PRRS type 1 MLV mass vaccination in commercial sow herds is safe

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Rene Sol1; Sanne van Dieten1; Martijn Steenaert2

1VKC, The Netherlands; 2Boehringer Ingelheim Animal Health Netherlands bv

 

Introduction

Different PRRS vaccination protocols for sow herds in the Netherlands are used. Off all PRRSV MLV vaccinating sow herds roughly 40% uses whole herd mass vaccination (vaccination of all breeding stock 3-4 times a year) and 50% using a batch vaccination program (vaccination of breeding stock per batch in specific phases in the production cycle) (Hokdierscan; 2016). The main arguments not to use mass vaccination protocols are suspected productivity effects due to vaccination during critical phases of the sows’ reproductive cycle. In this study we compare production results in sow herds after PRRS type 1 MLV mass vaccination to the baseline production.

Material and Methods

Production data was retrospectively obtained from the farm management systems (Agrovision). In total 8 farms and 70 mass vaccination events using PRRS type 1 MLV vaccines were analyzed. Different registered PRRS type 1 MLV vaccines were used. Following the mass vaccination events we looked into: 1) the pregnancy rate at 35 days after insemination representing return to estrus, 2) farrowing rate, representing total pregnancy losses including abortions, and 3) the number of still born piglets per litter representing piglet quality. The baseline production was defined as the production results in the period up to 6 weeks prior to mass vaccination, the post-vaccination period was defined as the period up to 6 weeks following mass vaccination including the week of mass vaccination. We performed two types of analysis comparing baseline to post-vaccination production:

  • On a herd level Statistical Process Control (SPC) was used to identify weekly changes of more than 2 Standard Deviations (>2SD). The incidences of >2SD changes over the herds are expressed as average incidences per week.
  • Aggregated weekly data from all herds.

Results

Table 1 Image

Table 1: Incidence rate of negative production results per week of changes >2SD

Table 2 Image

Table 2: Aggregated production results after mass vaccination events in sow herds compared to baseline production

Discussion and Conclusion

In the aggregated data (table 2) there are no relevant differences in production results. The incidence rate of >2SD changes per week was generally low (table 1) and scattered evenly over the baseline and post vaccination periods (data not shown).

Whole herd vaccination advantages are a larger homogeneity in terms of immunity at population scale (Rose 2017), better herd immunity, less administration, lower number of missed vaccinations and reduced labor, and is seen as a ‘stupid proof’ vaccination scheme. Any presumed negative production results like return to estrus and birth of less quality piglets in the weeks following mass vaccinations may be more emotional than rational. Mass vaccination in individual sow farms was experienced with only transient and numerically small changes in productivity when using PRRS type 2 MLV (Moura;2019) or was found safe when using a PRRS type 1 MLV (Rathkjen;2016). We conclude that the PRRS type 1 MLV mass vaccination is safe and recommended for the control of PRRSV in a sow herd.

524 words

Keywords: PRRS MLV, mass vaccination, production results, vaccination protocol
Topic: Vaccination and immunology/ Herd management

References:

  1. Hokdierscan Marketing research; 2016
  2. Moura.2019.production impact following PRRS mass vaccination
  3. POSTER Rathkjen IPVS 2016 Data confirming confidence in Whole Herd mass vaccination program with Novel PRRS Type 1 MLV
  4. Rose.2017.use of vaccines to control pathogen spread in pig populations