- 1 minute, 46 seconds
- Expertise article
- Valérie Normand, Arnaud Lebret, Ingrid Messager, Céline Chevance, Franck Bouchet et. al.
INTRODUCTION
The aim of the study was to calculate the time to PRRSv-stability (TTS), the time-to-baseline-production (TTBP) and total losses in a European context after implementing a PRRS stabilization plan.
MATERIALS & METHODS
Herd included:
- 1000 sows, farrow-to-wean farm conducted in 10 batches (farrowing each 2 weeks, weaning age at 21 days).
- Previously naive herd. Contaminated by a PRRSv-1 strain in January 2018.
PRRSv stabilization plan:
- Mass vaccination with REPROCyc® PRRS EU (2ml, IM) of all the sows twice, one month apart
- Herd closure during 8 weeks
- Strict internal biosecurity measures
Assessment of herd stability:
PCR tests on 30 due-to-wean piglets’ serum (1/litter) and collective oral fluid of the same 30 litters in 3 different batches, starting 12 weeks after the first mass vaccination and monthly. Beginning the sampling 12 weeks after a stabilization program is a common practice in France1 in order to avoid “interference” with a hypothetical spread of the vaccine strain. Statistical analysis was performed using SAS 9.2 software.
TTS is defined as the time in weeks taken to produce PRRSv negative piglets. Day 1 was the day of the 1st mass vaccination.
TTBP is defined using statistical process control methods to represent time to recover the number of pigs weaned per batch that the herd had before PRRSv contamination. The data from the 20 batches prior to the outbreak were used as baseline data. A kappa (weight) of 0.400 and 3 sigma were used to define the control limits2.
Total losses was measured by the number of pigs not weaned per 1000 sows between the time of PRRSv detection until TTBP was reached2.
RESULTS TTS was 22 weeks.
TTBP was 7.66 weeks.
Total losses were 2421.7 piglets.
Figure: Evolution of the number of weaned piglets per batch. The farm recovered the baseline production level after 7.66 weeks
CONCLUSION This study is the first one, to our knowledge, aiming to calculate TTS, TTBP and total losses in a European context. Face to a PRRSv-1contamination in a naïve herd, TTS and TTBP were below those previously described in the US after a PRRSv-2 outbreak but total losses calculation was similar2, 3 , 4.
The monitoring of the stability was initiated 12 weeks after the 1st mass vaccination and stability was immediately reached. It could be interesting to start the evaluation of TTS earlier.
