[Terminology for classifying the porcine reproductive and respiratory syndrome virus (PRRSV) status of swine herds]. / Terminologie zur Klassifizierung des PRRSV-Status von Schweineherden.

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.

Porcine reproductive and respiratory syndrome virus infection in neonatal pigs characterised by marked neurovirulence.

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.

Evaluation of the effects of nursery depopulation of the profitability of 34 pig farms.

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.

Evaluation of the effects of nursery depopulation on the persistence of porcine reproductive and respiratory syndrome virus and the productivity of 34 farms.

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.

Direct PCR analysis for toxigenic Pasteurella multocida.

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.

Improved performance of a large pig complex after sequential nursery depopulation.

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.

Breeding and gestation facilities for swine. Matching biology to facility design.

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.

Financial evaluation and decision making in the swine breeding herd.

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)