We continue to learn more about PRRS virus.
While porcine circovirus-associated disease (PCVAD) steals some of the limelight at swine veterinary meetings and in monthly hog publications, let there be no doubt that porcine reproductive and respiratory syndrome (PRRS) virus is still the number one challenge around which the majority of our prevention, management and biosecurity strategies are built.
Striving to Prevent Reintroductions
Our industry is in the process of trying to develop “area” or “regional” plans to eliminate this virus, since it has proven extremely difficult to prevent costly reintroductions of the disease.
We continue to learn more about PRRS virus transmission and have improved our ability to detect its presence through a variety of testing methods. Biosecurity measures have achieved new levels following research on disinfectants, “trailer baking” and transmission.
And more research continues to be promoted and funded through multiple organizations and industry groups.
Keeping all this in mind, the PRRS virus continues to stay one step ahead of us in many instances.
While the task won't be easy, I encourage everyone to promote efforts towards eliminating PRRS virus from our industry.
Case Study No. 1
A 2,000-sow, farrow-to-finish farm had been dealing with PRRS in nursery/grow-finish for several years. Grow-finish performance, average daily gain and feed efficiency had been subpar. Mortality was continuously above target and veterinary medicine costs were higher than target levels.
The facilities consisted of multiple sites, with the sow herd, nursery and finishers separated. By adding isolation/acclimation facilities and extending acclimation time, the farm developed a stable sow herd. For several months, the sow herd was able to produce negative pigs at weaning.
Intense diagnostic monitoring of adult and preweaned piglets was performed to verify consistent production of negative pigs.
In 2004, a rolling depopulation and repopulation were performed, in which all nursery and finishing facilities were emptied and refilled with PRRS-negative pigs. At one point, the entire farm was believed to be PRRS-negative.
However, after approximately six months, the farm broke again with PRRS in grow-finish with the resident strain of PRRS virus. Investigation led us to believe that internal trucks and trailers were the most likely culprits for reintroduction of the virus.
A new truck wash and additional trailers were purchased in 2005, and a rolling depopulation and repopulation again performed. The sow herd remained stable and produced negative pigs. Employees at this site were actively involved in biosecurity protocols, and were very adept at revealing areas of potential breakdown.
The unit has marketed PRRS-negative pigs for the past six months. Average daily gain, feed efficiencies, mortality, culls and veterinary medical costs have all improved.
Case Study No. 2
A 1,500-sow, farrow-to-wean production system expanded to 2,400 sows. The sow farm was PRRS-positive, but stable, and had been utilizing a commercial PRRS vaccine for the past three years in the sow herd.
During expansion, the contract gilt supplier switched sources of replacements and inadvertently brought a new PRRS virus onto the farm.
In November 2005, over 200 abortions were recorded, and the vast majority of live piglets were very poor quality. While the abortions peaked at 30 in one day, they continued sporadically for 45 days. It was apparent the herd did not get consistent exposure throughout sows and gilts.
Live virus inoculation was performed in March 2006 by mass-vaccination of the entire herd within 10 days. Another small blip of abortions occurred, but by 14 days post-vaccination, abortions had essentially ceased.
The farm will stay with the present gilt supplier. Additional off-site isolation/acclimation facilities are now being used to provide an extended “cool-down” period. Truck and trailer procedures are being reviewed and modified. The gilt supplier is now performing more extensive PRRS monitoring.
Our current goal is to attain positive but PRRS-stable status of the sow herd, producing negative weaner pigs. Ultimately, we would like to take this herd PRRS negative.
These two cases illustrate the need for the industry to push for regional and continental elimination or eradication of the PRRS virus.
With diligence, persistence and a concerted effort throughout, I believe we can ultimately win this battle.