Results of PRRS control in Dutch finisher farm after outbreak of PRRS

The objective of this study was to evaluate the effect of a PRRS vaccination under field conditions at a PRRS positive farm with finisher pigs.


Article by:

L. van Ampting

Vetpractice Lintjeshof, Nederweert, The Netherlands


PRRS infections can have a significant effect on the technical performance in pigs in the nursery and finisher farm. PRRS-positive farms were associated with a significantly higher risk for pneumonia and lower growth1. The impact in the finishing phase in the Netherlands is calculated on a growth loss around 60 gram / day and a 0,15 FCR increase2. The objective of this study was to evaluate the effect of a PRRS vaccination under field conditions at a PRRS positive farm with finisher pigs.

Materials and methods

This case study was performed in a finishing farm of 3500 finishing places. The farm received since years the piglets from a 400 sow farm (T20 x Talent), which had a long proven history of selling PRRS negative piglets. The piglets were vaccinated at 3 weeks of age against PCV2 (CircoFLEX®, Boehringer Ingelheim) for years; in January 2016 this was combined with MycoFLEX in a 2 ml 1 shot at 3 weeks of age. Due to an acute outbreak of PRRS in February 2016 in the sow farm (resulting in significant reproductive losses and weakborn piglets for months), the finishing farm received shortly afterwards PRRS positive pigs. PRRS was diagnosed by PCR on 10 week old piglets. The PRRS strain had an 86 % homology on ORF 5 compared with Lelystad PRRS virus. The problems in the finishing barn consisted of increased respiratory problems, higher use of antibiotics due to secondary bacterial infections, decreased growth, less uniform pigs and higher feed conversion rate. In August 2016 the sow farmer started with a piglet vaccination against PRRS (PRRSFLEX® EU, Boehringer Ingelheim) at 3 weeks of age, applied in a 2 ml triple combination with the FLEXcombo® mixture (off label).
The economical relevant production parameters were used for evaluation. Monthly close out data records from the finishing barns were retrospectively collected from June 2015 until August 2017 for the 3 different periods (before PRRS outbreak – outbreak pigs non-vaccinated – PRRS vaccinated pigs). For evaluation and comparison of the antibiotic use, the standardized method of Defined Daily Dosages (DDD) of antibiotics used per animal year was applied3,4.


The PRRS outbreak had a negative effect on all the economical relevant parameters of the pigs on this farm. In the time frame with the added PRRS vaccination the general health improved resulting in less coughing, better uniform pigs, and less losses until slaughter. All the major production parameters improved (see table 1 and figure 1). Also the DDD decreased below the legal target threshold.

Table 1: Technical results of finisher pigs for the 3 different period



PRRS outbreak pigs


slaughter periods

june 15 – 16

july – dec 2016

jan – aug 2017

vaccination protocol piglet

circo (myco)

circo - myco

circo - myco - prrs

mortality %




growth / day (g)*








mm fat




mm muscle








average days at finishing




* corrected data for 25 – 112 kg

Figure 1: Average daily growth (gram / day) for the 3 different periods in time

Figure 1: Average daily growth (gram / day) for the 3 different periods in time

Discussion and conclusion

This retrospective analysis of a Dutch pig farm confirms that the PRRS vaccine in combination with vaccination against Mycoplasma hyopneumonia and PCV2 improved not only the clinical symptoms but also the technical performance of the pigs. This is in line with other reports5-7. The biggest improvements in clinical en technical results are visible from January 2017 due to the PRRS vaccination. A new feed supplier was implemented in the finishing phase in the beginning of 2017. The possible effects of this on technical results are visible in the figures from May 2017 onwards. SPC-charting of production data is a useful way to follow changes in performance in a before after setting.


  • 1. Jansen IPVS 2016 p131
  • 2. Jansen IPVS 2016 p562
  • 3. SDA. Bos et al. PLoS One. 2013;8(10):e77525.
  • 4. Maran 2016
  • 5. Kirwan Leman 2017
  • 6. Von dem Busche, ESPHM 2017 p318
  • 7. Figueras, ESPHM 2017 p423