Strain dynamics, time of year, gilt sources and multiplication all influence decisions.

Ann Hess, Content Director

August 30, 2022

5 Min Read
Eliminating PRRSV from multipliers
National Pork Board

When it comes to eliminating porcine reproductive and respiratory syndrome virus from The Maschhoffs' breeding herds, Amy Maschhoff says there are several influencers the pork production system considers before making any decisions. The first being strain dynamics.

"We are the producer that calls and says, 'hey what is this virus doing for others, what is it doing for production, what's the abortion rate, what's the nursery impact going to be?'" says Maschhoff. "Because as a production system, at some point, we've got to take those factors into play."

The associate director of health for The Maschhoffs recently shared her experience eliminating PRRSV from multipliers during the recent PRRSV Management Workshop in Iowa and says sending in processing fluid and serum samples has helped in the decision-making progress.

"The other things that we look at is what's happened historically within our system, so if we've had some herds that have broken this year with aspecific strain," Maschhoff says. "We can say 'okay what happened in those herds? Were those breaks connected? Do those RFLP patterns match, what happened in this herd and how do we want to manage it differently in this next herd that broke four weeks later because of some biosecurity breach that occurred.'"

Another objective they consider in PRRSV decision making are timelines.

"What does our time to baseline production look like, and what does it look like for our system to manage it, with herds taking longer and longer to eliminate the virus than they did several years ago," Maschhoff says.

Examining time of year is also essential.

"As a production company, things that are going to come into play when we're talking to our financial analysis team is going to be what's cull sow prices? What are Grade A futures of those wean pigs coming out of our herds going to be based on?" Maschhoff says. "What time of the year ourherd break impacts not only a production decision but an economic decision and how we're going to manage those closures within the system."

Maschhoff says the system has decided to make a few more decisions regarding depopulation over the last year, specifically due to the advantageous cull sow prices in the current market

The region of a PRRSV outbreak is another important influencer for the pork production system. Biosecurity through bioexclusion and biocontainment must be conducted. Area pressure from other herds and other producers' herds must be examined.

"We have sow farms that are connected with others, whether it be through feed, transport, labor resources, supply delivery, you name it, so if we're going to choose between that depop/repop or an elimination, that biocontainment process decisions influence how we're going to manage those herd managment decisions so that we can just get that virus frankly out of that pod of sow farms when needed," Maschhoff says.

Other factors that come into play are pig flow. The Maschhoffs' pork production system not only includes sow farms but also many wean-to-market production partners.

"So, where are we going to place growing populations of pigs if that herd is a wean pig stable negative farm or a positive farm comes into play. The wean-to-market impact and the space allocations of it we also consider when we're thinking about how we're going to manage our PRRS decisions across the system," she says.

For farms where they manage their own gilt sources and parent stock, the pork production system must decide whether they can manage the break or if they will have to utilize other genetic sources outside of their multipliers and the short and long-term impact of those closers.

"If we have a multiplier that breaks that drastically impacts not only the time of that closure but then you have to wait all those weeks after it to raise that next parent stock gilt that's coming into it," Maschhoff says.

The veterinarian also points out if they choose to mix genetic sources during a break, they also need to know those new pigs' flu strains, their endemic pathogen strains or bugs that are going to come into the herd and how that may impact production.

The pork production system also has several internal data pieces they examine such as what will these new genetics do from a production standpoint both on feed conversion and sow farm production.

With the recent changes in resources used for PRRS detection, the ability to detect PRRS after an elimination process, specifically with the use of processing fluids within their system, has made looking at those multiplier herds unique and different, she says.

"When you're processing fluids negative week after week after week after week that's a great test for looking at those three-to-seven-day old piglets but what about the wean pig?" Maschhoff says.

Trying to achieve a 100% population test on wean pigs is critical when looking at a multiplication herd because Maschhoff says, "we don't have in my opinion great ability to look at what's the total population of those wean pigs coming out the door as you move PRRS potentially through the farrowing house."

"When you have a multiplier style farm that's broke with PRRS, what's your threshold or risk level of those wean pigs?" Maschhoff says. "If you get 12 weeks negative processing fluids out the door, would you capture that wean gilt or are you going to be willing to take the risk on that wean gilt, that there may have still been some extremely low level of PRRS circulating in that herd?"

The Maschhoffs have had a couple of experiences within their system where they have added additional weeks post 12 to 16 weeks of negative processing fluids before they felt comfortable placing the animals back into the commercial sites.

"Because that original virus and those multipliers may still be lingering and we just can't detect it on the wean pigs yet because we don't have the technology and resources to look at 100 of those weaned pigs today with a diagnostic test like processing fluids that is easy to collect with minimal to no additional animal handling," Maschhoff says.

About the Author(s)

Ann Hess

Content Director, National Hog Farmer

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