PRRS control in growing and finishing pigs

Vaccination and total or partial depopulation has been shown to be effective in the control of PRRS in growing and finishing pigs.

Vaccination

Before starting a vaccination programme it is very important to investigate when the infection is taking place. This means that vaccination can then be timed to enable protection of the pigs prior to the usual infection time. Serological monitoring is used for this purpose.

In a controlled field study with Porcilis PRRS it was shown that vaccination of finishing pigs at 6 weeks of age reduced the mortality from 7.5% to 3.4%. It increased the average daily gain from 602 g per day to 645 g per day and reduced the incidence of respiratory disease in the vaccinated pigs compared to the controls (Mavromatis, 1999). See Efficacy field trial - Greece.

Depopulation

Depopulation of nurseries and finishers should be done after cleaning up the sow herd. This ensures that the new, disease-free pig flow does not become infected by the older pigs. Before considering a depopulation strategy it is important to evaluate the chance for success and if the aim is eradication of PRRS virus, the risk of re-infection.

Dee (1997) has shown success with depopulation of nursery units using different depopulation protocols. PRRS virus was not eliminated with this strategy but the performance was improved.

In Denmark, success was achieved in eradication of PRRSV from finishing farms on four of five farms by using partial depopulation (Andreasen, 1999).