Better Pork - August 2007

OSHAB PRRS Survival Series - Update 2:

Our June issue told the stories of three more producers whose herds have been afflicted with PRRS. They have not yet won the battle, but all have undertaken testing or made changes with a view to returning to PRRS-negative status

Some positive results, but continued vigilance and assessment required

by KATE PROCTER

The Vanden Boogaards of Gorrie, Huron County
Recap::  Piet Vanden Boogaard’s 900-head sow herd broke with PRRS in November 2004. After the initial drop in farrowing rate and increase in pre-wean mortality, the disease did not have a huge effect in the farrowing barn, where production eventually returned to pre-PRRS levels. The Vanden Boogaard herd was affected mostly in the nursery and finishing facility, where it suffered from higher mortality rates, slower growth rates and higher cost of production, explains Dr. Greg Wideman, the herd veterinarian.

Goal: The Vanden Boogaards hope to start producing PRRS-negative piglets in order to produce PRRS-negative replacement gilts.

Update: One of the big issues on Vanden Boogaard’s operation has been the way gilts are introduced, explains Wideman. They were raised under the same roof as the commercial stock, where they would become infected with PRRS and then bring it back into the sow herd. Vanden Boogaard plans to change this and has set up a separate multiplier herd so he can start doing his own internal multiplication.

Vanden Boogaard and his family have begun testing the offspring from this multiplication unit, which have so far come back with negative results. “You have to test a huge pile of suckling pigs in order to say that you’re negative,” explains Wideman. 
Wideman plans to continue blood-testing the population of gilts until they are ready to go into the sow herd.

After the gilts leave the nursery, they will be raised in a separate rearing and acclimatization facility. They will be serum vaccinated and then blood-tested to ensure that they are not shedding virus before entering the sow herd. “We will do this until we are convinced there is no circulating virus,” explains Wideman. The plan is eventually to stop serum inoculating.
 
Action:  The Vanden Boogaards will be completing an OSHAB-sponsored PRRS risk assessment and have already made some biosecurity and management changes in order to try and control the movement of the PRRS virus on their farm. 

In the farrowing rooms, they have implemented a revised McRebel protocol – restricting fostering so that there is no piglet movement outside a 12- to 24-hour window after birth. They are not focused so much on making the litters even, but rather are trying to ensure that “every pig has a decent teat to suckle,” says Wideman. Any litter that is suspect – for example, less than six born alive, more than three still born or mummified – will have no piglets added or taken away.

They will closely monitor the newly-placed piglets in the nursery. If there are too many getting sick and dying at that stage, Wideman explains that they will make the fostering rules even stricter.

The Vanden Boogaards are also being more careful about people movement between barns. They have set out strict protocols governing which barns specific family members can work in and have also tightened up the rules about how pigs are moved between facilities.

Darryl and Cheryl Terpstra, Birchlawn Farms, near Dorking
Recap: The Terpstras have a 900-head sow herd with an on-site nursery. They have battled various disease issues over the years, but broke with PRRS again in December 2006.

Goal:  Their aim is to produce PRRS-negative pigs.

Update: Dr. Martin Misener, their herd veterinarian, reports that the intervention program at the Birchlawn herd has been very successful so far. The herd experienced a peak nursery mortality of 7.8 per cent, which has dropped back to less than three per cent. The key indicators in the farrowing barn have mostly returned to pre-PRRS levels. However, pigs weaned per sow has not come back and still sits at half a pig less than it was before this outbreak occurred (see charts above and on previous page). They have blood-tested 25-kilogram pigs and are waiting for the results.

Action:  The Terpstras are planning to complete an OSHAB-sponsored PRRS Risk Assessment and continue monitoring the 25-kilogram pigs leaving the sow nursery. They will also continue serum exposure of the gilts in the gilt acclimatization barn.

Ron and Glen Manjin, Teeswater Pork, Huron County
Recap: This father and son team were in the process of filling their 2,300-head sow unit when they received PRRS positive gilts in the final load on Nov. 17, 2006. They have brought in no new gilts since December 2006.

Goal:  To take the herd back to a negative PRRS status.

Update: Ron reports that, overall, they have been seeing positive results in this herd. Their gilts started producing their second litters on May 21 and the number of piglets born live has improved over the first parity. Their herd veterinarian, Dr. Martin Misener, says they sampled 30 piglets in March and performed polymerase chain reaction (PCR) for PRRS and found only one positive pool. “This is a good way to establish trends, but does not accurately identify viral elimination from the sow site,” he says.

Early in the PRRS outbreak, there was an interruption in gilt delivery, so they had a three-week gap in breeding at that time. This was helpful because it meant that, for three weeks, there were no piglets on inventory. As a result, Misener is very confident that they will be able to eliminate the virus from the herd.

Action: In July, the first gilts since December 2006 were brought into an on-site gilt isolation barn. They were not serum-injected, but will be entered into the herd as PRRS-negative with the goal of taking the entire herd back to a PRRS-negative status. The Manjins will set up a monitoring program, which will include testing 25-kilogram pigs at the end of the nursery phase and also testing new gilts.