PRRSv infection in France: clinical and economic impact

Porcine reproductive and respiratory syndrome (PRRS) is a disease that is believed to have a big impact on the pig farms' productivity. As everybody knows, it is really difficult to measure the impact of the disease at the herd level precisely, because many parameters need to be considered:

• The kind of farm: Farrow-to-wean? Farrow-to-finish? Wean and finish? Finisher?
• The previous PRRS status on the farm: do we mean the cost of an infection in a naïve population or the cost of the chronic infection?
• The dynamics of PRRS circulation: if the farm is chronically infected, is it stable or unstable?
• The overall health status on the farm: PRRS has a lower clinical impact on a Mycoplasma hyopneumoniae-free than in a Mycoplasma hyopneumoniae-infected farm.

In this article we will try to give readers a picture of the cost of PRRS in French conditions, based on 3 studies performed in the last few years.

1. In 2005, ACERSA, a French national organization, estimated the cost of the introduction of the PRRS virus on a naïve farm as being of €30 per sow in the breeding herd due to reproductive failure, abortions and mortality in the farrowing quarters. In the post-weaning and finishing stages, due to the impact on the mortality rate, FCR and ADG, PRRS costs €84/sow. So, on a French naïve farm, the overall cost of the PRRS virus introduction seemed to be around €114/sow during the first year after the farm infection.

2. Another recent study was conducted by the OVS (Health Surveillance Organization) of Brittany in 2007. The economic impact of the PRRS circulation has been calculated by comparing 22 farms:

• 6 negative farms
• 6 with a low PRRSV infection status (farms with a vaccination programme in sows and no PRRSV circulation in the post-weaning piglets, and with irregular PRRS circulation in finishing pigs).
• 6 with a high PRRSV infection status (farms with or without a vaccination programme in sows, and PRRSV circulation in all the tested batches in finishing and sometimes in post-weaning piglets).

The parameters studied were FCR and ADG from weaning to slaughter, the number of weaned piglets/sow/year, the number of pigs produced/sow/year, the number of total born piglets, the mortality percentage in the post-weaning and finishing stages, and the cost of the veterinary services and medication per 100 kg of carcass weight. The results of the aforementioned study are summarized in Table 1.

Table 1: Mean 'PRRS cost' per sow and year, or per 100 kg of carcass weight per year, on 6 farms with a low PRRSV infection status and on 6 farms with a high PRRSV infection status, as compared to 6 PRSS-free farms free (OVS of Brittany 2007). CI: confidence interval

3. We have measured the economic impact of a PRRS stabilization protocol (and subsequently the cost of PRRS) on one of the farms tended to by our practice.

The study was carried out on a 452-sow, farrow-to-finish farm in Brittany that used a 10 batches system (weaning at 21 days and farrowing every two weeks). Gilts were purchased at 110 kg and quarantined for seven weeks before entering the herd.

After the PRRSV infection diagnosis, at the end of 2010, we implemented a stabilization protocol between May and December 2011. The following measures were applied:

• A 4-week interval mass vaccination of the entire herd for two times (sows, post-weaning and finishing pigs) with a MLV
• A vaccination of the successive batches of piglets after weaning for two times and during 20 weeks with a MLV
• An improvement of the internal biosecurity measures, especially the pig and human flow, hygiene, use of individual needles and gilts' acclimation.

In order to know the return of investment, we have calculated the economic impact by measuring the economic gain in terms of productivity and the global FCR improvement.

To do this we have standardized the price of feed and of the kg of sold pig with the average of these parameters between 2010 and 2012.

So in Table 2 you can see the total carcass weight produced before and after the stabilization programme, and the evolution of the variable costs: feed consumed and medication costs (including the cost of the PRRS vaccination protocol, estimated to be €18,000). So, the margin was estimated by calculating the difference between the sales and the variable costs (feed and health costs).

Despite the high cost of the PRRSv vaccination programme (€40/sow in 2011), we saw a return on investment since the year of the PRRS stabilization thanks to the improvement in both herd productivity and feed conversion. In this herd, the economic impact of the PRRSv circulation was estimated to be of €185/sow.

Table 2: Economic impact of PRRS calculated through the return of investment of a stabilization protocol

Conclusion and discussion

It is quite difficult to talk about the PRRS infection cost because, even in the same country, the kind of herd and its health status, and the PRRS virus dynamics differ from one farm to another. It is really difficult to standardize such a calculation. In the 3 studies presented, the PRRS cost ranged from €17 to €185/sow/year!