pigs.

Quantitative polymerase chain reaction (qPCR) tests for detection and quantification of Lawsonia intracellularis in feces from pigs have been developed. The objective of the current study was to evaluate the diagnostic performance of a fecal qPCR test for detection of nursery pigs with L. intracellularis-associated proliferative enteropathy (PE) under field conditions. Furthermore, the diagnostic performance for different subpopulations of pigs was investigated, including pigs infected or noninfected with Porcine circovirus-2, Brachyspira pilosicoli, and Escherichia coli. The diagnostic performance was evaluated in terms of diagnostic sensitivity and specificity. Data from pigs originating from 20 herds with antibiotic treatment requiring diarrhea outbreaks from a prior study were reused. Before treatment, pigs were randomly selected for histological and immunohistochemical examination of intestinal segments and fecal quantification of L. intracellularis by qPCR. A total of 313 pigs (157 without diarrhea, 156 with diarrhea) were included in the statistical analysis, and 37 pigs (11.8%) were classified as PE positives (defined as proliferative histological lesions in combination with L. intracellularis demonstration by immunohistochemistry). Lawsonia intracellularis was detected by qPCR in feces from 91 pigs (29.1%). A nonparametric receiver operating characteristic (ROC) analysis provided an area under the ROC curve (0.93) and an optimal cutoff value of 4.8 log10 L. intracellularis bacteria/g feces. This cutoff provided a diagnostic sensitivity of 0.84 and diagnostic specificity of 0.93. The diagnostic sensitivity and specificity were significantly different between herds (P < 0.0001). Numerically, diagnostic sensitivity and specificity were different between subpopulations of pigs, but no significant differences were demonstrated.

Within-day repeatability for absolute quantification of Lawsonia intracellularis bacteria in feces from growing pigs.

Absolute quantification of Lawsonia intracellularis by real-time polymerase chain reaction (PCR) is now possible on a routine basis. Poor repeatability of quantification can result in disease status misclassification of individual pigs when a single fecal sample is obtained. The objective of the current study was to investigate overall variation within a day for fecal numbers of L. intracellularis bacteria determined by real-time PCR in growing pigs. From each of 30 pigs with an infection of L. intracellularis, 5 fecal samples were collected within 1 day. A total of 150 fecal samples were obtained and subjected to quantitative PCR (qPCR) testing. Mean fecal dry matter content was 14.3% (standard deviation = 4.5%). Two pigs (6.7%) alternated between being L. intracellularis qPCR positive and negative. For 28 pigs, the excreting levels of L. intracellularis were within the dynamic range of the qPCR assay at all sampling points. For these 28 pigs, the mean excretion level of L. intracellularis was 6.1 log(10) bacteria/g feces (standard deviation = 1.2 log(10) bacteria/g feces). The maximum observed difference between 2 fecal samples from the same pig was 1.1 log(10) bacteria/g feces. The average standard deviation for individual pigs was 0.27 log(10) bacteria/g feces. The average coefficient of variation within pigs was 0.04, ranging from 0.006 to 0.08. The results imply that absolute quantification of L. intracellularis by qPCR has acceptable repeatability within 1 day. However, a population-specific proportion of pigs alternating between positive and negative test results must be expected.

Association between average daily gain, faecal dry matter content and concentration of Lawsonia intracellularis in faeces.

BACKGROUND: The objective of this study was to investigate the association between average daily gain and the number of Lawsonia intracellularis bacteria in faeces of growing pigs with different levels of diarrhoea. METHODS: A longitudinal field study (n = 150 pigs) was performed in a Danish herd from day 29 to 47 post weaning. Every third day all pigs were weighed, subjected to a clinical examination and faecal samples were obtained. Faecal samples were subjected to dry matter determination and absolute quantification by PCR for L. intracellularis and porcine circovirus type 2 (PCV2). Association between average daily gain, faecal dry matter content, numbers of L. intracellularis bacteria and PCV2 genome copies in faeces was investigated in a multilevel mixed-effects linear model. RESULTS: Increasing numbers of L. intracellularis log10 bacteria/g faeces were significantly associated with decreasing average daily gain (P < 0.001). The association was decreasing with increasing faecal dry matter content (P < 0.01). The number of PCV2 log10 copies/g faeces was not significantly associated with average daily gain of the pigs (P > 0.5). CONCLUSION: The results suggest a potential application of a PCR quantifying L. intracellularis in growing pigs. Faecal dry matter content must be taken into consideration in interpretation of such test results.

Evaluation of a microwave method for dry matter determination in faecal samples from weaned pigs with or without clinical diarrhoea.

Microwave drying as a procedure for determination of faecal dry matter in weaned pigs was evaluated and clinical relevant cut-off values between faecal consistency scores were determined. Repeatability and reproducibility were evaluated. Overall coefficient of variation was 0.03. The 95% confidence limits for any future faecal subsample examined by any operator in any replica were ± 0.85% faecal dry matter. Robustness in relation to weight of wet faeces was evaluated. The weight categories were 0.5, 1.0, 1.5, 2.0 and 3.0 g. Samples of 0.5 g gave significantly different mean faecal dry matter content compared to weighing of 1.0-3.0 g. Agreement with freeze-drying was evaluated. Lin's concordance correlation coefficient was 0.94. On average the faecal dry matter values was 1.7% (SD=1.99%) higher in freeze dried compared to micro waved samples. Non-parametric ROC analyses were used to determine optimal faecal dry matter cut-off values for clinical faecal consistency scores. The 4 consistency scores were score 1=firm and shaped, score 2=soft and shaped, score 3=loose and score 4=watery. The cut-off values were score 1: faecal dry matter content >19.5%, score 2: faecal dry matter content ≤ 19.5% and >18.0%, score 3: faecal dry matter content ≤ 18.0% and >11.3%, score 4: faecal dry matter content ≤ 11.3%. In conclusion, the microwave procedure has an acceptable repeatability/reproducibility and good agreement with freeze drying can be expected. A minimum of 1.0 g of wet faeces must be used for analyses. Faecal dry matter cut-off values between 4 different clinical consistency scores were determined.

Observations of variable inter-observer agreement for clinical evaluation of faecal consistency in grow-finishing pigs.

Inter-observer agreement for assessment of faecal consistency in pigs was evaluated using a scoring system with 3 categories. In a pilot study, 3 observers performed an examination of faecal samples post-collection. The samples were obtained from pigs (12-13 weeks old) in 4 herds with a history of diarrhoea associated with Lawsonia intracellularis, Brachyspira spp. and/or Porcine Circovirus Type 2. Observer 1 examined all the faecal samples from the 4 herds. Observer 2 only examined the faecal samples from herds 1 and 2. Observer 3 only examined the faecal samples from herds 3 and 4. We observed a substantial agreement in faecal consistency scores between Observers 1 and 3 (kappa=0.64, 95% CI: 0.51-0.78). In contrast, only a fair agreement was observed between Observers 1 and 2 (kappa=0.24, 95% CI: 0.14-0.34). The variations in inter-observer agreement detected in the current study suggest that misclassification error can be a problem in studies assessing faecal consistency. Solutions may include developing a standardized system for scoring the consistency of pig faeces, calibration when more than one observer is involved in clinical studies and using a more objective measure of faecal consistency.