PRRS elimination: a tougher battle than expected
Monday, April 2, 2012
The Stam family of Jarvis signed on for a regional PRRS elimination and control pilot project in the hope that it would help them lick the disease. And, for a while, they thought they had succeeded
by Mary Baxter
Tony Stam first encountered Porcine Reproductive and Respiratory Syndrome in 1997 when he learned that a shipment of semen contained the virus.
"We were alerted by our veterinarian that the boars had just broken with PRRS," he recalls. Some of the semen had already been used for breeding. They threw out the rest but it was too late.
As it turned out, the strain was mild. So, in consultation with their vet, Tony and his wife Vickie chose to control it by exposing all new animals on their arrival.
By 2001, the couple had expanded the operation to 550 sows, farrow-to-finish. In 2009, they sold the sow operation to Tony's nephew Kevin Stam and his wife Christina and focused on finishing the pigs it produced. Exposure remained their main method of PRRS control until 2010, when both families joined a regional PRRS elimination and control pilot project.
For the two families, the program offered new hope in tackling a debilitating disease. But, as they would find out, even with the program's help, elimination would prove far tougher than ever imagined.
The Ontario Swine Health Advisory Board to the Ontario Pork Industry Council had initiated the $300,000 project, inspired by a similar one begun in Stevens County, Minn., in 2004. Originally the Ontario project was to run from March 2010 to March 2012 and was subsequently extended to December 2012.
Among its objectives: to identify an area in which control and elimination initiatives would take place; map the incidence of PRRS; examine on-farm biosecurity protocols and offer risk assessment; improve communications and share knowledge with the whole industry; foster producer co-operation in controlling or eliminating the disease within the area; and provide expert support.
Funding comes from the Council and its industry partners, the Ontario Ministry of Agriculture, Food and Rural Affairs, the animal health lab at the University of Guelph's animal health strategic initiative and the Ontario Pork research fund. Jane Carpenter, the board's swine disease control co-ordinator, says distinct borders – two lakes, a river and an international boundary – are what made the Niagara Region a preferred choice.
They identified 76 active producers within the region. Of those, 74 agreed to join the project and, in September 2010, they began testing. "Forty-four were PRRS-negative; 30 were PRRS-positive and there were two sites that were unknown," Carpenter says.
The Stam families had expected positive test results. What surprised them, when they received the results of blood tests in the fall of 2010, was the presence of not one, but two strains.
In December, they developed a modified live vaccine and immunized the sows against the new strain. The sows' antibodies protected piglets until weaning, when they were sent to the nursery.
Preventing the spread of the virus throughout the facility, however, was impossible. Although both the farrowing and nursery areas have separate air space, they are located in one building along with the dry sow unit (also with separate air). The farrowing room is one big room; the nursery has eight rooms and 2,000 spaces; the dry sow area is divided in two. Pigs enter the nursery twice a week and shipments to Tony leave once a week.
So, with the pilot footing the bill, the Stams sat down with two veterinarians – Martin Misener, chair of the board's science and technical committee, and Brent Jones, a member of the committee's PRRS working group – and discussed elimination. They wanted to do it once and do it right, says Kevin. "We didn't want to deal with it again."
They discussed several possibilities: do nothing and continue living with the disease; depopulate; or create a farrowing break by ceasing breeding for a period of time or relocating some pregnant sows to another location. "We concluded that the farrowing break by finding an offsite barn was our choice," says Tony.
They persuaded the federal hog farm transition program to allow them to use a barn that had been retired under the program and found a farmer near Watford willing to help.
Fingers crossed
The animals were moved in the summer, when PRRS is at its least active. The sows were bred as usual and then, in mid-June 2011, shipped to Watford a month before they were due to give birth. "We were surprised that the truck ride didn't cause any problems because they were pretty pregnant," says Kevin.
It was too risky to allow the sows to return, so Kevin and Christina acquired gilts, immunized them and then bred them to fill the hole created by relocating the sows.
In the week of July 25, 2011, after the last piglets were weaned from the remaining sows, they removed 1,900 pigs to Tony and Vickie's farm to create a short space of time when there were no pigs in the nursery. The pigs ranged in age from newly weaned to ones nearly ready for transfer into finishing barns.
Rudimentary adjustments were made to accommodate the piglets. Patio stones were added underneath to create a "stepladder" to water bowls. Several times a day, the paddles on feeders intended for much larger animals were turned and the round bottom of an old feeder refilled to make sure the piglets had access to feed. Other than that, "we just put them straight on the finishing floor and crossed our fingers," Tony says.
No longer continually re-exposed to the virus, the pigs did "tremendously well," he says. They lost only 1.5 per cent of the animals. A high rate of leg injuries was expected but didn't happen, as the piglets quickly learned how to avoid the slats.
Meanwhile, back at Kevin and Christina's, cleaning with the pressure washer began once the sows were removed. They disinfected, dried, disinfected again and dried. Sows began farrowing again in August and they began shipping pigs out of the nursery in October.
Kevin and Christina's barn was tested in mid-October and mid-November, and each time the test came back negative for the virus. "We were pretty excited" with those results, Kevin says.
At the end of January, they tested again and for the first time tested Tony and Vickie's barns too. This time, results came back positive.
Because it was November when Tony shipped out the last of the PRRS-positive market hogs, they suspect the virus had lingered in the finishing barn. The virus can live very well on its own in cold weather. Kevin suspects they brought it back to their barn on the bus used to ship the weanlings. In hindsight, he says they should have done things a little differently until they determined Tony's end was clear.
The Stams want to continue to pursue eradication but have not yet decided how they're going to approach it.
Despite the disappointments, Tony and Kevin say the program offered significant benefits by helping to facilitate the use of a barn that had been retired under the hog buyout program and offering the support of the veterinarians to formulate a plan. Finding the new strain of PRRS was a huge advantage.
"If it weren't for that, we could have lived with it for a long time before we figured it out," says Kevin, adding that, because they live in an area with few other hog barns, PRRS was the last things on their minds.
Throughout the project, there have been meetings to share information with the farmers and Tony says he's seen farmers open up about their struggles with the disease by allowing their facilities and their disease status to be plotted on a map shared with researchers and the Niagara producers.
But he feels the project's goal of knowing everyone's status, improving communications and allowing individual producers whose barns tested positive for PRRS to decide whether they wanted to become negative, isn't enough. "My objective is still to have the region consider the possibility of the whole region collectively finding a way to become negative."
Leadership needed
Both Kevin and Tony are uncomfortable that the project's financing is ending so soon. "I feel that this project needs to have funding to be able to continue," says Tony. "I do not want to be left alone now so every producer is on their own to decide how they are going to do it."
One of the project's goals is to achieve sustainability in PRRS elimination and control efforts, and farmers have been provided with simple, cost-effective measures for diagnostics, says Carpenter. Yet Kevin wonders how feasible it will be to continue with efforts such as testing all animals brought into the area for the virus without the leadership of an organization such as the board.
"Somebody has almost got to take the reins, whether that be Ontario Swine Health Advisory Board or a vet or somebody . . . to call regular meetings to keep us together, because we're pretty spread out," he says. And to remind everyone about the importance of transparency within the industry if a problem occurs, he adds. "That's going to be the challenge going forward. And what do you do if somebody doesn't follow the rules?"
Earlier this year, the board launched another program that will offer the same type of support to groups of farmers throughout Ontario as given to those in the Niagara pilot. Farmers will spearhead the projects and the numbers involved in the groups will be much smaller. Those involved in the Niagara Region program won't be eligible to participate.
Both Kevin and Tony are optimistic about the new program's chances of success. The approach means that everyone involved is doing it by choice, says Tony, and there will be "a greater likelihood of successful co-operation among that group."
Kevin predicts smaller projects based on a shared mindset will be able to proceed more quickly.
"We think it will be really helpful in terms of greater sustainability by fostering this leadership in the participants," says Carpenter of the new approach. By early February, before application forms for the new project had been issued, three groups had registered interest, she says. The deadline for applications was March 15, after which applications would be evaluated.
Elimination won't always be the goal of projects that fall under the new program, she notes, pointing out that this would be unrealistic for, say, an unfiltered farm located in the middle of an area with a dense hog population. "It is the mindset change in terms of the openness, the transparency," that's an underlying goal, she says. BP