Better Pork - June 2007

OSHAB PRRS Survival Series - Update 1:

Bad news for one producer, but better results for two

Our April issue featured three producers who were fighting the scourge of PRRS. Two months later, the Jantzis of Millbank are still struggling to make headway against the disease. The remaining two have better results to report

by KATE PROCTER

Gerald and Donna Jantzi, Geradon Farms, near Millbank

Recap: Gerald and Donna had two 1,450-sow units, at Burnside and Geradon. Altogether, they had 11,000 nursery spaces in four locations and 20,000 finishing spaces in 10 locations. Their PRRS outbreak started Nov. 28, 2005 at Burnside. And they had their virus-negative piglets out of the nursery by June 15, 2005. Their goal: PRRS virus eradication.

Update: Unfortunately, the Jantzis’ operation is not a good news story now. “We’re kind of in dire straits,” says Jantzi, despite all the hard work in both units by the staff and managers – Ezra Keupfer at Geradon and Randy Gray at Burnside. 

Since the story in our April issue, Burnside has had clinical PRRS signs again and it is the same virus as the unit broke with in 2005. Geradon, which had had no evidence of PRRS in ten years, was also diagnosed PRRS positive on Feb. 16 of this year, but with an entirely different strain than the one that hit the Burnside unit. 

The Geradon unit had three abortions, starting on Feb. 5, and a total of 98 abortions in all.  “It was a classic PRRS break,” says herd veterinarian Dr. Doug MacDougald. They blood-tested the animals, did a PCR test, identified and sequenced the virus. They started doing serum injection on March 13, injecting gilts and sows that were in early gestation. The remaining sows were injected on March 17 and there was not much clinical reaction from any of the animals, other than a slight reduction in feed intake. 

The sows had 550 grams of chlortetracycline per tonne added to the feed until clinical signs stopped. This treatment deals with secondary infections as the herd fights the PRRS virus. They also put tetracycline in the water from Feb. 6 to 12, followed by aspirin and bicarbonate of soda in the water from Feb. 14 until March 24. As well, they filled the Gilt Development Unit (GDU), serum-injected the gilts and closed the barn. 

They have no idea how the virus got into this unit, but have completed a PRRS Risk Assessment, a new tool that the OPIC Swine Health Advisory Board (OSHAB) is bringing to Ontario. Results from this assessment will appear in the next update for Gerald’s Barn.

The PRRS break at the Geradon unit has cost Jantzi $57,646 in lost production so far. His target number of weaned pigs is 5,280 over eight weeks. For the period affected, he only weaned 3,763, a difference of 1,517 pigs, which were valued at $38 per pig. For the full quarter after the break, he is projecting a total production loss of $94,392. These figures do not include medication or increased labour costs.

Starting at the end of August until Nov. 10, 2006, the Burnside unit had an abortion rate of about six per cent, which was more than they thought they should have. They blood-tested the sows, but could not find any positive test results. Around March 20, 2007, they started having more abortions and piglet quality began to look bad. During routine monitoring of the pigs coming out of the nursery, they drew blood and found the piglets were PRRS-positive and the virus was 99 per cent the same as the virus that had previously infected this herd. “We have failed to eliminate the virus with our standard procedure and at this point we don’t know why,” says MacDougald.

On March 23, they serum-injected all of the gilts and a portion of the gestating sows.  Jantzi reports that they had some more abortions – some from injected sows, some from sows that had not been injected. One week later, they vaccinated more sows, then waited another week before completing the vaccination of the herd and the nursery. “We didn’t want to upset the whole apple cart again,” says Jantzi, of the delayed approach to vaccination. Unlike the first break, they did not use Pulmotil this time around. “We didn’t think it was worth writing out the $30,000 cheque,” says Jantzi.

The second round of the same PRRS virus through this herd has had much less effect, but piglet quality has definitely gone down and they have had to destroy more low-viability piglets. “It has been even more frustrating because we thought we had it licked when we had negative pigs going through the nursery,” says Jantzi.

When Burnside broke with PRRS the first time, they repopulated their GDU with seven kilogram weaner gilts, serum-injected and blood-tested three or four weeks later and found them to be PRRS-positive, which told them that the serum injection had worked. They did not bring in any more gilts for 12 weeks. Then they brought in gilts that subsequently went positive, which told them that there were still gilts shedding enough virus in the barn to infect other animals. At this point, the entire unit was emptied and was filled with new gilts.   

After getting negative tests from both the sow herd and the nursery, they began flowing gilts from the GDU back into the sow herd. These gilts had been exposed to the virus and then Jantzi waited at least five months before going putting them into the sow herd. They were also careful to make sure there was a greater than 12-week interval between serum vaccination and bringing sero-negative gilts back into the unit. The GDU has currently been filled with a five to six month supply of gilts, which have all been serum injected.

One complicating factor is that weaned piglets from both sow units are mixed in the nurseries and did have nose-to-nose contact. Jantzi has seen a dramatic decrease in average daily gain and the mortality rate in the nurseries has jumped from about two per cent to over five per cent.

Nursery protocols have now been changed so that the groups of piglets are segregated and go to separate rooms.  However, the piglets require exposure so they can recover from the disease before they go to the finishing locations.  The hope is that a slower exposure will allow the piglets to survive.

They have tightened biosecurity, especially for transport vehicles. Each unit has its own school bus to move pigs. The buses are washed, disinfected and dried in a heated shop between every load, but both buses use the same wash area. Truckers are provided with separate clothes, boots and scrapers.

The first PRRS break at the Burnside unit resulted in a 21 per cent decrease in actual wean numbers compared to the target of 8,580 pigs. This meant a $67,700 loss to Jantzi bottom line. The second break was not as severe as the first, but still cost $29,412 in lost production.

“I don’t know if we are making any headway on this PRRS virus or not,” says Gerald. The goal remains the same – to be producing PRRS-negative pigs from both sow units and to eliminate the PRRS virus from both herds.  
 
Actions: One of the main changes Jantzi is planning to make this time around is in the GDU. Instead of running it on a continuous-flow basis after the first batch of gilts go through, like they did last time, they have shut the unit down for six months, after which they will fill it again, expose the gilts and shut it down for another six months. 

Martin and Teresa VanRaay of Dashwood
Recap: The VanRaays have a 500-head sow herd, farrow-to-finish and continuous flow, with internally generated gilts. Their PRRS outbreak hit in March 2006. Their goal: PRRS virus eradication.

Update: The VanRaays had planned to assess whether the farrowing rooms were putting out virus-negative piglets by blood testing piglets in the nursery, beginning in early February. The first two weeks went well, with negative results on all tests. The third week revealed that there were still PRRS-positive piglets in the nursery and all testing was suspended at that time. 

In spite of the fact that there is still virus active in this herd, the herd is stable and there is no clinical evidence of the virus on weaner pig quality, says herd veterinarian, Dr. Doug MacDougald. The nursery is performing at an acceptable level, with less than three per cent mortality and is sending out 30-kilogram feeder pigs after eight weeks. There is also excellent health and performance in the finishing barn. “At this point we’re relatively happy,” reports Martin.

The VanRaays continuing to vaccinate for circovirus, as the vaccine has been giving good control in their barn. They give one shot at weaning and a booster three weeks later. “PRRS does not appear to be costing nearly as much money now that circovirus is controlled,” says MacDougald. The success of circovirus vaccines has taken some of the short-term pressure off eliminating the PRRS virus, he adds.

Their goal is still to eliminate PRRS from the herd, but the timing may change from short-term to long term. MacDougald says they need to have more information and have made a decision that, for the foreseeable future, they will allow the PRRS virus to circulate within the herd.

Action:  With the decision to accept the PRRS virus within the herd, the VanRaays are determined to make sure that it does not leave their farm and contaminate other herds. One step they are taking is to tighten up the protocol surrounding entry and exit to the barn. They had the “Danish Entrance Protocol” in place, but are attempting to ensure there is strict adherence to it. 

Bill MacDougald, MacDougald Pork, near Fullarton
Recap: MacDougald has a 1,350-head sow herd, from which he sells feeder pigs. His PRRS outbreak began in November 2006. His goal was to have a PRRS- negative herd by the end of April and eradication of the PRRS virus.

Update: Bill says that the last effects of the virus have been seen in the farrowing rooms with erratic born-alive numbers and a few more mummified pigs than normal. He notes that there have been more litters with two, three or four born alive and not as many litters with 12 and 13 piglets. However, he thinks that generally the farrowing numbers are returning to normal, pre-PRRS levels. 

Breeding back sows that went through the disease has been coming along well, says Bill.  Because he and his staff went for a period of not bringing in gilts, they are facing a hole that is difficult to fill. 

There has been no bad news at MacDougald’s barn since the last edition, reports herd veterinarian Dr. Doug MacDougald. Bill MacDougald is continuing with a closed herd policy, gilt exposure and working toward PRRS virus elimination.

Bill and his vet conducted a regional investigation of three herds that are within three kilometres of Bill’s sow herd. They discovered that two of the herds, one a nursery and the other a finishing barn, were both negative for the virus. The other barn, also a finishing barn is positive, but the virus entered from the sow herd and is a completely different strain than the virus which infected Bill’s herd. They have concluded that there is no evidence of lateral introduction from neighbouring herds. 

MacDougald’s goal is still to eliminate PRRS entirely virus from the herd.

Action:  New gilts were introduced to the herd in April. BP

Illustration: Publi Griffe