Genetic parameters for commercially important traits on a farm infected with porcine reproductive and respiratory syndrome (PRRS) virus: Can we use selection to help solve the PRRS problem?

Porcine reproductive and respiratory syndrome (PRRS) is the most economically important viral disease in pig populations worldwide with total associated costs to the US swine industry estimated at $560 million annually. Epidemiological models have been applied to PRRS and have demonstrated that selection for resistance can impact on reducing the likelihood of epidemics. Key components of selection programs for disease resistance are the characterisation of genetic variation and the identification of genetic markers or QTL associated with any resistance to, or tolerance of, the pathogen. The growing evidence for genetic variation in host susceptibility to PRRSV has been fully described in the review by Lewis et al. Using data collected from commercial pigs on a PRRS infected farm, this study seeks to quantify genetic variation in commercially important traits during both healthy and disease-affected phases.