Impact of Test Sensitivity and Specificity on Pig Producer Incentives to Control Mycobacterium avium Infections in Finishing Pigs07 August 2013
Dutch scientists have been looking into the characteristics of a test for Mycobacterium avium with the view to eliminating the bacterium from pig farms.
Test sensitivity and specificity for Mycobacterium avium (Ma) must be considered in incentive systems design to induce pig producers to control Ma in finishing pigs with minimum negative effects, concluded Coen van Wagenberg of the LEI Wageningen UR and co-authors in a paper published online in Preventive Veterinary Medicine.
Together with researchers from the Central Veterinary Institute, Operations Research and Logistics Group and Animal Nutrition Groups of Wageningen UR, the impacts of the sensitivity and specificity were analysed of an Ma test on pig producer incentives to control Ma in finishing pigs.
A possible Ma control system which includes a serodiagnostic test and a penalty on finishing pigs in herds detected with Ma infection was modelled.
Using a dynamic optimisation model and a grid search of deliveries of herds from pig producers to slaughterhouse, optimal control measures for pig producers and optimal penalty values for deliveries with increased Ma risk were identified for different sensitivity and specificity values.
Results showed that higher sensitivity and lower specificity induced use of more intense control measures and resulted in higher pig producer costs and lower Ma seroprevalence.
The minimal penalty value needed to comply with a threshold for Ma seroprevalence in finishing pigs at slaughter was lower at higher sensitivity and lower specificity, the researcher found. With imperfect specificity, a larger sample size decreased pig producer incentives to control Ma seroprevalence because the higher number of false positives resulted in an increased probability of rejecting a batch of finishing pigs irrespective of whether the pig producer applied control measures.
van Wagenberg C.P.A., G.B.C. Backus, H.J. Wisselink, J.G.A.J. van der Vorst and B.A.P. Urlings. 2013. Impact of test sensitivity and specificity on pig producer incentives to control Mycobacterium avium infections in finishing pigs. Preventive Veterinary Medicine, 111(3–4):286–296.
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