Does mixed-age weaning favor PRRSV circulation in the nursery?
In this study, batches from herds using mixed-age weaning had a substantially higher risk of PRRSV positivity than batches managed all-in/all-out.
In this study, batches from herds using mixed-age weaning had a substantially higher risk of PRRSV positivity than batches managed all-in/all-out.
Problem: Holding smaller pigs back and mixing them with younger batches may help sustain PRRSV circulation after weaning.
Methods: Three herds using mixed-age weaning were compared with three all-in/all-out herds using 260 oral-fluid samples from 23 batches plus tongue-tip samples from dead pigs.
1. Forty-one oral-fluid samples from eight batches in mixed herds were positive compared with five samples from two batches in all-in/all-out herds.
2. The risk of a PRRSV-positive batch was 8.4 times higher under mixed-age weaning than under all-in/all-out management (p<0.001).
3. Oral-fluid and tongue-tip results agreed in 17 of 23 batches (κ=0.44), but five of six discordant sampling events involved negative tongue tips with positive oral fluids, indicating that the matrices should not be regarded as fully interchangeable.
Original publication
Heiselberg PR et al. Impact of weaning procedures on PRRSV circulation in the nursery section. BMC Veterinary Research. 2025;21:206.