Naïve or Not? The Never-Ending Dilemma of Sow Farm PRRS Status

(National Pork Board and the Pork Checkoff)

By Melissa Hensch, DVM

As porcine reproductive and respiratory syndrome (PRRS) viruses continue to evolve, producers are often faced with a difficult decision regarding the sow farm’s long-term PRRS status. While it is best for the production system to avoid PPRS, trying to manage the disease has become more and more difficult, even with significant investment in biosecurity practices.

In the past 12 months, we have broken several naïve sow farms with a long history of no previous breaks, encompassing greater than 10% of our sow base. The production impacts on both the sow and wean-to-market performance have varied greatly from farm to farm, but consistently trended towards severe.  

These breaks have pushed forward a discussion on the best strategy for our sow herds from a PRRS perspective. The two ideal statuses of sow herds are naïve or vaccinated but producing negative wean pigs (2V). It has been well documented that if a sow farm breaks with PRRS, a 2V farm will have significantly reduced impact on performance and improved throughput through the break. However, there are challenges with running a sow farm 2V such as gilt management, piglet performance and increased cost. 

Evaluate the impact of your farm status
As we consider what status to run a farm, we must consider the full production scope and picture for both the sow farm and growing phase of production. Items that lead us down one path or another on the sow farm side include: area risk and PRRS break rate history, risk to other negative farms in the area including multiplication and boar studs, and the ability to PRRS vaccinate gilts prior to entry into the sow farm. 

The side with less data to support decision making on true impact, but potentially a much bigger impact, could be wean-to-market (WTM). Here we primarily consider where we are going to place and ultimately finish the piglets weaned from the sow farm. If that is an area with a lot of PRRS pressure and likelihood that the WTM pig will see PRRS, then there is an unmeasured benefit of having a piglet with PRRS immunity, in addition to the possibility of vaccinating that piglet at the sow farm for PRRS. 

Challenge your thought process
New strains of PRRS that have caused extreme clinical signs such as 100% pre-wean mortality in piglets for multiple weeks in a row, in addition to much higher area spread than has been historically normal, are pushing us to challenge our above thought process on the best fit long term. If we can keep sow farms PRRS naïve, and place and keep their piglets PRRS naïve, then the solution is easy – stay negative! 

However, we are currently facing the challenge of balancing and supporting our business with consistent throughput, in addition to a very complex situation that is farm and flow-specific that will drive this decision. The short-term picture has led us to turn several sow farms to a 2V status. 

While the long-term picture remains to be seen on additional farms, we are heavily challenging our thought process on which sow farms are the best fit for running PRRS naïve, which could lead to additional 2V farms. Landing this strategy prior to disease season will be critical for fiscal year 2022 and beyond, so stay tuned.

More from Farm Journal's PORK:

A Recipe for Innovation Success in the Pork Industry

The Responsibility Paradox and Pig Farming

4 Things to Consider When Handling Heavier Market Hogs 

 

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