- P. Alexandri (1)
- H. Feitsma (1)
- R.W. Hakze-van der Honing van der (1)
- J. Herrero-Medrano (1)
- C.E. Jacobs (1)
- E.F. Knol (1)
- P.K. Mathur (1)
- P.L.J.M. Moonen (1)
- H.A. Mulder (1)
- J. Napel ten (1)
- H. Rashidi (1)
- P.A. Rijn van (1)
- G.J. Wellenberg (1)
Estimating challenge load due to disease outbreaks and other challenges using reproduction records of sows
Mathur, P.K. ; Herrero-Medrano, J. ; Alexandri, P. ; Knol, E.F. ; Napel, J. ten; Rashidi, H. ; Mulder, H.A. - \ 2014
Journal of Animal Science 92 (2014)12. - ISSN 0021-8812 - p. 5374 - 5381.
environment interaction - breeding programs - respiratory syndrome - genotype - pigs - cattle - models
A method was developed and tested to estimate challenge load due to disease outbreaks and other challenges in sows using reproduction records. The method was based on reproduction records from a farm with known disease outbreaks. It was assumed that the reduction in weekly reproductive output within a farm is proportional to the magnitude of the challenge. As the challenge increases beyond certain threshold, it is manifested as an outbreak. The reproduction records were divided into 3 datasets. The first dataset called the Training dataset consisted of 57,135 reproduction records from 10,901 sows from 1 farm in Canada with several outbreaks of porcine reproductive and respiratory syndrome (PRRS). The known disease status of sows was regressed on the traits number born alive, number of losses as a combination of still birth and mummified piglets, and number of weaned piglets. The regression coefficients from this analysis were then used as weighting factors for derivation of an index measure called challenge load indicator. These weighting factors were derived with i) a two-step approach using residuals or year-week solutions estimated from a previous step, and ii) a single-step approach using the trait values directly. Two types of models were used for each approach: a logistic regression model and a general additive model. The estimates of challenge load indicator were then compared based on their ability to detect PRRS outbreaks in a Test dataset consisting of records from 65,826 sows from 15 farms in the Netherlands. These farms differed from the Canadian farm with respect to PRRS virus strains, severity and frequency of outbreaks. The single-step approach using a general additive model was best and detected 14 out of the 15 outbreaks. This approach was then further validated using the third dataset consisting of reproduction records of 831,855 sows in 431 farms located in different countries in Europe and America. A total of 41 out of 48 outbreaks detected using data analysis were confirmed based on diagnostic information received from the farms. Among these, 30 outbreaks were due to PRRS while 11 were due to other diseases and challenging conditions. The results suggest that proposed method could be useful for estimation of challenge load and detection of challenge phases such as disease outbreaks.
Detection of economically important viruses in boar semen by quantitative RealTime PCRtm technology
Rijn, P.A. van; Wellenberg, G.J. ; Hakze-van der Honing, R.W. van der; Jacobs, C.E. ; Moonen, P.L.J.M. ; Feitsma, H. - \ 2004
Journal of Virological Methods 120 (2004)2. - ISSN 0166-0934 - p. 151 - 160.
mouth-disease virus - linked-immunosorbent-assay - polymerase chain-reaction - swine-fever virus - respiratory syndrome - artificial-insemination - transmission
The objective of this study was to develop quantitative real-time polymerase chain reaction (ReTi-PCR) tests for the detection of five economically important viruses in swine semen namely, pseudorabies virus (PRV), classical swine fever virus (CSFV), foot-and-mouth disease virus (FMDV), swine vesicular disease virus (SVDV), and porcine reproductive and respiratory syndrome virus (PRRSV). Each ReTi-PCR test was validated for specificity, analytical sensitivity (detection limits), and experimental infection studies were performed to compare the conventional virus isolation methods with the newly developed ReTi-PCR tests. All five developed ReTi-PCR tests are very rapid compared to virus isolation, highly specific, and even more sensitive (lower detection limits) than conventional virus isolation methods for the detection of mentioned viruses in semen. In semen of experimentally infected boars, viruses were detected much earlier after infection and more frequently by ReTi-PCR tests than by virus isolations. The high throughput of these rapid ReTi-PCR tests makes it possible to screen large number of semen samples for the presence of viruses prior to insemination. This is a substantial advantage, in particular for boar semen the quality of which deteriorates quickly after storage. In general, the newly developed ReTi-PCR tests are valuable tools for the early, reliable and rapid detection of five economically important viruses, namely PRV, CSFV, FMDV, SVDV, and PRRSV in boar semen. These ReTi-PCR tests will improve the control of viral diseases transmitted via semen. (C) 2004 Elsevier B.V. All rights reserved.