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Lessons learned from managing electronic sow feeders and collecting weights of gestating sows housed on a large commercial farm
Abstract
An observational study was conducted on a commercial 5600-sow farm using electronic sow feeders (ESF) to collect daily feed intake and scales to obtain sow body weights. The challenges that emerged during this study and proposed solutions may be useful for future research projects in commercial farms with ESF feeding systems. A total feed delivery per day was reported for females, regardless of how many times they may have entered the feeding station. It would be valuable to obtain records for individual feeding events to determine how many times females entered the feeding stations and if it was a feeding or non-feeding event. In this system, there was wide variation in daily sow weights because they entered the feeding station several times a day. Discrepancies in individual body weight were found to be attributed to the speed a sow moved across the scale, long scale length, and interference with the scale antenna. Possible solutions include adding panels before and after the scale, reducing scale length, and careful placement of the antenna. Nevertheless, combining the feeding of gestating sows via ESF with daily weight collection has the potential to generate valuable data sets. © 2018 American Association of Swine Veterinarians. All rights reserved.
... PLF technologies enable continuous monitoring and data collection, which can significantly increase productivity on US farms. For example, Electronic Sow Feeder (ESF) allows for precise feeding on the basis of individual animal needs, leading to improved feed conversion rates and overall productivity (Dritz et al., 2018). A survey indicated that 57% of US pig farmers intend to adopt PLF technologies in the future, recognizing their potential to increase productivity and reduce costs (Kopler et al., 2023). ...
This study aimed to review the recent development of different technologies in precision livestock farming (PLF), along with their scopes and challenges. PLF is an innovative, contemporary, and fast-expanding approach to agriculture that aims to improve sustainable livestock farming. The growing global population has increased the demand for animal products. To meet this demand, farmers have to increase their production, so without the integration of precision technology, this cannot be achieved. PLF currently employs a variety of technologies. Some of these methods include vision-based solutions, load cells, accelerometers, microphones, thermal cameras, photoelectric sensors, and radio-frequency identification (RFID). Despite the availability of different PLF technologies, their adoption by farmers varies widely on the basis of the cost of investment, ease of operation, availability, and accessibility. These technologies are used to track different activities of livestock farming, such as feeding, drinking, physical behavior, temperature regulation, tracking and identification, estrus detection, disease detection, and milking. PLF contributes significantly to technological advancement, human-animal relationships, environmental sustainability, and increased productivity. It does, however, present a number of obstacles and eventual advantages.
... Groenlo, the Netherlands) was used to identify sows consuming less than 50% of their daily feed allocation at 10 AM each day before the system reset. These sows were then assisted in accessing the electronic sow feeders to give them another opportunity to consume their full daily feed allotment [22,23]. Sows were kept in the group-housed system from 1 to 109 days of gestation, then moved to the free-farrowing house about 7 days before farrowing. ...
Objective:
The current study investigated the impacts of different feeding regimes during early gestation on conception rate, litter traits, piglet birthweight, and litter uniformity in primiparous sows.
Methods:
In total, 108 primiparous sows were inseminated and assigned to either a standard (1.9±0.5 kg/day, S) or high (2.9±0.8 kg/day, H) feeding levels during the first 35 days of gestation. The feeding regimes were categorized based on periods of gestation: 1 to 3, 4 to 15, and 16 to 35 days, resulting in four groups: SSS (n=26), SSH (n=28), SHH (n=28), and HHH (n=26). Afterwards, sows were placed into a group-housed system equipped with electronic sow feeders. The sows were weighed and assessed for backfat thickness and loin muscle depth at 0 and 35 days of gestation. At farrowing, data were collected on the total number of piglets born per litter (TB), piglet birthweights, and the coefficient of variation of piglet birthweights.
Results:
On average, sows gained 22.5±21.6 kg during the first 35 days of gestation, showing a positive correlation with backfat gain (r=0.954, p=0.006). The backfat gain in the HHH group was higher than in the SSS (p=0.016) and the SSH groups (p=0.023), but did not differ from the SHH group (p=0.684). Conception rates did not show differences among the feeding regimes (p>0.05). Individual piglet birthweights in the HHH group were higher than those in the SSH group (p<0.001). Likewise, the percentage of piglets with birthweights <1000 g in the HHH group was lower than that in the SSH group (p<0.001). However, the variation of piglet birthweight did not differ among the groups (p>0.05).
Conclusion:
Increasing feeding levels in primiparous sows in a group-housed system during early pregnancy can effectively restore their body condition without any detrimental effects on subsequent litters.
... In the scientific literature, there is a conspicuous absence of data communication of ESFs in large-scale gestation units using stalls. In a study involving the use of the feeding station Nedap Velos, conducted by Thomas et al. [44], a significant challenge arose-feed intake data had to be manually extracted on a daily basis due to the lack of long-term data storage capabilities. Additionally, the study reported instances of lost RFID tags in group housing, resulting in potential inaccuracies in data recording. ...
To obtain good productive performance, sows have different nutrition requirements at different gestation periods. However, in gestation stalls, conventional feeders have large relative errors, management is difficult because of the large numbers of sows, and there are shortcomings in feeding precision and data management. In order to achieve precision feeding and enhance the control of multiple feeders for gestating sows housed in stalls, this study was carried out to investigate a precision feeding system that could be controlled at multiple levels. This system consisted of an electronic sow feeder (ESF), controller area network (CAN), personal digital assistant (PDA), central controller, and Internet of Things platform (IoTP). The results of the experiment showed that relative errors of 60 ESFs delivering feed were within ±2.94%, and the coefficient of variation was less than 1.84%. When the received signal strength indicator (RSSI) ranged from −80 dbm to −70 dbm, the packet loss rate of the PDA was 3.425%. When the RSSI was greater than −70 dbm, no packet loss was observed, and the average response time was 556.05 ms. The IoTP was at the performance bottleneck when the number of concurrent threads was greater than 1700. These experimental results indicated that the system was not only highly accurate in delivering feed, but was also highly reliable in the transmission of information, and therefore met the production requirements of an intensive gestation house.
... Pour les truies gestantes, il existe principalement deux types de systèmes d'alimentation : (i) les systèmes d'alimentation en simultané permettent de distribuer l'aliment à toutes les truies d'une même salle en même temps, une à deux fois par jour. Cette distribution peut se faire individuellement lorsque les truies sont logées en cases individuelles, ou collectivement lorsque les truies sont élevées en groupe ; (ii) les systèmes d'alimentation séquentiels permettent la distribution individualisée de l'aliment, les truies venant successivement se nourrir dans un dispositif d'alimentation automatisée, appelé Distributeur Automatique de Concentrés (DAC) (Thomas et al., 2018). Ces dispositifs sont généralement associés à une En maternité, les truies disposent d'une auge individuelle pour la réception d'un aliment dont la composition est généralement identique tout au long de la lactation. ...
L'utilisation des ressources alimentaires est au cœur des enjeux de durabilité de l'élevage porcin. Cette thèse présente les différentes étapes de construction d'un système d'aide à la décision pour l'alimentation individualisée et en temps réel des truies en lactation, suivies de son évaluation en élevage. Sa construction s'appuie sur une approche de modélisation des besoins nutritionnels à l'échelle de l'individu, combinée à différentes approches d'apprentissage par machine learning, pour la prédiction des paramètres nécessaires au calculs des besoins. L'utilisation du système en temps réel s'appuie sur des données sur la truie et sa portée, aujourd'hui accessibles à haut débit en élevage. Les besoins nutritionnels pour la production de lait peuvent être prédits par des algorithmes d'apprentissage supervisés, à partir d'un nombre restreint d'attributs.Concernant la consommation alimentaire, facteur important pour la détermination de la composition de la ration, la méthode de prédiction proposée s'appuie sur un apprentissage non-supervisé par clustering de données collectées en temps réel en élevage à l’aide d’un automate de distribution. Testé en élevages, ce dispositif permet d'atteindre des performances zootechniques très proches des systèmes d'alimentation conventionnels, tout en réduisant significativement les apports de protéines, l’excrétion d’azote et de phosphore et le coût alimentaire et en améliorant la couverture des besoins nutritionnels à l'échelle individuelle.
... Each pen was equipped with a scale (1.74 m long  1. 07 m wide, Nedap Velos, Gronelo, Netherlands) located in the alleyway. As sows left the feeding station, they walked across a scale and weight was recorded (Thomas et al., 2018a). ...
Limited information is available on lysine requirement estimates of modern, high-producing gestating sows Therefore, the objective of this study was to evaluate the effects of increasing standardized ileal digestible (SID) lysine during gestation on piglet birthweight and reproductive performance of gilts and sows. A total of 936 females (498 gilts, 438 sows; Camborough®, PIC, Hendersonville, TN) were group-housed (approximately 275 females per pen) and individually fed with electronic sow feeders. Females were moved from the breeding stall to pens on d 4 of gestation and allotted to one of four dietary treatments on d 5. Dietary treatments included increasing SID lysine intake (11.0, 13.5, 16.0, and 18.5 g/d). Gilts (parity 1) and sows (parity 2+) received 2.1 and 2.3 kg (22.2 and 24.3 MJ net energy per day) of feed throughout the entire gestation period, respectively. Dietary treatments were achieved by different blends of low (0.48% SID lysine) and high (0.88% SID lysine) lysine diets, prepared by changing the amount of corn and soybean meal in these two diets. Female weight and backfat were recorded on d 4 and 111 of gestation. Individual piglet weight was obtained within 12 h of birth on litters from 895 females. Final weight, and calculated maternal BW, body lipid, and body lean at d 111 of gestation increased (linear, P
... A gilt training program is designed to allow gilts to become familiar with the ESF system prior to breeding. In this production system, gilts receive 2 wk of training prior to breeding and being placed in gestation group housing as described by Vier et al. (2016) and Thomas et al. (2018a). The data indicate that even with extensive training, parity 1 sows were reluctant to consume the full feed allowance and remain at full feed for the course of gestation. ...
The effects of parity and stage of gestation on female growth criteria, and reproductive performance were evaluated on a commercial sow farm. A total of 712 females (Camborough®, PIC, Hendersonville, TN) were group-housed and individually fed with electronic sow feeders. Gilts (parity 1) and sows were offered 2.0 and 2.26 kg of feed per day (4.7 and 5.3 Mcal NE per d), respectively. Females were moved from the breeding stall to pens on d 5 of gestation. A scale was located in the alleyway after sows left individual feeding stations. Feed intake and BW were recorded daily throughout gestation generating values for ADFI, ADG, and G:F for each sow. Data was divided into 3 parity groups: 1, 2, and 3+ and gestation was divided into 3 periods: d 5 to 39, 40 to 74, and 75 to 109. From d 5 to 39, ADFI was decreased (P < 0.05) for parity 3+ sows compared to the other periods of gestation. Parity 2 sows, although provided the same feed allowance, had greater (P < 0.05) ADFI during the first period of gestation than parity 3+ sows. Parity 1 and 2 sow ADG increased (P < 0.05) from d 39 to 74 of gestation, then decreased (P < 0.05) from d 74 to 109 of gestation. Parity 3+ sow ADG increased (P < 0.05) in each subsequent period of gestation. Parity 1 sows had the greatest (P < 0.05) ADG in comparison to parity 2 and 3+ sows in each period of gestation. Regardless of parity group, G:F was poorest (P < 0.05) from d 5 to 39 of gestation compared with sequential periods of gestation. Parity 1 sow G:F was greater (P < 0.05) than parity 2 and 3+ sows for all periods of gestation. Backfat gain indicated that parity 1 sows maintained backfat (approximately 18 mm) while parity 2 and 3+ sows gained (P < 0.05) approximately 1 mm backfat throughout gestation. Total born was greatest (P < 0.05) for parity 3+ sows with parity 1 sows marginally greater (P < 0.10) than parity 2 sows. Although there was statistical evidence (P < 0.001) for a positive correlation between BW gain and total born in parities 1 (r = 0.23; P = < 0.001), 2 (r = 0.15; P = 0.035), and 3+ (r = 0.29; P < 0.001), these correlations are very weak. Overall, this study indicates that parity 1 sows have the greatest G:F in gestation and that there is a lack of evidence for strong correlations between feed intake, growth, and reproductive performance.
The objective of this study was to model daily standardized ileal digestible (SID) Lys requirements in gestating sows. Data from 877 females (459 gilts, 418 sows; Camborough®, PIC, Hendersonville, TN) was collected and modeled using Dourmad et al. (2008) equations. Individual feed intake and body weight (BW) were recorded daily throughout gestation. Dietary treatments included 11, 13.5, 16, and 18.5 g/d SID Lys intake throughout gestation. Data were divided into 2 parity groups: gilts and sows, and gestation was divided into 3 stages: d 5 to 39 (early), 40 to 74 (mid), and 75 to 108 (late). The model follows the principle that energy is partitioned between maintenance, growth of conceptus (fetus, placenta, and fluids), and maternal protein and lipid deposition. Requirements for SID Lys were estimated based on predicted whole body protein deposition. After dividing energy requirements into tissue pools for maintenance, products of conceptus, and maternal reserves, the greatest portion of the energy requirement was for maintenance. Estimated protein retention of the conceptus increased in each sequential stage of gestation (P < 0.05) but there were no differences (P > 0.05) among treatments. Regardless of parity or stage of gestation, increasing SID Lys increased estimated maternal protein deposition (linear, P < 0.001), but it decreased in each sequential stage of gestation (P < 0.001). Estimated maternal lipid deposition increased with increasing SID Lys (linear, P = 0.076) and decreased in each sequential stage of gestation (P < 0.05), with gilts having to mobilize maternal lipid in late gestation. For gilts and sows, estimated SID Lys requirements increased in each sequential stage of gestation (P < 0.05). Estimated SID Lys balance (SID Lys intake - SID Lys requirement) increased with increasing SID Lys in the diet (quadratic, P < 0.054), and decreased (P < 0.05) in each sequential stage of gestation. Overall, the model shows how changes in protein retention of the conceptus and maternal protein deposition differ by parity and stage of gestation for a single gestation phase. Based on predicted changes in protein deposition, and SID Lys balance, providing females with 11.0 g/d SID Lys throughout gestation adequately meets Lys requirements for most of gestation; however, gilts and sows were in a negative SID Lys balance for the last 5- to 10 d of gestation and this can be prevented by providing gilts and sows with 13.5 g/d SID Lys.
Animal facilities are increasing in size, while the availability of skilled workers is decreasing, thus, making it difficult for the farm laborers to ensure the health and well-being of all animals under their care. Passive Radio Frequency Identification (RFID) systems have been successfully used in animal facilities and research has identified potential applications in behavior monitoring for automated illness detection. While RFID signals range in frequency from 9 kHz to 5.8 GHz, the three most common frequencies are Low Frequency (LF, 125 kHz or 134.2 kHz), High Frequency (HF, 13.56 MHz), and Ultra-High Frequency (UHF, 865-868 MHz or 902-928 MHz). The objective of this article is to compare and evaluate the application of these three different RFID systems within large research facilities for livestock and poultry in terms of hardware characteristics, system design, and data processing and usage. Differences in tag construction, availability and cost are evident, but also basic differences in reader and antenna function, such as physics of communication, speed of detection, and anti-collision procedures exist. The systems have significant differences in reading ranges and are known to have varying influence of materials, especially water and metal, on the performance of the systems. However, the data streams, as well as methods of data processing and the creation of events (e.g., visits to a feeder), are similar for all systems. The characteristics mentioned do not necessarily identify an ideal RFID technology but reveal positive and negative aspects of each system. The three different RFID systems have been successfully applied in livestock and poultry facilities. Current research is focused on the utilization of the RFID data in prediction and decision models for illness, animal welfare, and management actions. Keywords: Behavior, Cattle, Frequency ranges, Health and welfare, Poultry, Swine, Transponder.
The ontogeny of PRRSV antibody in oral fluids has been described using isotype-specific ELISAs. Mirroring the serum response, IgM appears in oral fluid by 7 days post inoculation (DPI), IgA after 7 DPI, and IgG by 9 to 10 DPI. Commercial PRRSV ELISAs target the detection of IgG because the higher concentration of IgG relative to other isotypes provides the best diagnostic discrimination. Oral fluids are increasingly used for PRRSV surveillance in commercial herds, but in younger pigs, a positive ELISA result may be due either to maternal antibody or to antibody produced by the pigs in response to infection. To address this issue, a combined IgM-IgA PRRSV oral fluid ELISA was developed and evaluated for its capacity to detect pig-derived PRRSV antibody in the presence of maternal antibody. Two longitudinal studies were conducted. In Study 1 (modified-live PRRS vaccinated pigs), testing of individual pig oral fluid samples by isotype-specific ELISAs demonstrated that the combined IgM-IgA PRRSV ELISA provided better discrimination than individual IgM or IgA ELISAs. In Study 2 (field data), testing of pen-based oral fluid samples confirmed the findings in Study 1 and established that the IgM-IgA ELISA was able to detect antibody produced by pigs in response to wild-type PRRSV infection, despite the presence of maternal IgG. Overall, the combined PRRSV IgM-IgA oral fluid ELISA described in this study is a potential tool for PRRSV surveillance, particularly in populations of growing pigs originating from PRRSV-positive or vaccinated breeding herds.
Background
The study highlights the shedding pattern of Senecavirus A (SVA) during an outbreak of vesicular disease in a sow farm from the South-central Minnesota, USA. In this study, 34 individual, mixed parity sows with clinical signs of vesicular lesions and 30 individual piglets from 15 individual litters from sows with vesicular lesions were conveniently selected for individual, longitudinal sampling. Serum, tonsil, rectal, and vesicular swabs were collected on day1 post outbreak, and then again at 1, 2, 3, 4, 6, and 9 weeks post outbreak. Samples were tested at the University of Minnesota Veterinary Diagnostic Laboratory for SVA via Real Time Polymerase Chain Reaction (RT-PCR)
Results
In sows, vesicular lesions had the highest concentration of SVA, but had the shortest duration of detection lasting only 2 weeks. Viremia was detected for 1 week post outbreak, and quickly declined thereafter. SVA was detected at approximately the same frequency for both tonsil and rectal swabs with the highest percentage of SVA positive samples detected in the first 6 weeks post outbreak. In suckling piglets, viremia quickly declined 1 week post outbreak and was prevalent in low levels during the first week after weaning (4 weeks post outbreak) and was also detected in piglets that were co-mingled from a SVA negative sow farm. Similar to sows, SVA detection on rectal and tonsil swabs in piglets lasted approximately 6 weeks post outbreak.
Conclusion
The study illustrates the variation of SVA shedding patterns in different sample types over a 9 week period in sows and piglets, and suggests the potential for viral spread between piglets at weaning.
Introduction
The prevention and control of Actinobacillus pleuropneumoniae in commercial production settings is based on serological monitoring. Enzyme-linked immunosorbent assays (ELISAs) have been developed to detect specific antibodies against a variety of A. pleuropneumoniae antigens, including long-chain lipopolysaccharides (LPS) and the ApxIV toxin, a repeats-in-toxin (RTX) exotoxin unique to A. pleuropneumoniae and produced by all serovars. The objective of this study was to describe ApxIV antibody responses in serum and oral fluid of pigs.
Material and Methods
Four groups of pigs (six pigs per group) were inoculated with A. pleuropneumoniae serovars 1, 5, 7, or 12. Weekly serum samples and daily oral fluid samples were collected from individual pigs for 56 days post inoculation (DPI) and tested by LPS and ApxIV ELISAs. The ApxIV ELISA was run in three formats to detect immunlgobulins M, G, and A (IgM, IgG and IgA) while the LPS ELISA detected only IgG.
Results
All pigs inoculated with A. pleuropneumoniae serovars 1 and 7 were LPS ELISA serum antibody positive from DPI 14 to 56. A transient and weak LPS ELISA antibody response was observed in pigs inoculated with serovar 5 and a single antibody positive pig was observed in serovar 12 at ≥35 DPI. Notably, ApxIV serum and oral fluid antibody responses in pig inoculated with serovars 1 and 7 reflected the patterns observed for LPS antibody, albeit with a 14 to 21 day delay.
Conclusion
This work suggests that ELISAs based on ApxIV antibody detection in oral fluid samples could be effective in population monitoring for A. pleuropneumoniae.
Background
The usefulness of oral fluid (OF) sampling for surveillance of infections in pig populations is already accepted but its value as a tool to support investigations of porcine respiratory disease complex (PRDC) has been less well studied. This study set out to describe detection patterns of porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2), swine influenza virus type A (SIV) and Mycoplasma hyopneumoniae (M. hyo) among farms showing differing severity of PRDC.
The study included six wean-to-finish pig batches from farms with historical occurrence of respiratory disease. OF samples were collected from six pens every two weeks from the 5th to the 21st week of age and tested by real time PCR for presence of PRRSV, SIV and M. hyo and by quantitative real time PCR for PCV2. Data was evaluated alongside clinical and post-mortem observations, mortality rate, slaughter pathology, histopathology, and immunohistochemistry testing data for PCV2 antigen where available.
Results
PRRSV and M. hyo were detectable in OF but with inconsistency between pens at the same sampling time and within pens over sequential sampling times. Detection of SIV in clinical and subclinical cases showed good consistency between pens at the same sampling time point with detection possible for periods of 2–4 weeks. Quantitative testing of OF for PCV2 indicated different patterns and levels of detection between farms unaffected or affected by porcine circovirus diseases (PCVD). There was good correlation of PCR results for multiple samples collected from the same pen but no associations were found between prevalence of positive test results and pen location in the building or sex of pigs.
Conclusions
Detection patterns for PRRSV, SIV and M. hyo supported the effectiveness of OF testing as an additional tool for diagnostic investigation of PRDC but emphasised the importance of sampling from multiple pens and on multiple occasions. Preliminary evidence supported the measurement of PCV2 load in pooled OF as a tool for prediction of clinical or subclinical PCVD at farm level.
Formulas and software for calculating sample size for surveys based on individual animal samples are readily available. However, sample size formulas are not available for oral fluids and other aggregate samples that are increasingly used in production settings. Therefore, the objective of this study was to develop sampling guidelines for oral fluid-based porcine reproductive and respiratory syndrome virus (PRRSV) surveys in commercial swine farms. Oral fluid samples were collected in 9 weekly samplings from all pens in 3 barns on one production site beginning shortly after placement of weaned pigs. Samples (n = 972) were tested by real-time reverse-transcription PCR (RT-rtPCR) and the binary results analyzed using a piecewise exponential survival model for interval-censored, time-to-event data with misclassification. Thereafter, simulation studies were used to study the barn-level probability of PRRSV detection as a function of sample size, sample allocation (simple random sampling vs fixed spatial sampling), assay diagnostic sensitivity and specificity, and pen-level prevalence. These studies provided estimates of the probability of detection by sample size and within-barn prevalence. Detection using fixed spatial sampling was as good as, or better than, simple random sampling. Sampling multiple barns on a site increased the probability of detection with the number of barns sampled. These results are relevant to PRRSV control or elimination projects at the herd, regional, or national levels, but the results are also broadly applicable to contagious pathogens of swine for which oral fluid tests of equivalent performance are available.
We evaluated the use of oral fluid as an alternative to serum samples for Classical swine fever virus (CSFV) detection. Individual oral fluid and serum samples were collected at different times post-infection from pigs that were experimentally inoculated with CSFV Alfort 187 strain. We found no evidence of CSFV neutralizing antibodies in swine oral fluid samples under our experimental conditions. In contrast, real-time reverse transcription-polymerase chain reaction could detect CSFV nucleic acid from the oral fluid as early as 8 d postinfection, which also coincided with the time of initial detection in blood samples. The probability of CSFV detection in oral fluid was identical or even higher than in the corresponding blood sample. Our results support the feasibility of using this sampling method for CSFV genome detection, which may represent an additional cost-effective tool for CSF control.
Influenza A virus (IAV) is economically important in pig production and has broad public health implications. In Europe, active IAV surveillance includes demonstration of antigen in nasal swabs and/or demonstration of antibodies in serum (SER) samples; however, collecting appropriate numbers of individual pig samples can be costly and labour-intensive. The objective of this study was to compare the probability of detecting IAV antibody positive populations using SER versus oral fluid (OF) samples. Paired pen samples, one OF and 5–14 SER samples, were collected cross-sectional or longitudinally. A commercial nucleoprotein (NP)-based blocking ELISA was used to test 244 OF and 1004 SER samples from 123 pens each containing 20–540 pigs located in 27 UK herds. Overall, the IAV antibody detection rate was higher in SER samples compared to OFs under the study conditions. Pig age had a significant effect on the probability of detecting positive pens. For 3–9-week-old pigs the probability of detecting IAV antibody positive samples in a pen with 95% confidence intervals was 40% (23–60) for OF and 61% (0.37–0.80) for SER (P = 0.04), for 10–14-week-old pigs it was 19% (8–40) for OF and 93% (0.71–0.99) for SER (P < 0.01), and for 18–20-week-old pigs it was 67% (41–85) for OF and 81% (0.63–0.91) for SER (P = 0.05). Collecting more than one OF sample in pens with more than 25 less than 18-week-old pigs should be further investigated in the future to elucidate the suitability of OF for IAV surveillance in herds with large pen sizes.
Background
Porcine reproductive and respiratory syndrome virus (PRRSV) is the causative agent of an economically important disease in swine. Since it has been shown that PRRSV and PRRSV specific antibodies can be detected in oral fluid, many different aspects have been studied to show that oral fluid could be a worthy alternative diagnostic sample to serum for monitoring and surveillance of this disease. Thorough field evaluations are however missing to convincingly show its usefulness under representative field conditions.
Methodology
Pen-based oral fluid samples and serum samples from all individual pigs in the corresponding pens were collected from post-weaning pigs of three different age categories in eight endemically PRRSV infected farms and one PRRSV free farm in Belgium. All samples were tested by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and ELISA to detect PRRSV RNA and PRRSV specific antibodies, respectively.
Results
While the relative specificity of PRRSV detection by qRT-PCR in pen-based oral fluid compared to serum collected from individual pigs was high in all age categories (>90%), the relative sensitivity decreased with the age of the pigs (89, 93 and 10% in 8-12w, 16-20w and 24-28w old pigs, respectively). The latter correlated with a lower percentage of PRRSV positive pigs in serum/pen in the different age categories (55, 29 and 6%, respectively). Irrespective of the age category, pen-based oral fluid samples were always found PCR positive when at least 30% of the individual pigs were positive in serum. PRRSV specific antibody detection in oral fluid by ELISA showed a 100% relative sensitivity to detection in serum since oral fluid samples were always positive as soon as one pig in the pen was positive in serum. On the other hand, two false positive oral fluid samples in 11 pens without serum positive pigs were found, resulting in a relative specificity of 82%. Indications are however present that the oral fluid result indicated the correct infection status but the absence of a golden standard test makes it difficult to define definitive test characteristics.
Conclusions
Overall it can be concluded that oral fluid seems to be a useful matrix for diagnosis of PRRSV under field conditions and that differences in kinetics of PRRSV and PRRSV specific antibody detection in oral fluid and serum of individual pigs can also be reflected in pen-based oral fluid results.
Sampling guidelines were developed by observing pigs during oral-fluid sample collec-tion in commercial herds. Pigs with previous oral-fluid collection experience ("trained") should be allowed 20 minutes access to the rope. Pigs with no prior experience ("untrained") should be allowed 60 minutes. One collection is enough to train pigs.
Background:
The lack of seasonality of swine influenza A virus (swIAV) in combination with the capacity of swine to harbor a large number of co-circulating IAV lineages, resulting in the risk for the emergence of influenza viruses with pandemic potential, stress the importance of swIAV surveillance. To date, active surveillance of swIAV worldwide is barely done because of the short detection period in nasal swab samples. Therefore, more sensitive diagnostic methods to monitor circulating virus strains are requisite.
Methods:
qRT-PCR and virus isolations were performed on oral fluid and nasal swabs collected from individually housed pigs that were infected sequentially with H1N1 and H3N2 swIAV strains. The same methods were also applied to oral fluid samples spiked with H1N1 to study the influence of conservation time and temperature on swIAV infectivity and detectability in porcine oral fluid.
Results:
All swIAV infected animals were found qRT-PCR positive in both nasal swabs and oral fluid. However, swIAV could be detected for a longer period in oral fluid than in nasal swabs. Despite the high detectability of swIAV in oral fluid, virus isolation from oral fluid collected from infected pigs was rare. These results are supported by laboratory studies showing that the PCR detectability of swIAV remains unaltered during a 24 h incubation period in oral fluid, while swIAV infectivity drops dramatically immediately upon contact with oral fluid (3 log titer reduction) and gets lost after 24 h conservation in oral fluid at ambient temperature.
Conclusions:
Our data indicate that porcine oral fluid has the potential to replace nasal swabs for molecular diagnostic purposes. The difficulty to isolate swIAV from oral fluid could pose a drawback for its use in active surveillance programs.
Oedema disease is one of the major diseases in pigs during the nursery period. It is caused by Shigatoxin 2e producing strains of Escherichia coli. In order to combat the disease, the metaphylactic use of colistin sulphate and zinc oxide is widely spread. Additionally, special feeding regimens such as the reduction of the amount of crude protein and the increase of the amount of crude fibre are applied. The goal of this study was to test the efficacy of a vaccine against Oedema disease caused by Shigatoxin 2e in a field trial on a farm with a history of Oedema disease in nursery pigs.
The study was carried out on a Dutch farm with 600 sows and a one-week farrowing rhythm and lasted for the time of one year. During this time all piglets were vaccinated with 1 ml ECOPORC SHIGA at the average age of 4 days. The parameters Overall mortality, use of antimicrobials in general, calculated as defined daily dose per animal, use of colistin sulphate and the weight gain were evaluated for all nursery pigs and compared to historical data of animals from the same period of time directly prior to the study serving as a historical control group.
The previous mortality in the nursery of 7.7% was significantly reduced to 1.3% after vaccination. The metaphylactic use of colistin sulphate during the nursery period was stopped during the study because no deaths due to Oedema disease had occurred anymore after beginning of vaccination. The defined daily dose per animal per month was significantly reduced from a mean of 1.050 in the year 2012 to a mean of 0.215 in the year 2013. The defined daily dose per animal per year was therefore relevantly reduced from 12.6 in 2012 to 2.6 in 2013.
These results show that on this farm Oedema disease can not only be controlled successfully by vaccination but also that vaccination can significantly reduce the use of antimicrobials in the nursery period.
Objectives: To validate the use of oral fluids to detect infections with porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) in three commercial swine herds. Materials and methods: Oral-fluid and serum samples were collected from one barn on each of three PRRSV-infected finishing sites. Six pens per barn (20 to 30 pigs per pen) were sampled repeatedly, beginning when the pigs entered the facilities (3 weeks of age), and then at 5, 8, 12, and 16 weeks of age. Serum samples were tested using a commercial PRRS ELISA. Both serum and oral-fluid samples were tested for PRRSV by quantitative reverse-transcriptase polymerase chain reaction (PCR), and oral fluids were tested for PCV2 by quantitative PCR. Results: Site One pigs seroconverted to PRRS at 8 to 12 weeks of age, and Site Two and Three pigs at 5 to 8 weeks of age. At all sites, individual serum samples tested PCR-negative for PRRSV in pigs 3 and 5 weeks old, while > 1 sample tested positive in pigs 8, 12, and 16 weeks old. Overall, there was 77% agreement between oral-fluid and serum pen-level results. At all sites, PCV2 was repeatedly detected in oral fluids. Implications: Oral-fluid samples may be used to monitor PRRSV and PCV2 infections in commercial production systems. PRRS virus is detectable in oral fluids for 3 to 8 weeks, and PCV2 may be detectable for > 8 weeks. Sampling at 2- to 4-week intervals is recommended for surveillance of PRRSV and PCV2.
Porcine reproductive and respiratory syndrome (PRRS) is a disease that is both highly contagious and of great economic importance in Malaysia. Therefore, reliable and improved diagnostic methods are needed to facilitate disease surveillance. This study compared PRRSV antibody responses in oral fluid versus serum samples following PRRS modified live (MLV) vaccination using commercial antibody ELISA kits (IDEXX Laboratories, Inc.). The study involved two pig farms located in Perak and Selangor, Malaysia. Both farms were vaccinated with PRRS MLV 1 month prior to sample collection. Thirty-five animals were used as subjects in each farm. These 35 animals were divided into 7 different categories: gilts, young sows, old sows, and four weaner groups. Oral fluid and serum samples were collected from these animals individually. In addition, pen oral fluid samples were collected from weaner groups. The oral fluid and serum samples were tested with IDEXX PRRS Oral Fluid Antibody Test Kit and IDEXX PRRS X3 Antibody Test Kit, respectively. The results were based on sample to positive ratio (S/P ratio of the samples). Results revealed a significant and positive correlation between serum and oral fluid samples for both farm A (p = 0.0001, r = 0.681) and farm B (p = 0.0001, r = 0.601). In general, oral fluids provided higher S/P results than serum, but the patterns of response were highly similar, especially for the sow groups. Thus, the use of oral fluids in endemic farms is effective and economical, particularly for large herds. In conclusion, the authors strongly recommend the use of oral fluids for PRRS monitoring in endemic farms.
Mycoplasma hyorhinis and M. hyosynoviae are pathogens known to cause disease in pigs post-weaning. Due to their fastidious nature, there is increased need for culture-independent diagnostic platforms to be for their detection. Therefore, this study sought to develop and optimize quantitative real-time polymerase chain reaction assays (qPCR) to rapidly detect M. hyorhinis and M. hyosynoviae using pen-based oral fluids, nasal and tonsillar fluids as proxies to evaluate samples used in swine herd surveillance. Two methods of genomic DNA extraction, automated vs. manual, were used to compare diagnostic tests performance. A wean-to-finish longitudinal study was also carried out to demonstrate the reproducibility of using pen-based oral fluids. Overall, pen-based oral fluids and tonsillar fluids were more likely to be positive for both bacteria, whereas only M. hyorhinis was detected in nasal fluids. DNA extraction protocols were shown to significantly influence test result. Mycoplasma hyosynoviae had a late initial detection compared to M. hyorhinis, but both organisms were repeatedly detected in the longitudinal study. Collectively, this study described two qPCR methods to be used for rapid and specific detection of either mycoplasma, potentiating studies to determine their prevalence, environmental load, and effectiveness of veterinary interventions for infection control.
There has been a developing interest in the use of oral fluid for the diagnosis of different pathogens such as Porcine reproductive and respiratory syndrome virus (PRRSV). PRRSV and PRRSV-specific antibodies have been shown to be present in oral fluid samples, but the correlation between diagnostic results in oral fluid and serum samples has been insufficiently addressed. Studies investigating this correlation focused on boars older than 6 months and type 2 strains, but it is known that the outcome of a PRRSV infection is age and strain dependent. To address this gap, the current study reports on the detection of PRRSV and PRRSV-specific antibodies in serum and oral fluid samples collected over a 6-week period after an experimental infection of 8-week-old individually housed pigs with Lelystad virus, the type 1 prototype strain. Quantitative reverse transcription polymerase chain reaction analysis showed that significantly more serum samples were PRRSV RNA-positive than oral fluid until 5 days postinfection (dpi). Between 7 and 21 dpi, PRRSV RNA detection was similar in both samples but higher detection rates in oral fluid were found from 28 dpi. Compared with existing literature, this highlights that detection rates at particular time points postinfection might vary in function of strain virulence and animal age and provides useful information for the interpretation of pen-based oral fluid results. An excellent agreement between the oral fluid and serum enzyme-linked immunosorbent assay results was observed at every time point, further supporting the usefulness of oral fluid as a diagnostic sample for antibody detection.
© 2014 The Author(s).
Diet has been implicated as a major factor impacting clinical disease expression of swine dysentery and Brachyspira hyodysenteriae colonization. However, the impact of diet on novel pathogenic strongly beta-hemolytic Brachyspira spp. including "B. hampsonii" has yet to be investigated. In recent years, distillers dried grains with solubles (DDGS), a source of insoluble dietary fiber, has been increasingly included in diets of swine. A randomized complete block experiment was used to examine the effect of increased dietary fiber through the feeding of DDGS on the incidence of Brachyspira-associated colitis in pigs. One hundred 4-week-old pigs were divided into five groups based upon inocula (negative control, Brachyspira intermedia, Brachyspira pilosicoli, B. hyodysenteriae or "B. hampsonii") and fed one of two diets containing no (diet 1) or 30% (diet 2) DDGS. The average days to first positive culture and days post inoculation to the onset of clinical dysentery in the B. hyodysenteriae groups was significantly shorter for diet 2 when compared to diet 1 (P = 0.04 and P = 0.0009, respectively). A similar difference in the average days to first positive culture and days post inoculation to the onset of clinical dysentery was found when comparing the "B. hampsonii" groups. In this study, pigs receiving 30% DDGS shed on average one day prior to and developed swine dysentery nearly twice as fast as pigs receiving 0% DDGS. Accordingly, these data suggest a reduction in insoluble fiber through reducing or eliminating DDGS in swine rations should be considered an integral part of any effective disease elimination strategy for swine dysentery.
Mycoplasma hyorhinis has emerged as an important cause of systemic disease in nursery pigs. However, this bacterium can also be found in the upper respiratory tract of healthy swine. The current study describes the development of a quantitative polymerase chain reaction assay for the detection of M. hyorhinis and the evaluation of the assay in both disease diagnosis and disease surveillance using a large number of field samples. The analytical sensitivity was estimated to be 12 genome equivalents/μl. The assay was highly specific, detecting all 25 M. hyorhinis isolates tested and none of the 19 nontarget species tested. Assay repeatability was evaluated by testing different matrices spiked with known amounts of M. hyorhinis. Overall, assessment of the repeatability of the assay showed suitable precision within and between runs for all matrices. The coefficient of variation ranged from 10% to 24%. Mycoplasma hyorhinis DNA was detected in 48% of samples (pericardium, pleura, joints, nasal cavity, and lungs) from pigs with systemic disease. Mycoplasma hyorhinis was detected in nasal (92%) and oropharyngeal swabs (66%), as well as in oral fluids (100%). Potential uses of this tool involve the characterization of the prevalence of this pathogen in swine herds as well as bacterial quantification to evaluate intervention efficacy.
African swine fever virus (ASFV) is a highly virulent swine pathogen that has spread across Eastern Europe since 2007 and for which there is no effective vaccine or treatment available. The dynamics of shedding and excretion is not well known for this currently circulating ASFV strain. Therefore, susceptible pigs were exposed to pigs intramuscularly infected with the Georgia 2007/1 ASFV strain to measure those dynamics through within- and between-pen transmission scenarios. Blood, oral, nasal and rectal fluid samples were tested for the presence of ASFV by virus titration (VT) and quantitative real-time polymerase chain reaction (qPCR). Serum was tested for the presence of ASFV-specific antibodies. Both intramuscular inoculation and contact transmission resulted in development of acute disease in all pigs although the experiments indicated that the pathogenesis of the disease might be different, depending on the route of infection. Infectious ASFV was first isolated in blood among the inoculated pigs by day 3, and then chronologically among the direct and indirect contact pigs, by day 10 and 13, respectively. Close to the onset of clinical signs, higher ASFV titres were found in blood compared with nasal and rectal fluid samples among all pigs. No infectious ASFV was isolated in oral fluid samples although ASFV genome copies were detected. Only one animal developed antibodies starting after 12 days post-inoculation. The results provide quantitative data on shedding and excretion of the Georgia 2007/1 ASFV strain among domestic pigs and suggest a limited potential of this isolate to cause persistent infection.
The objectives of the present study were to investigate the anatomic localization of porcine reproductive and respiratory syndrome virus (PRRSV), and to determine whether oral fluid could be used for the detection of PRRSV in naturally infected pigs in a breeding herd. Two sows that had aborted, seven two-month-old grower pigs and seventy six-month-old gilts were used in this study. PRRSV in sera and oral fluid were assayed by nested reverse transcription polymerase chain reaction (nRT-PCR), tissues sample were tested by nRT-PCR, immunohistochemistry (IHC) and in situ hybridization (ISH). In aborted sows, PRRSV was identified in the oral fluid and tonsils. PRRSV was detected in oral fluid, tonsils, salivary glands, oral mucosa and lungs of all seven grower pigs. However, viremia was detected in only two grower pigs. Double staining revealed that PRRSV was distributed in macrophages within and adjacent to the tonsillar crypt epithelium. In gilts, North American (NA) type PRRSV field strain was detected at 3 to 8 weeks after introduction onto the farm. These results confirm previous findings that in sows, PRRSV primarily replicates in tonsils, and is then shed into oral fluid. Oral fluid sampling may therefore be effective for PRRSV surveillance in breeding herds.
Background
The object of this study was to describe and contrast the kinetics of the humoral response in serum and oral fluid specimens during acute porcine reproductive and respiratory syndrome virus (PRRSV) infection. The study involved three trials of 24 boars each. Boars were intramuscularly inoculated with a commercial modified live virus (MLV) vaccine (Trial 1), a Type 1 PRRSV field isolated (Trial 2), or a Type 2 PRRSV field isolate (Trial 3). Oral fluid samples were collected from individual boars on day post inoculation (DPI) -7 and 0 to 21. Serum samples were collected from all boars on DPI −7, 0, 7, 14, 21 and from 4 randomly selected boars on DPI 3, 5, 10, and 17. Thereafter, serum and oral fluid were assayed for PRRSV antibody using antibody isotype-specific ELISAs (IgM, IgA, IgG) adapted to serum or oral fluid.
Results
Statistically significant differences in viral replication and antibody responses were observed among the three trials in both serum and oral fluid specimens. PRRSV serum IgM, IgA, and IgG were first detected in samples collected on DPI 7, 10, and 10, respectively. Oral fluid IgM, IgA, and IgG were detected in samples collected between DPI 3 to 10, 7 to 10, and 8 to 14, respectively.
Conclusions
This study enhanced our knowledge of the PRRSV humoral immune response and provided a broader foundation for the development and application of oral fluid antibody-based diagnostics.
Pen-based oral fluid sampling has proven to be an efficient method for surveillance of infectious diseases in swine populations. To better interpret diagnostic results, the performance of oral fluid assays (antibody- and nucleic acid-based) must be established for pen-based oral fluid samples. Therefore, the objective of the current study was to determine the probability of detecting Porcine reproductive and respiratory syndrome virus (PRRSV) infection in pen-based oral fluid samples from pens of known PRRSV prevalence. In 1 commercial swine barn, 25 pens were assigned to 1 of 5 levels of PRRSV prevalence (0%, 4%, 12%, 20%, or 36%) by placing a fixed number (0, 1, 3, 5, or 9) of PRRSV-positive pigs (14 days post PRRSV modified live virus vaccination) in each pen. Prior to placement of the vaccinated pigs, 1 oral fluid sample was collected from each pen. Thereafter, 5 oral fluid samples were collected from each pen, for a total of 150 samples. To confirm individual pig PRRSV status, serum samples from the PRRSV-negative pigs (n = 535) and the PRRSV vaccinated pigs (n = 90) were tested for PRRSV antibodies and PRRSV RNA. The 150 pen-based oral fluid samples were assayed for PRRSV antibody and PRRSV RNA at 6 laboratories. Among the 100 samples from pens containing ≥1 positive pig (≥4% prevalence) and tested at the 6 laboratories, the mean positivity was 62% for PRRSV RNA and 61% for PRRSV antibody. These results support the use of pen-based oral fluid sampling for PRRSV surveillance in commercial pig populations.
Calf diarrhea (scours) is a primary cause of illness and death in young calves. Significant economic losses associated with this disease include morbidity, mortality, and direct cost of treatment. Multiple pathogens are responsible for infectious diarrhea, including, but not limited to, Bovine coronavirus (BCV), bovine Rotavirus A (BRV), and Cryptosporidium spp. Identification and isolation of carrier calves are essential for disease management. Texas Veterinary Medical Diagnostic Laboratory current methods for calf diarrhea pathogen identification include electron microscopy (EM) for BCV and BRV and a direct fluorescent antibody test (DFAT) for organism detection of Cryptosporidium spp. A workflow was developed consisting of an optimized fecal nucleic acid purification and multiplex reverse transcription quantitative polymerase chain reaction (RT-qPCR) for single tube concurrent detection of BCV, BRV, and Cryptosporidium spp., and an internal control to monitor nucleic acid purification efficacy and PCR reagent functionality. In "spike-in" experiments using serial dilutions of each pathogen, the analytical sensitivity was determined to be <10 TCID(50)/ml for BCV and BRV, and <20 oocysts for Cryptosporidium spp. Analytical specificity was confirmed using Canine and Feline coronavirus, Giardia spp., and noninfected bovine purified nucleic acid. Diagnostic sensitivity was ≥98% for all pathogens when compared with respective traditional methods. The results demonstrate that the newly developed assay can purify and subsequently detect BCV, BRV, and Cryptosporidium spp. concurrently in a single PCR, enabling simplified and streamlined calf diarrhea pathogen identification.
The purpose of the present study was to evaluate the diagnostic performance of a commercial serum antibody enzyme-linked immunosorbent assay (ELISA) modified to detect anti-Porcine reproductive and respiratory syndrome virus (PRRSV) antibodies in pen-based oral fluid specimens. Experimental and field oral fluid samples of defined status in reference to exposure of swine with PRRSV were used to derive the kinetics of detectable concentrations of antibody against PRRSV. Immunoglobulin (Ig)M and IgA were readily detected in oral fluid specimens from populations in which PRRSV infection was synchronized among all individuals but not in samples collected in commecial herds. In contrast, IgG was readily detected at diagnostically useful levels in both experimental and field samples for up to 126 days. Estimates of the IgG oral fluid ELISA performance were based on results from testing positive oral fluid samples (n = 492) from experimentally inoculated pigs (n = 251) and field samples (n = 241) and negative oral fluid samples (n = 367) from experimentally inoculated pigs (n = 84) and field samples (n = 283). Receiver operating characteristic analysis estimated the diagnostic sensitivity and specificity of the assay as 94.7% (95% confidence interval [CI]: 92.4, 96.5) and 100% (95% CI: 99.0, 100.0), respectively, at a sample-to-positive ratio cutoff of ≥0.40. The results of the study suggest that the IgG oral fluid ELISA can provide efficient, cost-effective PRRSV monitoring in commercial herds and PRRSV surveillance in elimination programs.
For effective disease surveillance, rapid and sensitive assays are needed to detect antibodies developed in response to porcine reproductive and respiratory syndrome virus (PRRSV) infection. In this study, we developed a multiplexed fluorescent microsphere immunoassay (FMIA) for detection of PRRSV-specific antibodies in oral fluid and serum samples. Recombinant nucleocapsid protein (N) and nonstructural protein 7 (nsp7) from both PRRSV genotypes (type I and type II) were used as antigens and covalently coupled to Luminex fluorescent microspheres. Based on an evaluation of 488 oral fluid samples with known serostatus, the oral fluid-based FMIAs achieved >92% sensitivity and 91% specificity. For serum samples (n = 1,639), the FMIAs reached >98% sensitivity and 95% specificity. The assay was further employed to investigate the kinetics of the antibody response in infected pigs. In oral fluid, the N protein was more sensitive for the detection of early infection (7 and 14 days postinfection), but nsp7 detected a higher level and longer duration of antibody response (28 days postinfection). In serum, the antibodies specific to nsp7 and N proteins were detected as early as 7 days postinfection, and the responses lasted more than 202 days. This study provides a framework from which a more robust assay could be developed to profile the immune response to multiple PRRSV antigens in a single test. The development of oral fluid-based diagnostic tests will change the way we survey diseases in swine herds and improve our ability to cheaply and efficiently track PRRSV infections in both populations and individual animals.
Virus nucleic acids and antibody response to pathogens can be measured using swine oral fluids (OFs). Detection of foot-and-mouth disease virus (FMDV) genome in swine OFs has previously been demonstrated. Virus isolation and viral antigen detection are additional confirmatory assays for diagnosing FMDV, but these methods have not been evaluated using swine OF. The objectives of this study were to further validate the molecular detection of FMDV in oral fluids, evaluate antigen detection and FMDV isolation from swine OFs, and develop an assay for isotypic anti-FMDV antibody detection in OFs. Ribonucleic acid (RNA) from FMDV was detected in OFs from experimentally infected pigs by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) from 1 day post-infection (dpi) to 21 dpi. Foot-and-mouth disease virus (FMDV) was isolated from OFs at 1 to 5 dpi. Additionally, FMDV antigens were detected in OFs from 1 to 6 dpi using a lateral flow immunochromatographic strip test (LFIST), which is a rapid pen-side test, and from 2 to 3 dpi using a double-antibody sandwich enzyme-linked immunosorbent assay (DAS ELISA). Furthermore, FMDV-specific immunoglobulin A (IgA) was detected in OFs using an isotype-specific indirect ELISA starting at dpi 14. These results further demonstrated the potential use of oral fluids for detecting FMDV genome, live virus, and viral antigens, as well as for quantifying mucosal IgA antibody response.
The feasibility of using individual and pen-based oral fluid samples to detect PRRSV antibodies in growing-finishing pigs and group-housed sows was investigated. The diagnostic performances of a commercial oral fluid ELISA (OF-ELISA) and a serum ELISA (SER-ELISA) performed on individual or pooled samples from 5 or 10 pigs and sows was evaluated. The performance of the OF-ELISA was also assessed for pen-based oral fluids. Eight hundred and thirty-four pigs and 1,598 sows from 42 PRRSV-infected and 3 PRRSV-negative herds were oral fluid sampled and bled. PRRSV antibodies were detected by an OF-ELISA performed at individual, pool (5 or 10 samples) and pen levels. Serum samples were tested by a SER-ELISA at individual and pool levels. The sensitivity and specificity of ELISAs for individual samples were assessed by Bayesian analysis. The relative diagnostic performance for the pools was calculated by taking individual samples as the gold standard. SER-ELISA and individual OF-ELISA results were used as references for estimating OF-ELISA performance for pen-based samples. Individual oral fluid collection was feasible in all kinds of pigs, whereas pen-based samples were unsuccessful in 40% of the group-housed sow pens. High levels of sensitivity comparable to those of the SER-ELISA were found for the OF-ELISA when performed on individual, 5-sample pool or pen-based samples from pigs or sows. The OF-ELISA lacked specificity for individual samples from sows. Pooling 5 individual oral fluid samples or using pen-based samples increased test specificity.
The detection of porcine reproductive and respiratory syndrome virus (PRRSV) in oral fluids (OF) by quantitative real-time polymerase chain reaction (qRT-PCR) is gaining increasing popularity. However, the different steps leading to a result have not been extensively evaluated. The aim of the present study was to examine the effect on the performance of qRT-PCR with different sampling materials, conditions of storage of the OF, the need for centrifuging OF, as well as to compare RNA extraction methods and PCR mixes. For the assays, pen-based oral fluids were used, which were pooled and spiked in a serial dilution (up to genotype 10⁰ TCID50/mL) of type 1 PRRSV isolate 3267. Centrifugation at 15,000g for 15 min resulted in an increase in sensitivity (1-2 PCR cycles) that was significant (p < 0.05) at the lowest dilution tested. The TRIzol and MagMAX RNA extraction methods gave the maximum sensitivity, lowest threshold cycle (Ct), at equivalent virus concentrations. The AgPath-ID One-Step RT-PCR Kit PCR mix reagents were more sensitive for the detection of PRRSV using a purified plasmid as standard, but LSI VetMAX PRRSV EU/NA PRRSV reagents resulted in a slightly better sensitivity with OF (p < 0.05). The present results may be useful to standardize protocols for optimizing detection of type 1 PRRSV in OF by qRT-PCR.
Next-generation sequencing (NGS) technologies have increasingly played crucial roles in biological and medical research, but are not yet in routine use in veterinary diagnostic laboratories. We developed and applied a procedure for high-throughput RNA sequencing of Porcine reproductive and respiratory syndrome virus (PRRSV) from cell culture–derived isolates and clinical specimens. Ten PRRSV isolates with known sequence information, 2 mixtures each with 2 different PRRSV isolates, and 51 clinical specimens (19 sera, 16 lungs, and 16 oral fluids) with various PCR threshold cycle (Ct) values were subjected to nucleic acid extraction, cDNA library preparation (24-plexed), and sequencing. Whole genome sequences were obtained from 10 reference isolates with expected sequences and from sera with a PRRSV real-time reverse transcription PCR Ct ≤ 23.6, lung tissues with Ct ≤ 21, and oral fluids with Ct ≤ 20.6. For mixtures with PRRSV-1 and -2 isolates (57.8% nucleotide identity), NGS was able to distinguish them as well as obtain their respective genome sequences. For mixtures with 2 PRRSV-2 isolates (92.4% nucleotide identity), sequence reads with nucleotide ambiguity at numerous sites were observed, indicating mixed infection; however, individual virus sequences could only be separated when 1 isolate identity and sequence in the mixture is known. The NGS approach described herein offers the prospect of high-throughput sequencing and could be adapted to routine workflows in veterinary diagnostic laboratories, although further improvement of sequencing outcomes from clinical specimens with higher Ct values remains to be investigated.
Recently oral fluid has become a novel sample type for pathogen nucleic acid and antibody detection, as it is easy to obtain with non-invasive procedures. The objective of the study was to analyze porcine reproductive and respiratory syndrome virus (PRRSV) and influenza A virus (IAV) circulation in growing pigs from three Polish production farms, using Real Time PCR and ELISA testing of oral fluid and serum. Oral fluids were collected every 2 weeks, in the same 3–4 pens of pigs aged between 5 and 17 weeks. Additionally, blood samples were collected every 4 weeks from 4 pigs corresponding to the same pens as oral fluid and tested for the presence of PRRSV nucleic acid (pooled by 4) and antibodies. In farm A no PRRSV circulation was detected and only maternal anti-bodies were present. In farm B and farm C antibodies to PRRSV in serum and oral fluid were detected in most samples. In farm B PRRSV Type 1 was detected in 80.9% of oral fluid samples and in 58.3% of serum pools, and in farm C in 92.8% of oral fluid samples and 75% serum pools. Striking differences were observed between different pens in PRRSV detection patterns. In farms B and C ORF5 sequence analysis showed the presence of wild type strains which were about 84–85% identical to the modified live vaccine used. In all three farms two waves of IAV shedding with oral fluid were detected, in weaners and fatteners.
The use of swine oral fluid (OF) for the detection of nucleic acids and antibodies is gaining significant popularity. Assays have been developed for this purpose for endemic and foreign animal diseases of swine. Here, we report the use of OF for the detection of virus and antibodies in pigs experimentally infected with swine vesicular disease virus (SVDV), a virus that causes a disease clinically indistinguishable from the economically devastating foot-and-mouth disease. Viral genome was detected in OF by real-time reverse transcription polymerase chain reaction (RRT-PCR) from 1 day post-infection (DPI) to 21 DPI. Virus isolation from OF was also successful at 1–5 DPI. An adapted competitive ELISA based on the monoclonal antibodies 5B7 detected antibodies to SVDV in OF starting at DPI 6. Additionally, using isotype-specific indirect ELISAs, SVDV-specific IgM and IgA were evaluated in OF. IgM response started at DPI 6, peaking at DPI 7 or 14 and declining sharply at DPI 21, while IgA response started at DPI 7, peaked at DPI 14 and remained high until the end of the experiment. These results confirm the potential use of OF for SVD surveillance using both established and partially validated assays in this study.
In early 1991, the Dutch pig-industry was struck by the so-called mystery swine disease. Large-scale laboratory investigations were undertaken to search for the etiological agent. We focused on isolating viruses and mycoplasmas, and we tested paired sera of affected sows for antibodies against ten known pig viruses. The mycoplasmas M. hyosynoviae, M. hyopneumoniae, and Acholeplasma laidlawii, and the viruses encephalomyocarditis virus and porcine enterovirus types 2 and 7 were isolated from individual pigs. An unknown agent, however, was isolated from 16 of 20 piglets and from 41 of 63 sows. This agent was characterised as a virus and designated Lelystad virus. No relationship between this virus and other viruses has yet been established. Of 165 sows reportedly afflicted by the disease, 123 (75 per cent) seroconverted to Lelystad virus, whereas less than 10 per cent seroconverted to any of the other virus isolates or to the known viral pathogens. Antibodies directed against Lelystad virus were also found in pigs with mystery swine disease in England, Germany, and in the United States. We conclude that infection with Lelystad virus is the likely cause of mystery swine disease.
Objectives: To evaluate the feasibility and utility of oral-fluids collection for surveillance of porcine viruses in the Mekong Delta, Vietnam, and to establish baseline serological and virological prevalence estimates for porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2), and influenza A virus (IAV) among smallholder farms. Materials and methods: Paired serum and oral-fluids samples from 68 farms (sows, boars, weaners, and growers) were tested during 2011 by reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay for PRRSV, PCV2, and IAV. Results: Low numbers of PRRSV-positive and IAV-positive pigs were detected (1.6% PRRSV viremic, two of 124; 0.8% JAY in oral fluids, one of 124). However, PCV2 detection rates were high in both serum and oral fluids (54.8% and 61.3%, respectively). Overall proportions of pigs seropositive for IAV and PRRSV were 37.9% and 33.9%, respectively. Proportions of pigs seropositive for PRRSV were 48.6% (17 of 35) and 12.1% (four of 33) on vaccinated and unvaccinated farms, respectively. Oral fluids and serum samples yielded comparable prevalence estimates for molecular detection of PCV2, and detected one sample PCR-positive for hemagglutinin of influenza A/H1N1/pdm09. There was no evidence of PRRSV shedding in oral fluids.
The probability of detecting influenza A virus (IAV) in oral fluid (OF) specimens was calculated for each of 13 assays based on real-time reverse-transcription polymerase chain reaction (rRT-PCR) and 7 assays based on virus isolation (VI). The OF specimens were inoculated with H1N1 or H3N2 IAV and serially diluted 10-fold (10-1 to 10-8). Eight participating laboratories received 180 randomized OF samples (10 replicates × 8 dilutions × 2 IAV subtypes plus 20 IAV-negative samples) and performed the rRT-PCR and VI procedure(s) of their choice. Analysis of the results with a mixed-effect logistic-regression model identified dilution and assay as variables significant (P, 0.0001) for IAV detection in OF by rRT-PCR or VI. Virus subtype was not significant for IAV detection by either rRT-PCR (P = 0.457) or VI (P = 0.101). For rRT-PCR the cycle threshold (Ct) values increased consistently with dilution but varied widely. Therefore, it was not possible to predict VI success on the basis of Ct values. The success of VI was inversely related to the dilution of the sample; the assay was generally unsuccessful at lower virus concentrations. Successful swine health monitoring and disease surveillance require assays with consistent performance, but significant differences in reproducibility were observed among the assays evaluated. © 2015, Brazilian Statistical Association. All rights reserved.
The use of cotton ropes has been recently proposed to collect oral fluids from pigs as a method to detect and monitor viral infections in swine populations. However, its use for detection and monitoring of swine bacterial pathogens by polymerase chain reaction (PCR) has not been assessed. In this study, oral-fluid testing for diagnosis of Actinobacillus pleuropneumoniae was evaluated over time, utilizing samples from experimentally infected pigs. Eighty pigs were randomly assigned to experimental groups infected with A pleuropneumoniae serovars 1, 3, 5, 7,10, 12, or 15 and a non-inoculated control group. Oral fluids and blood samples were collected prior to infection, 1 day post infection, and weekly thereafter for 7 consecutive weeks. Oral fluids were tested for A pleuropneumoniae, Haemophilus parasuis, and Streptococcus suis by specific PCR tests offered by the Minnesota Veterinary Diagnostic Laboratory. Actinobacillus pleuropneumoniae was detected on days 1 and 7 post infection, whereas H parasuis and S suis, normal colonizers of the swine respiratory tract, were detected at all time points. These results indicate that oral-fluid testing has the potential to be a screening tool for detection of swine bacterial pathogens. Field studies are indicated to explore this potential further.
In North American swine there are numerous antigenically distinct H1 influenza A virus (IAV) variants currently circulating, making vaccine development difficult due to the inability to formulate a vaccine that provides broad cross-protection. Experimentally, live-attenuated influenza virus (LAIV) vaccines demonstrate increased cross-protection compared to inactivated vaccines. However, there is no standardized assay to predict cross-protection following LAIV vaccination. Hemagglutination-inhibiting (HI) antibody in serum is the gold standard correlate of protection following IAV vaccination. LAIV vaccination does not induce a robust serum HI antibody titer; however, a local mucosal antibody response is elicited. Thus, a live-animal sample source that could be used to evaluate LAIV immunogenicity and cross-protection is needed. Here, we evaluated the use of oral fluids (OF) and nasal wash (NW) collected after IAV inoculation as a live-animal sample source in an ELISA to predict cross-protection in comparison to traditional serology. Both live-virus exposure and LAIV vaccination provided heterologous protection, though protection was greatest against more phylogenetically related viruses. IAV-specific IgA was detected in NW and OF samples and was cross-reactive against representative IAV from each H1 cluster. Endpoint titers of cross-reactive IgA in OF from pigs exposed to live-virus was associated with heterologous protection. While LAIV vaccination provided significant protection, LAIV immunogenicity was reduced compared to live-virus exposure. These data suggest that OF from pigs inoculated with wild-type IAV, with surface genes that match the LAIV seed strain, could be used in an ELISA to assess cross-protection and antigenic relatedness of circulating and emerging IAV in swine.
Copyright © 2015, American Society for Microbiology. All Rights Reserved.
Oral fluid samples collected from litters of piglets (n=600) one day prior to weaning were evaluated as a method to surveil for porcine reproductive and respiratory syndrome virus (PRRSV) infections in four sow herds of approximately 12,500 sow each. Serum samples from the litters' dam (n=600) were included for comparison. All four herds were endemically infected with PRRSV and all sows had been vaccinated ≥2 times with PRRSV modified-live virus vaccines. After all specimens had been collected, samples were randomized and assayed by PRRSV real-time reverse transcription polymerase chain reaction (RT-qPCR) and four PRRSV antibody ELISA assays (IgM, IgA, IgG, and Commercial Kit). All sow serum samples were negative by PRRSV RT-qPCR, but 9 of 600 oral fluid samples tested positive at two laboratories. Open reading frame 5 (ORF5) sequencing of 2 of the 9 positive oral fluid samples identified wild-type viruses as the source of the infection. A comparison of antibody responses in RT-qPCR positive vs. negative oral fluid samples showed significantly higher IgG S/P ratios in RT-qPCR-positive oral fluid samples (mean S/P 3.46 vs. 2.36; p=0.02). Likewise, sow serum samples from RT-qPCR-positive litter oral fluid samples showed significantly higher serum IgG (mean S/P 1.73 vs. 0.98; p<0.001) and Commercial Kit (mean S/P 1.97 vs. 0.98; p<0.001) S/P ratios. Overall, the study showed that pre-weaning litter oral fluid samples could provide an efficient and sensitive approach to surveil for PRRSV in infected, vaccinated, or presumed-negative pig breeding herds.
Indirect influenza A virus (IAV) nucleoprotein (NP) antibody ELISAs were used to compare the kinetics of the NP IgM, IgA, and IgG responses in serum and pen-based oral fluid samples collected from 82 pigs followed for 42 days post inoculation (DPI). Treatment categories included vaccination (0, 1) and inoculation (0, 1) with contemporary H1N1 or H3N2 isolates. Antibody ontogeny was markedly affected by vaccination status, but no significant differences were detected between H1N1 and H3N2 inoculated groups of the same vaccination status (0, 1) in IgM, IgA, or IgG responses. Therefore, these data were combined in subsequent analyses. The correlation between serum and oral fluid responses was evaluated using the pen-based oral fluid sample-to-positive (S/P) ratios versus the mean serum S/P ratios of pigs within the pen. IgM responses in serum and oral fluid were highly correlated in unvaccinated groups (r=0.810), as were serum and oral fluid IgG responses in both unvaccinated (r=0.839) and vaccinated (r=0.856) groups. In contrast, IgM responses were not correlated in vaccinated groups and the correlation between serum and oral fluid IgA was weak (r∼0.3), regardless of vaccination status. In general, vaccinated animals exhibited a suppressed IgM response and accelerated IgG response. The results from this study demonstrated that NP-specific IgM, IgA, and IgG antibody were detectable in serum and oral fluid and their ontogeny was influenced by vaccination status, the time course of the infection, and specimen type.
During the 10 days commencing April 29, 2013, the Iowa State University Veterinary Diagnostic Laboratory received the first 4 of many submissions from swine farms experiencing explosive epidemics of diarrhea and vomiting affecting all ages, with 90-95% mortality in suckling pigs. Histology revealed severe atrophy of villi in all segments of the small intestines with occasional villus-epithelial syncytial cells, but testing for rotaviruses and Transmissible gastroenteritis virus (Alphacoronavirus 1) were negative. Negative-staining electron microscopy of feces revealed coronavirus-like particles and a pan-coronavirus polymerase chain reaction (PCR) designed to amplify a conserved region of the polymerase gene for all members in the family Coronaviridae produced expected 251-bp amplicons. Subsequent sequencing and analysis revealed 99.6-100% identity among the PCR amplicons from the 4 farms and 97-99% identity to the corresponding portion of the polymerase gene of Porcine epidemic diarrhea virus (PEDV) strains, with the highest identity (99%) to strains from China in 2012. Findings were corroborated at National Veterinary Services Laboratories using 2 nested S-gene and 1 nested N-gene PCR tests where the sequenced amplicons also had the highest identity with 2012 China strains. Whole genome sequence for the virus from 2 farms in 2 different states using next-generation sequencing technique was compared to PEDV sequences available in GenBank. The 2013 U.S. PEDV had 96.6-99.5% identity with all known PEDV strains and the highest identity (>99.0%) to some of the 2011-2012 Chinese strains. The nearly simultaneous outbreaks of disease, and high degree of homology (99.6-100%) between the PEDV strains from the 4 unrelated farms, suggests a common source of virus.
Porcine reproductive and respiratory syndrome virus (PRRSV)-contaminated semen from boars is a route of transmission to females, and early detection of PRRSV infection in boars is a key component in sow farm biosecurity. The purpose of this study was to determine the optimum diagnostic specimen(s) for the detection of acute PRRSV infection in boars. Individually housed boars (n = 15) were trained for semen and oral fluid collection and then vaccinated with a commercial PRRSV modified live virus vaccine. Starting on the day of vaccination and for 14 days thereafter, oral fluid specimens were collected daily from all boars. The 15 boars were subdivided into three groups of 5, and serum, blood swabs and 'frothy saliva' were collected at the time of semen collection on a 3-day rotation. Frothy saliva, derived from the submandibular salivary gland, is produced by aroused boars. Semen was centrifuged, and semen supernatant and cell fractions were tested separately. All samples were randomly ordered and then tested by PRRSV real-time quantitative reverse-transcription polymerase chain reaction assay (rRT-PCR) and PRRSV antibody ELISA. In this study, a comparison of serum, blood swab, and oral fluid rRT-PCR results found no statistically significant differences in the onset of detection or proportion of positives, but serum was numerically superior to oral fluids for early detection. Serum and oral fluid provided identical rRT-PCR results at ≥5 day post-vaccination. Likewise, the onset of detection of PRRSV antibody in serum, oral fluid and frothy saliva was statistically equivalent, with serum results again showing a numerical advantage. These results showed that the highest assurance of providing PRRSV-negative semen to sow farms should be based on rRT-PCR testing of serum collected at the time of semen collection. This approach can be augmented with oral fluid sampling from a random selection of uncollected boars to provide for statistically valid surveillance of the boar stud.
The nature of the current epidemiological revolution in veterinary medicine is considered in terms of the previous evolution of tactics for livestock disease management, and future prospects for epidemiological surveillance as the ‘core’ activity for public and private practice of preventive veterinary medicine.
Influenza A viruses are common causes of respiratory disease in pigs and can be transmitted among multiple host species, including humans. The current lack of published information on infection dynamics of influenza viruses within swine herds hinders the ability to make informed animal health, biosecurity and surveillance programme decisions. The objectives of this serial cross-sectional study were to describe the infection dynamics of influenza virus in a two-site swine system by estimating the prevalence of influenza virus in animal subpopulations at the swine breeding herd and describing the temporal pattern of infection in a selected cohort of growing pigs weaned from the breeding herd. Nasal swab and blood samples were collected at approximately 30-day intervals from the swine breeding herd (Site 1) known to be infected with pandemic 2009 H1N1 influenza virus. Sows, gilts and neonatal pigs were sampled at each sampling event, and samples were tested for influenza virus genome using matrix gene RRT-PCR. Influenza virus was detected in neonatal pigs, but was not detected in sow or gilt populations via RRT-PCR. A virus genetically similar to that detected in the neonatal pig population at Site 1 was also detected at the wean-to-finish site (Site 2), presumably following transportation of infected weaned pigs. Longitudinal sampling of nasal swabs and oral fluids revealed that influenza virus persisted in the growing pigs at Site 2 for at least 69 days. The occurrence of influenza virus in neonatal pigs, but not breeding females, at Site 1 emphasizes the potential for virus maintenance in this dynamic subpopulation, the importance of including this subpopulation in surveillance programmes and the potential transport of influenza virus between sites via the movement of weaned pigs.
In commercial swine populations, influenza is an important component of the porcine respiratory disease complex (PRDC) and a pathogen with major economic impact. Previously, a commercial blocking ELISA (FlockChek(™) Avian Influenza Virus MultiS-Screen(®) Antibody Test Kit, IDEXX Laboratories, Inc., Westbrook, ME, USA) designed to detect influenza A nucleoprotein (NP) antibodies in avian serum was shown to accurately detect NP antibodies in swine serum. The purpose of this study was to determine whether this assay could detect NP antibodies in swine oral fluid samples. Initially, the procedure for performing the NP-blocking ELISA on oral fluid was modified from the serum testing protocol by changing sample dilution, sample volume, incubation time and incubation temperature. The detection of NP antibody was then evaluated using pen-based oral fluid samples (n = 182) from pigs inoculated with either influenza A virus subtype H1N1 or H3N2 under experimental conditions and followed for 42 days post inoculation (DPI). NP antibodies in oral fluid were detected from DPI 7 to 42 in all inoculated groups, that is, the mean sample-to-negative (S/N) ratio of influenza-inoculated pigs was significantly different (P < 0.0001) from uninoculated controls (unvaccinated or vaccinated-uninoculated groups) through this period. Oral fluid versus serum S/N ratios from the same pen showed a correlation of 0.796 (Pearson's correlation coefficient, P < 0.0001). The results showed that oral fluid samples from influenza virus-infected pigs contained detectable levels of NP antibodies for ≥42 DPI. Future research will be required to determine whether this approach could be used to monitor the circulation of influenza virus in commercial pig populations.
A recent telephone survey of 735 Dutch farmers with group housing of sows in early pregnancy suggested a wide variation in reproductive success, irrespective of husbandry system. The reason for these differences between farms is not known, but of great importance to the pig industry which is moving worldwide from individual to group housing systems, mainly for animal welfare reasons. Therefore, the aim of this review is to list the most likely success and risk factors for group housing of sows in early pregnancy, in relation to reproduction (such as pregnancy rate) and animal welfare (such as aggression and health). The review first considers a limited number of group housing comparisons and finds that the results of the few studies performed are not very conclusive, neither on fertility nor on leg problems, longevity and welfare of sows. As a consequence, it is hard to draw any significant practical conclusions, and the review proceeds to look at studies in which single factors were addressed. For the effects on fertility it is concluded that especially factors causing chronic stress (e.g. due to unfavourable social, management or climatic conditions) and a low feed intake may impact reproductive performance. The vulnerable period lies in weeks 2 and 3 of pregnancy. On leg problems and longevity an important factor seems to be the quality of the floor, regardless of other aspects of the housing system. The use of straw seems to be advantageous. Finally, on aggression it is argued that this will never be eliminated from systems in which sows are housed as a group. However, it can be properly managed and key factors in this are a gradual familiarisation of unfamiliar animals, sufficient space and pen structure during initial mixing, minimising opportunities for dominant sows to steal food from subordinates, the provision of a good quality floor and the use of straw bedding. The review concludes with a series of practical recommendations to improve welfare and reproduction in group housed sows.
A real-time quantitative PCR (qPCR) for detection of the apxIVA gene of Actinobacillus pleuropneumoniae was validated using pure cultures of A. pleuropneumoniae and tonsillar and nasal swabs from experimentally inoculated Caesarean-derived/colostrum-deprived piglets and naturally infected conventional pigs. The analytical sensitivity was 5colony forming units/reaction. In comparison with selective bacterial examination using tonsillar samples from inoculated animals, the diagnostic sensitivity of the qPCR was 0.98 and the diagnostic specificity was 1.0. The qPCR showed consistent results in repeatedly sampled conventional pigs. Tonsillar brush samples and apxIVA qPCR analysis may be useful for further epidemiological studies and monitoring for A. pleuropneumoniae.
The effective use of pooled oral fluid (OF) in disease surveillance requires that samples are representative of the group. The aim of this study was to develop a 'rope presentation' protocol to maximise the number of different pigs sampled from a pen of animals. Eight pens of grower pigs in 'fully slatted' accommodation (FS) and 'straw-kennels' (SK) were presented with a balanced sequence of 1-4 ropes. Ropes were presented for 60 min, and the chewing time/pig recorded. Oral fluid was extracted from all of the ropes. Rope provided for 60 min generated chewing in >80% of the group. Pigs in SK exhibited longer latency to interact with the rope (P<0.001), reduced percentage of pigs chewing (P<0.001), and a reduced mean total time spent chewing (P<0.001). An interaction was found between 'system' and 'number of ropes provided' (P<0.05). Increasing the number of ropes increased the mean total chewing time/pig only in the FS. The quantity of OF obtained correlated with the percentage of pigs that chewed the rope (P<0.001) and the mean total time spent chewing/pig (P<0.001). Where the group size was ≤25, presenting one rope for 45 min was sufficient to optimise the number of pigs sampled.
Currently virus surveillance in swine herds is constrained by the cost-effectiveness and efficiency of sampling methods. The objective of this study was to assess the value of using oral fluids collected by barn personnel as a method of surveillance based on PCR testing. Approximately 12,150 pigs in 10 wean-to-finish barns on 10 farms were monitored for the presence of porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), influenza A virus (IAV), and Torque teno virus genogroups 1 (TTV1) and 2 (TTV2) by sampling oral fluid specimens. Oral fluid samples were collected from 6 pens at each site starting at the time of pig placement (∼3 weeks of age) and continuing thereafter at 2-week intervals for a period of 18 weeks. Data were analyzed both on a pen basis and barn basis. Overall, 508 (85%) samples were positive for PCV2, 73 (12%) for PRRSV, 46 (8%) for IAV, 483 (81%) for TTV2, and 155 (26%) for TTV1 during the study period. The estimated arithmetic means of the quantitative PCR-positive oral fluids for PCV2, PRRSV, and IAV were 1×10(4.62), 1×10(4.97), and 1×10(5.49)per ml. With a single exception, all barns were positive for PCV2 and TTV2 at every sampling point in the study. Virus detection varied among barns, particularly for IAV and PRRSV. The pen level, cumulative distribution of agent combinations between all 10 barns were statistically different. The most commonly observed patterns were PCV2+TTV2 (239 pen samples, 40%), PCV2+TTV1+TTV2 (88 pen samples, 15%), and PCV2 alone (66 pen samples, 11%). This "proof-of-concept" project showed that a variety of viruses could be detected either intermittently or continuously in pig populations and demonstrated that barn herd virus status is highly variable, even among barns in the same production system. Oral fluid sampling is a promising approach for increasing the efficiency and cost effectiveness of virus surveillance in swine herds.