Hog farmers’ PRRS plan may depend on neighbourhood

Hog farmers may need to consider where they’re farming when it comes time to decide how to cope with porcine reproductive and respiratory syndrome (PRRS).

Those whose barns are close to a lot of other hog farms ought to aim to stabilize their herd and realize that there will be another bout of PRRS, likely as soon as winter comes, Dr. Tim Loula of Minnesota told the annual swine seminar here recently.

Those in more isolated areas should aim for PRRS-negative status and to keep it clean, he said.

Getting PRRS cleaned out is relatively simple and straightforward, he said. Pigs that recover from a PRRS infection will have immunities, and if they’re sows or are saved as breeding gilts, they will pass those immunities to their offspring, which will be PRRS negative.

Within 200 days, the entire herd can be PRRS negative, Loula said, showing statistical results from scores of herds serviced by the nine-veterinarian clinic where he works. The success rates are 80 per cent or higher.

Neighbours should get together to launch a joint effort to achieve PRRS-negative herd status, thus eradicating PRRS from a region, he said.

He’s convinced this will eventually become the strategy to eradicate PRRS across all of North America.

Ontario has a task force working on that strategy and one region of Michigan will launch an effort this winter.

Particularly destructive

Loula called PRRS an “amazing” virus that has shown up in more than 1,000 different strains in northern Iowa and southern Minnesota.

One particularly destructive strain wiped out entire sow herds; they all aborted last winter, he said.

China lost an estimated 100 million pigs to PRRS last year and that strain has spread to Russia, he noted.

PRRS will turn up in the hog-dense areas of southern Minnesota every winter, by summer all of the herds will be PRRS negative, and then there will be another bout the next winter, he said. The harder the winter, the heavier the losses, he added.

Biosecurity is important, he said, noting that the virus can spread on boots of people who walk in the slush from trucks. That means people need to change footwear and clothing before entering barns, and showering before and after being in those barns is also important.

Flies and mosquitoes can spread PRRS, so openings need protective screening, Loula added.

Biofilters, or hepafilters, appear to be working, he said, but they’re expensive and labour intensive. His vet clinic deals with 20 boar studs that have the filters, and none have had PRRS. This winter a trial with 90 commercial hog barns is underway “and we’ll soon know whether this works.”

Loula showed a diagram of a farm that eliminated PRRS by ensuring all of the sows farrowing had antibodies. Their offspring grew up PRRS negative and from them the farm chose gilts to raise the next generation.

When that PRRS-free generation was raised, gilts were chosen to go back into the original barn which had been depopulated, cleaned and disinfected.

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