Table 2 Formulas for Key Predictor Indicators to calculate the impact of PRRS on reproductive performance in breeding herds

Abortions x 1000 sows (ABTHS)

(Nº abortions per week / Nº productive sows) x 1000

Born-Alive rate (BAR) (%)

(Nº born-alive piglets per week/

Nº of total born piglets^a per week) x 100

Pre-weaning mortality rate (PWMR) (%)

(Nº dead suckling piglets / Nº of total born-alive per week) x 100

Weaned piglets x 1000 sows

(WPTHS)

(Nº of weaned piglets per week/ Nº productive sows) x 1000