Search

Air filtration systems implemented in large sow herds have been demonstrated to decrease the probability of having a porcine reproductive and respiratory syndrome virus (PRRSV) outbreak. However, implementation of air filtration represents a considerable capital investment, and does not eliminate the risk of new virus introductions. The specific objectives of the study were: 1) to determine productivity differences between a cohort of filtered and non-filtered sow farms; and 2) to employ those productivity differences to model the profitability of filtration system investments in a hypothetical 3000 sow farm. Variables included in the study were production variables (quarterly) from respective herds; air filtration status; number of pig sites within 4.7 km of the farm; occurrence of a PRRSV outbreak in a quarter, and season. For the investment analyses, three Scenarios were compared in a deterministic spreadsheet model of weaned pig cost: (1) control, (2) filtered conventional attic, and (3) filtered tunnel ventilation. Model outputs indicated that a filtered farm produced 5927 more pigs than unfiltered farms. The payback periods for the investments, were estimated to be 5.35 years for Scenario 2 and 7.13 years for Scenario 3 based solely on sow herd productivity. Payback period sensitivity analyses were performed for both biological and financial inputs. The payback period was most influenced by the premium for weaned pig sales price for PRRSV-negative pigs, and the relative proportions of time that filtered vs. unfiltered farms produced PRRSV-negative pigs. A premium of $5 per pig for PRRS-negative weaned pigs reduced the estimated payback periods to 2.1 years for Scenario 2 and 2.8 years for Scenario 3., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Standardized terminology for the porcine reproductive and respiratory syndrome virus (PRRSV) status of swine herds is necessary to facilitate communication between veterinarians, swine producers, genetic companies, and other industry participants. It is also required for implementation of regional and national efforts towards PRRSV control and elimination. The purpose of this paper is to provide a herd classification system for describing the PRRSV status of herds, based upon a set of definitions reflecting the biology and ecology of PRRSV. The herd classification system was developed by a definitions committee formed jointly by the American Association of Swine Veterinarians (AASV) and the United States Department of Agriculture PRRS-Coordinated Agricultural Project, and was approved by the AASV Board of Directors on March 9, 2010. The committee included veterinarians from private practice and industry, researchers, and representatives from AASV and the National Pork Board. Breeding herds, with or without growing pigs on the same premises, are categorized as Positive Unstable (Category I), Positive Stable (Category II), Provisional Negative (Category III), or Negative (Category IV) on the basis of herd shedding and exposure status. Growing-pig herds are categorized as Positive or Negative. Recommended testing procedures and decision rules for herd classification are detailed.

A variety of methods for eliminating the PRRS virus from pig production sites have been successfully applied. However, success in maintaining a PRRS virus-free status for extended periods of time following elimination has been inconsistent and unpredictable. The objective of this study was to evaluate whether risks measured using version 1 of the American Association of Swine Veterinarians (AASV) PRRS Risk Assessment for the Breeding Herd, season of year and method by which swine breeding herd sites were established PRRS virus-free were associated with how long they retained their virus-free status. Thirty-three swine farrow-to-wean breeding herd sites that were established as PRRS virus-free by either populating a new site with virus-free breeding animals or by completely depopulating the site and repopulating with PRRS virus-free breeding animals were enrolled in this study. Survival analysis, using the Cox proportional hazards model and Kaplan-Meier survival curves, was performed where the outcome was the duration of time PRRS virus-free breeding herd sites remained virus-free ("survived"). Covariates evaluated included the internal and external risk scores measured by the PRRS Risk Assessment for the Breeding Herd as well as the season and the method by which the site was established free of the PRRS virus. All but 5 (15%) of the 33 sites became positive to the PRRS virus during the course of the study and approximately 40% became positive within 1 year from when they were established free of the PRRS virus. A higher external risk score was associated with a greater risk of becoming positive to the PRRS virus and shorter survival times. The internal risk score was not significantly associated with survival. Establishing breeding herd sites free of the PRRS virus in winter months (November through February) was associated with a greater risk of becoming positive to the PRRS virus and shorter survival times compared to those established in non-winter months. The association between the risk of becoming positive to the PRRS virus and the external risk score was confounded by the method the site was established PRRS virus-free., (2010 Elsevier B.V. All rights reserved.)

Porcine reproductive and respiratory syndrome (PRRS) continues to be one of the most significant diseases of swine. IDEXX HerdChek PRRS, a commercially available enzyme-linked immunosorbent assay (ELISA), has become the industry standard for the detection of antibodies against PRRS virus (PRRSV). The need to accurately determine the PRRSV serostatus of herds and individual animals has prompted the development of several follow-up assay methods. A highly specific and repeatable blocking ELISA (bELISA) was developed on the basis of the use of an expressed PRRSV nucleocapsid (N) protein as the antigen and a biotinylated monoclonal antibody. Validation of the bELISA used sera from 316 animals experimentally and naturally infected with North American PRRSV and sera from 370 uninfected animals. Receiver operating characteristic analysis of the data calculated a diagnostic sensitivity of 97.8% and a diagnostic specificity of 100%. The between-run coefficient of variation of an internal quality control serum was 4.24%. The bELISA was able to detect seroconversion as well as the IDEXX ELISA and the indirect fluorescent antibody (IFA) assay; kappa values were 0.94 and 0.96, respectively. A collection of 133 serum samples with unexpected positive IDEXX ELISA results was obtained from 4,038 diagnostic samples submitted from farms from which PRRS-negative results were expected. The bELISA identified 97% of the samples as PRRS seronegative, while the IFA identified 100% as seronegative. The anticipated use of the bELISA is as a follow-up test to the IDEXX ELISA for determining the PRRSV serostatus of individual animals with unexpected positive test results from swine herds from which negative results are expected.

Neonatal pigs from three herds of pigs were somnolent and inappetent and had microscopic lesions characterised by severe meningoencephalitis, necrotic interstitial pneumonia and gastric muscular inflammation. Porcine reproductive and respiratory syndrome virus (PRRSV) infection was diagnosed and confirmed by virus isolation, fluorescent antibody examination of frozen lung sections, serology, immunohistochemistry and in situ hybridisation. Each herd had a history of PRRSV infection and was using or had used a modified-live vaccine. The isolates from the affected pigs were genetically distinct from the modified-live vaccine strain of the virus when compared by restriction enzyme analysis and nucleotide sequencing of PRRSV open reading frames 5 and 6. The virus was identified in macrophages or microglia of brain lesions by immunohistochemical staining of brain sections with an anti-PRRSV monoclonal antibody and an anti-macrophage antibody. The replication of the virus in the brain was verified by in situ hybridisation. The meningoencephalitis induced by the virus in pigs from each of the herds was unusually severe and the brain lesions were atypical when compared with other descriptions of encephalitis induced by the virus, which should therefore be considered as a possible diagnosis for neonatal pigs with severe meningoencephalitis. In addition, field isolates of the virus which are capable of causing disease can emerge and coexist with modified-live vaccine virus in some pig herds.

The financial impact of nursery depopulation was assessed on 34 pig farms by constructing a partial budget model to measure the profitability of the nursery production. The model measured margin over variable cost and used production data generated from a previous study; it assumed that fixed costs remained constant throughout the study and that feed cost, weaned pig cost and market price per nursery pig also remained fixed. The mean margin over variable cost per sow on the 34 farm after nursery depopulation was Pounds 116. Thirty-two of the farms showed reductions in this cost, ranging from Pounds 20 to Pounds 408 per sow, in the 12 months after nursery depopulation compared with the previous 12 months. Of the two farms which did not show an increase in profitability, one showed no change and the other showed a net loss of Pounds 8 per sow. The sows' serostatus for porcine reproductive and respiratory syndrome virus infection was monitored but there was no significant difference between the margin over variable cost per sow of the seropositive (Pounds 130) and seronegative (Pounds 170) herds.

Nursery depopulation has been described as an effective strategy for improving the performance of weaned pigs. In order to assess whether the strategy was effective under a wide range of conditions, a study was carried out on 34 farms in the USA. Four groups with different depopulation protocols were designed on the basis of the location of the depopulated facility (on site vs off site) and the period for which the nursery remained empty (seven days vs 14 days). The changes in average daily liveweight gain, percentage mortality, feed efficiency and treatment cost per pig produced were assessed 12 months before and after nursery depopulation. The ability to eliminate porcine reproductive and respiratory syndrome (PRRS) virus was examined by indirect fluorescent antibody testing of the nursery pigs. Significant improvements (P < 0.0001) were detected in both average daily gain and percentage mortality after depopulation when the differences within an individual group were analysed, but no significant differences (P > 0.14) were observed between the study groups. Serological testing indicated that antibodies to PRRS virus were still present in 14 of the 34 farms after depopulation.

A more rapid, accurate method to detect toxigenic Pasteurella multocida is needed for improved clinical diagnosis, farm biosecurity, and epidemiological studies. Toxigenic and nontoxigenic P. multocida isolates cannot be differentiated by morphology or standard biochemical reactions. The feasibility of using PCR for accurate, rapid detection of toxigenic P. multocida from swabs was investigated. A PCR protocol which results in amplification of an 846-nucleotide segment of the toxA gene was developed. The PCR amplification protocol is specific for toxigenic P. multocida and can detect fewer than 100 bacteria. There was concordance of PCR results with (i) detection of toxA gene with colony blot hybridization, (ii) detection of ToxA protein with colony immunoblot analysis, and (iii) lethal toxicity of sonicate in mice in a test set of 40 swine diagnostic isolates. Results of an enzyme-linked immunosorbent assay for ToxA agreed with the other assays except for a negative reaction in one of the 19 isolates that the other assays identified as toxigenic. In addition to accuracy, as required for a rapid direct specimen assay, toxigenic P. multocida was recovered efficiently from inoculated swabs without inhibition of the PCR. The results show that PCR detection of toxigenic P. multocida directly from clinical swab specimens should be feasible.

An attempt was made to compare the productivity and financial benefits of nursery depopulation on five large pig farms which were all part of one complex. Each farm had been experiencing poor post weaning performance for 12 months, and had previously been infected with porcine reproductive and respiratory syndrome virus (PRRSV). A plan to depopulate each nursery sequentially was established, and the pigs were moved to fattening facilities on one of the farms (farm 3) where space was available. Over a four week period, the nurseries of farms 1, 2, 4 and 5 were emptied, cleaned and disinfected, and any changes in nursery performance, mortality and the seroprevalence of antibodies to PRRSV were then assessed for one year. The financial benefit to the entire farm complex was analysed by using partial budget methods. During the year a net benefit of $1,708,431 was assessed to the farm complex owing to the increased numbers of marketable pigs and the reduced antibiotic costs. There were highly significant improvements in nursery growth rate and decreases in mortality on farms 1, 2, 4 and 5, and antibodies to PRRSV were detected on farms 3 and 4 but not on farms 1, 2 and 5. The inability to empty the farm 3 fattening facility, which housed the pigs from the other sites, may have led to the maintenance of its PRRSV positive status and could have served as the source of virus for farm 4.

As the swine industry continues to evolve and develop a greater business orientation--one that demands justification of costs, benefits, and risk-exposure--the veterinarian will be confronted with the need to develop an economic basis to supplement the biologic. The profession should view such a challenge as an opportunity to broaden its role in serving the businesses that make up the industry. However, to be effective in such an expanded role requires that the veterinarian develop a good working knowledge of risk and risk management as well as the role played by economic evaluation techniques used in financial evaluation in the risk management process. Several potential advantages exist for the veterinarian who determines to expand his or her risk management role by using financial evaluation in the course of day-to-day practice routine: Additional service or consulting income may be generated through evaluating alternatives through decision analysis. Client confidence may be strengthened in the veterinarian and in the recommendations made. The costs of consulting services and health products for the client may be viewed as income-generators instead of being viewed solely as expenses. Referrals of additional progressive clients may be generated by satisfied current clients. The veterinarian may achieve personal satisfaction through substantiating his or her recommendation beyond clinical or experimental judgment. With the capability of using financial evaluation techniques in the evaluation and justification of recommendations comes significant responsibility. Reliance upon financial evaluation techniques as a more objective approach in the management of risk for clients carries with it an inherently greater degree of trust. Such trust must be deserved. The universal adage "garbage in, garbage out" applies directly to financial evaluation. Financial evaluation techniques have the potential to provide the decision-maker with objective and accurate analysis, improving the probability of choosing an optimal course of action for the business. However, the objectivity and accuracy achievable is highly dependent upon the quality and quantity of information used in the analysis. Veterinarians must be cognizant of the increased responsibility demand placed on those using financial evaluation techniques to direct the course of action for their clients. Financial evaluation tools are available to decision-makers that may improve the objectivity of the decision-making process, providing for a greater degree of confidence in the expected outcome. Stated another way, these tools can reduce the number of surprises a decision-maker encounters as a result of the decisions made.(ABSTRACT TRUNCATED AT 400 WORDS)

The rate-limiting phase of commercial swine production is breeding. The design of the breeding/gestation facilities influences the capacity of the producer to efficiently manage the breeding stock around the time of service and during the postservice period. Thus, breeding design potentially affects total born litter size and farrowing rates. In general, with original construction and facility renovation, the three principal activities of the breeding/gestation phase of production, (1) boar exposure/estrus detection, (2) breeding, and (3) gestation and pregnancy detection, should be independently considered.