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Articles from 2004 In June


Vaccine, Management Team Up to Wipe Out PRRS

A 1,150-sow gilt multiplier farm finally gained freedom from porcine reproductive and respiratory syndrome (PRRS) virus in 2002, after finishing a rollout of PRRS-vaccinated sows, thus completing a six-year effort to control and eradicate the virus.

Belstra Milling Company's PIC gilt multiplication farm, Iroquois Valley Swine Breeders (IVSB), achieved PRRS-naïve status using a conservative vaccination and management approach that enabled staff to finally walk the persistent virus off the single-site, farrow-to-finish operation at Fair Oaks, IN.

PRRS naïve is the ultimate health status for an animal population. It means that the group has never been exposed to the PRRS virus and there has been no detectable antibody or virus.

IVSB swine consulting veterinarian Tom Gillespie stresses that a multiplier unit that was once positive to a field and/or vaccine virus can become PRRS naïve once all exposed animals have been removed from the herd.

In contrast, PRRS-negative status means an animal is produced in a PRRS-positive system. However, virus exposure cannot be detected after maternal antibodies from the sow have waned.

What's been impressive at IVSB is that the farm has succeeded in staying PRRS naïve for nearly three years, observes Gillespie, owner of Rensselaer (IN) Swine Services.

“Vaccination ended nearly five years ago now, and Iroquois Valley has been producing negative offspring for about five years as well,” he adds.

Production Results

Production confirms what PRRS test results have indicated, according to Belstra Milling Production Strategy Coordinator Jon Hoek. Live pigs/sow/year has skyrocketed from around 22 during the time of the PRRS break in 1996 to an amazing 27.5 for 2003.

Reproductive problems have been minimal from PRRS infection a few years ago, and the operation has managed to keep the farrowing rate in the mid-to-upper 80s (Figure 1). Liveborn average is about 12.5 (Figure 2), with over an 11 weaned pig average (Figure 3). Stillborns and mummies have dropped from about 8% down to 5%. Wean-to-market losses are running at a respectable 4.5%, says Hoek.

PRRS Break

Gillespie says IVSB was in business five years when it suffered a moderate PRRS break in 1996. At that time, the gilt multiplier still mated females naturally and purchased semen from an outside source.

“We got on it pretty quickly because we are bleeding here monthly. We caught it in the finisher, identified that there was seroconversion (development of antibodies which reflect exposure to a disease pathogen) in the late nursery, and immediately started a PRRS sow vaccination program,” he explains.

Gillespie's basic PRRS control strategy is fairly straightforward. “We work to control all virus activity, monitor to ensure the sow herd is stable and that negative piglets are being weaned, and then we develop an additional strategy to handle nursery and finisher populations to achieve control or elimination.”

To work toward virus control, a PRRS vaccine was used in the sow herd from 1996 until 1999, when a formal control program, using Boehringer Ingelheim's first modified-live-virus (MLV) PRRS vaccine, began. Gillespie quickly learned that two doses of vaccine were necessary for protection. “Two doses far exceed the results with one dose; it is an amazing thing that we had to learn the hard way,” he says. Vaccination was given at 60 days of gestation and six days postfarrowing or postweaning. It was later determined that two doses approximately four weeks apart will work even better to begin control of virus activity.

In March 2000, Gillespie and Belstra Milling agreed it was time to mass-vaccinate sows. The sows were vaccinated twice, four weeks apart, “to provide stability and get everybody on the same playing field.” Sow vaccination ended permanently in June 2000.

During this process, naïve replacement gilts to be used as sentinel animals were placed directly into breeding and gestation to monitor any virus activity in the sow population, adds Gillespie.

“By June 2000, we knew we were weaning negative pigs at 19 days of age, but there was seroconversion in the late nursery. We wanted to stabilize the grow-finish portion of the site, so we closed the finishers to entry by doing a nursery depopulation,” explains Gillespie.

“We needed to create that bubble in the nurseries,” adds farm manager Kurt Nagel. Staff placed some of the 2,400 nursery pigs in the existing five finisher buildings and moved the remainder off-site.

Then, compromised, younger finishers were vaccinated twice for PRRS. The oldest were headed to market and didn't need to be vaccinated, because a 21-day withdrawal period must be observed for MLV PRRS vaccines, explains Gillespie.

Also, manager Nagel quarantined the finishers. “Even though we are single site, we tried to make the finishers as much a separate site at that point as we could. We designated people who went down that way, and they wore separate boots and coveralls and washed their hands,” he explains.

Gillespie recalls: “After the nursery depopulation of eight weeks, using unidirectional (one-way) animal flow, unvaccinated pigs flowed into finishing sites. This allowed us to keep an empty finisher between mass-vaccinated and negative pigs. We walked the vaccinated pigs off to market without contaminating the unvaccinated pigs that followed them.”

Gillespie says needles were changed with every pen in finishing. Also, the practice of moving finishing pigs between rooms to equalize size was stopped.

Other biosecurity practices are always strictly enforced, including shower-in, shower-out and rigid fly and rodent control programs. Boot dip use is enforced for entry to, and exit from, each room, and a spray hose just inside each room must be used to wash off boots to reduce the chance of disease spread, says Nagel.

Monitoring Program

Since finishers were cleaned up in 2000, there has been no recorded PRRS activity detected in any sow or pig populations at Iroquois Valley, stresses Gillespie.

Proof of that, and equally as important as the vaccine and management steps taken, is the monthly monitoring program, he emphasizes. The random sampling effort consists of blood testing 50 finishing pigs (10 pigs/barn, five barns) and 59 sows from the two breeding and gestating barns.

Rolling to Naïve Status

Vaccine virus persists in sows previously vaccinated. These sows were tested and removed, basically rolling them out of the system at the herd's 50% replacement rate, over a two-year period ending in 2002, says Belstra's Hoek. They have been replaced with non-vaccinated, naïve gilts.

Gillespie points out that it is important for a gilt supplier to produce naïve females for sale. So the thought of continuing to protect animals via vaccination became a moot issue at IVSB, which is sited in a low-dense hog area in northwestern Indiana.

However, if hog density is a big concern, and you are a commercial producer, continuing to use an MLV PRRS vaccine may be a wise choice, notes Gillespie.

“A lot of commercial units are happy to continue to vaccinate sows to control the field virus, wean negative pigs and then monitor the grow-finish population,” he concludes.

Since its discovery more than two decades ago, porcine reproductive and respiratory syndrome (PRRS) has certainly claimed the title as one of the most devastating swine diseases in U.S. history.

PRRS virus has produced catastrophic losses in all types and sizes of hog operations, confounding industry experts' attempts to control its spread. The ongoing challenge to subdue the disease has producers turning to a variety of control measures, some conventional and some controversial.

In the opening article of this series on PRRS control, an Indiana producer and his veterinarian used a conservative vaccination (modified-live-virus) and management approach to successfully walk the virus off a gilt multiplier farm.

In the second article, another Indiana producer and his veterinarian developed a five-year plan using a killed PRRS virus vaccine, moving a 600-sow gilt multiplier closer to PRRS eradication.

A trio of veterinarians in southern Minnesota discuss their experiences with serum therapy, a controversial, new approach to PRRS control.

Finally, a Kansas swine veterinarian has devised a closed herd procedure to phase out PRRS, emphasizing the development of natural immunity following infection, and forgoing the use of vaccines and medications.

Farrowing House Management

Since porcine reproductive and respiratory syndrome (PRRS) was tamed at Iroquois Valley Swine Breeders (IVSB) a few years back, farrowing house management has optimized output, says Jon Hoek, Production Strategy coordinator, Belstra Milling Company, Inc., DeMotte, IN.

At the center of that management strategy is colostrum consumption. “When you have a 12.5-pig born alive average, you are not going to wean all of those pigs, so we have ways of moving pigs around and saving piglets,” he says. Results have been encouraging: The weaning average is over 11, and in the last two years alone, preweaning mortality has dropped from 16% to 10-12%.

An overriding theme is the 95% “litter disruptive rate,” says Hoek. That means that 95% of litters are moved from their original mother. “Who the sow is or where the pigs go is not important — the pigs just go as needed,” he explains.

Key techniques are:

  • Using pig boxes

    These plastic boxes are placed in the farrowing crate during the first 10-12 hours after birth. At IVSB, all of the newborn pigs will stay in the boxes for a couple of hours to get dry and warm. Rice hulls and the drying agent Mistral are used to get the job done. “This is standard operating procedure and works well on all our farms,” says Hoek.

    Some of the other farms in the Belstra system use the pig boxes for other purposes. One use is to place half of the bigger pigs in the pig boxes during the first 12 hours of life to allow the 2.5-lb. and smaller pigs to obtain adequate colostrum.

  • Crossfostering

    Iroquois Valley farm manager Kurt Nagel tries to limit this practice to within the same rooms of about the same age piglets. He says the best sow for compromised pigs is often in the lower parities: a smaller sow with a good reproductive history, an even underline and smaller teats that smaller pigs can suckle.

    “A lot of times, we will take five pigs starving out in one room, and six starveouts in another room, and put them on the same sow,” says Nagel. “Pigs starving out don't have to fight a healthy pig to find a nipple; they are fighting with someone their own size, and therefore have a much better chance (of survival). Lots of times, a good nursing sow will wean about all of these pigs and they will be just as healthy and the same size as their contemporaries.”

  • Split nursing

    Pulling the biggest pigs off a top-milking sow allows the bottom two-thirds of a litter to access colostrum within the first few hours after birth, which is critical to success. “This gives even the squeakers in a large litter the opportunity to survive,” says Hoek.

  • Bump nursing/bump weaning

    Healthy pig-lets are sometimes weaned early so another group of pigs can be nursed by top sows, often resulting in these sows weaning double litters.



Milk replacer and watering cups with electrolytes are also provided pigs that are falling behind the rest of the litter, says Nagel.

To achieve these results takes more manpower. Hoek says one person to 90-100 sows is the standard ratio for the Iroquois Valley farm.

But this intensive management program makes producers more money and allows them to treat pigs as individuals, he observes.

Establishing sow herd stability to major pathogens like PRRS allows sows to perform to their genetic potential, and shows what the modern sow can achieve if managed properly, remarks Gillespie.

product news

Hydraulic Coupling System

Westendorf Manufacturing introduces the Hydra-Snap, a patented, multi-unit, high-pressure coupling system that allows the connection or disconnection of all hydraulic hoses in one quick motion. Each hydraulic hose is fastened to a self-aligning plate to create a hose assembly unit. The self-aligning plate is keyed so there is no way to ever get the hydraulic hoses mixed up. To disconnect, just rotate the lever 90° to release all the hoses. To reconnect the hoses, position the self-aligning plate into Hydra-Snap, keeping the lever at 90°. Once the hose assembly engages, simply push the lever to couple all the hoses in one smooth motion. The Hydra-Snap may be purchased with a Westendorf loader.
(Circle Reply Card No. 101)

Animal Management Software

HerdStar LLC announces the release of its strategic animal management software. HerdStar GF Pro is an integrated nursery, grow-finish database program designed to meet an industry need for a streamlined, comprehensive data management and analysis system that puts pork producers in control of their data in near real-time. The new software provides producers with the opportunity to improve data collection and assimilation by downloading feed use details from commercial and on-farm mills. Carcass data from processors can be downloaded, saving time and improving data accuracy. GF Pro also offers solutions to producers looking for ways to meet process verification, traceability and other compliance issues. The software is designed using Pork Quality Assurance Level III guidelines for creating audit trails and accountability.
(Circle Reply Card No. 102)

Semen, Embryo Shipper

CryoPort Systems, Inc. announces the CryoPorter AR1000, a liquid nitrogen, (LN2) dry vapor product designed for safe, reliable shipping of animal semen and embryos, cross-country or across the world. CryoPort says the new design is a significant improvement over their earlier model because it utilizes research and development advances from the aerospace industry and new material technology. Hexagonal in shape, the exterior housing of the AR1000 is made of durable plastic. The CryoPorter AR1000's unique, tip-safe design ensures nitrogen will not be lost during shipping, regardless of how the tank is handled. With an LN2 operating hold time of up to 16 days, its nitrogen capacity can endure even long-range international shipments.
(Circle Reply Card No. 103)

Energy and Water Saver

EMA Inc. has developed the Pumpmizer, a product specifically designed to control large irrigation pumps, saving energy and water. Many irrigation pumps in the U.S. run at a constant speed by either electric motors or diesel engines. The Pumpmizer is an environmentally hardened control which saves energy and water by varying the speed of the pump. By tightly controlling the amount of water pumped, producers can avoid excessive runoff and wasted water. Replacing diesel engines with high-efficiency electric motors and controls has allowed producers, in many instances, to qualify for a number of rebate programs, both from their local power company and the USDA, in addition to reducing their overall operating costs.
(Circle Reply Card No. 104)

Electrocoated Finish

Tarter Gate Co. introduces its American Farmland and Equestrian World brands featuring an electrocoated, or “e-coat,” finish. The new product provides a high-gloss, weather-resistant finish never before available on farm equipment. Superior to powder coat and liquid paint finishes, e-coat uses a process called cathodic deposition, where positively charged paint particles are attracted to negatively charged items to be painted. The instantaneous bond provided by this immersion coating system means there are no drips or runs, and the equipment receives 100% coverage every time. By incorporating much less iron into the depositing film than traditional coatings, e-coat also offers substantially improved corrosion resistance.
(Circle Reply Card No. 105)

Utility Tractor

The MF 431, a new 44-hp economy utility tractor from Massey Ferguson, is designed to meet the full-size tractor needs of limited-acreage farmers. The 1103C-33 Perkins engine with Fastram piston design is Tier II emission-compliant and fuel-efficient. The 3-cylinder, naturally-aspirated power plant produces 44 PTO hp at 2,200 rpm and features a rock-solid 8 forward × 2 reverse transmission that efficiently transfers power to the drive wheels. The center-shift levers are placed for easy access and smooth shifting. Like all Massey Ferguson tractors, the MF 431 is equipped with the Ferguson 3-point hitch.
(Circle Reply Card No. 106)

Send product news submissions to Dale Miller, Editor (952) 851-4661; dpmiller@primediabusiness.com

Court Supports Feeding Laws

The Kansas Supreme Court upheld a lower court ruling that state law has precedence over county law in regulating confined animal feeding operations (CAFOs).

The court found that regulations proposed by the Norton County Commission conflicted with a law providing uniform, statewide CAFO rules.

The Kansas Livestock Association and three of its members brought the suit.

PRRS Control: Chasing the Elusive

Porcine reproductive and respiratory syndrome (PRRS) causes clinical disease in many pig farms. Numerous procedures are being attempted to alleviate the effects of this disease.

Case Study No. 1

An 1,800-sow, farrow-to-finish operation has one sow site, two nursery sites and six finishing sites. The farm buys PRRS-negative adult gilts every two months from a gilt multiplier and isolates them on the sow site.

The sow herd had been chronically infected with PRRS — sick sows, abortions, poor quality pigs and poor production. These episodes commonly coincided with the timing of herd additions. It was known that the herd was infected with at least one PRRS strain. But neither consistent exposure to gilt additions nor blood testing to monitor herd status was done.

Tests identified one PRRS virus strain in the sow herd, very similar to a commercial modified-live vaccine. All sows were mass-vaccinated with that vaccine. The herd was revaccinated 30 days later, and vaccination was repeated every 90 days for two years.

The gilt isolation/acclimation area was used to expose incoming gilts to the virus from the herd by feedback of lungs from affected suckling piglets. Gilts were tracked by monthly blood tests. Gilts were also vaccinated with the commercial modified-live PRRS product.

Gilts entered the breeding area once they tested negative twice at four-week intervals by polymerase chain reaction (PCR) test.

Since the herd was stabilized, it has produced PCR-negative weaned pigs. Those same pigs are also PRRS-negative by ELISA (enzyme-linked immunosorbent assay) upon leaving the nurseries.

The farm continues to receive PRRS-negative animals from its supplier, but has added isolation space, as it takes 10-12 weeks to get the animals to become PCR negative for PRRS after exposure by feedback to the farm's virus.

Internal biosecurity procedures have been intensified to reduce the risk of introducing another virus strain from the hog-dense area. The nursery and finisher sites do not share personnel nor equipment, and enhanced sanitation of transport vehicles and loading procedures has been implemented.

Case Study No. 2

A 1,200-sow, farrow-to-finish operation produces replacement gilts internally. Gilts go through contract nurseries and return to a finisher site near the sow farm to be acclimated and grown to selection weight and age.

The sow farm had periodic clinical PRRS outbreaks, but no plan for managing gilt introductions. The producer assumed that since they raised their own gilts, the health status would automatically be “equal” to the sow farm's because that's where the gilts were born. Gilts were added to the sow herd without being tested.

After a severe outbreak produced 80 abortions and 30 sow deaths, a more organized plan was developed. It appeared that gilts were PRRS negative when they entered the sow herd, but seroconverted during feedback exposure prior to farrowing. When the population of susceptible animals reached a certain level, clinical disease returned, causing virus shedding and sick pigs.

Testing identified a PRRS strain quite different from any commercial vaccine.

Due to the severity of the virus and the impact on production, it was decided to produce an autogenous PRRS vaccine. During vaccine production (8-12 weeks), the herd was purposely infected throughout using lungs from viremic pigs.

When gilts reached selection age and size, some were rechecked for virus. Groups that tested ELISA positive but PCR negative (no virus in the blood) were approved for breeding.

Weaned pigs had maternal antibodies to PRRS, but have stayed PCR-negative through all-in, all-out nurseries. Some finishers have stayed negative to market.

Conclusions

These two cases demonstrate the complexity of both production and procedures in dealing with PRRS. No two farms are alike, and the need for intense investigation and cooperation is great. Single-site farms may not have the same risks for another introduction of virus, because there are fewer people to be compromised.

Producers and their veterinarians need to:

  • Develop a reasonable method of gilt introduction.

  • Agree on a plan of action.

  • Exercise extreme diligence in implementing biosecurity procedures, including routine testing of live animals and semen supplies for PRRS and other diseases.



The risk of introducing another PRRS virus into a herd is real, as we still don't know all the ways this virus can be carried or transmitted.

Producers should visit with their veterinarian or health advisor to develop a plan for their operation that best meets their needs.

Voluntary COOL Plan Outlined

The National Pork Producers Council is part of a group of commodity organizations that released a statement outlining a plan for a voluntary country-of-origin labeling (COOL) program.

The plan calls for providing product origin information without burdening anyone with added costs, according to the group.

The plan will recognize existing labeling programs, allow flexibility, minimize recordkeeping and be cost-effective and market-driven, they say.

Checkoff Case on Supreme Court Docket

The pork checkoff program will continue to operate, and a decision about its future will be put on hold, while the U.S. Supreme Court hears an appeal of an 8th Circuit Appellate Court ruling that found the Beef Promotion and Research Act in violation of the First Amendment.

Similar to the beef checkoff challenge, a district court judge ruled in 2002 that mandatory collections of the pork checkoff violated the First Amendment rights of producers who disagreed with certain messages paid for with checkoff funds. The Sixth Circuit Court of Appeals upheld that decision in 2003, resulting in the U.S. Department of Agriculture and the Justice Department requesting that the Supreme Court hear the case.

“I'm glad this has happened. I just really felt all along that the commodity checkoff cases in question needed to go to the Supreme Court,” says Craig Christensen, Ogden, IA, pork producer and National Pork Board president.

The Supreme Court is expected to rule on the beef checkoff case by the first half of 2005. It may take a year or more to decide the pork checkoff case, he speculates.

In the meantime, Christensen wants pork producers to participate in how pork checkoff programs are run, and to help build educational programs to keep producers competitive.

“We are not going to just sit on our hands. We have some great opportunities to move protein in the food chain to meet increasing pork demand both domestically and from an export standpoint,” he emphasizes. “We need to take advantage of those opportunities, and that is what the pork checkoff is set up to do.”

Adds Illinois Pork Producers Association President Art Lehmann of Strawn, IL: “Since 1985, pork producers have relied on the pork checkoff to increase demand and expand markets for pork and to provide on-farm information. We believe that the success of the pork checkoff has been well documented.”

Producers can learn more about the pork checkoff by contacting their state office or by calling the Producer Service Center at (800) 456-7675 or visiting www.porkboard.org.

Mandatory Price Reporting

The National Pork Producers Council supports a one-year extension of the mandatory price reporting provision contained in the 1999 Livestock Mandatory Reporting Act, due to expire on Oct. 30, 2004.

“Pork producers need a transparent, accurate and timely market price reporting system in order to make knowledge-based business decisions,” says Jim Quackenbush, chairman of NPPC's Competitive Markets Mandatory Price Reporting Working Group and a Chokio, MN, pork producer.

The proposed extension would give industry stakeholders time to develop a set of plans for system improvement, says Quackenbush.

Five-Year PRRS Program Stays on Track

Owners of a 600-sow gilt multiplier placed strict limitations on their veterinarian's proposed five-year cleanup plan for PRRS. The plan, which emphasizes testing and vaccination, has kept production steady without costing much extra money.

In some ways, 1998 was a good year for the Pumphrey family and staff at Ag Production Enterprises, based in Greensburg, IN.

Sure, hog profits were nonexistent. But that made it a good time to roll over much of the old, commercial sow herd to put the finishing touches on eradication of pseudorabies (PRV). And the operation caught a break because the State of Indiana paid for all of the blood testing.

Robert Pumphrey and production manager Bill Shobe were pleased with the PRV eradication outcome, and had been successful at managing around other diseases such as Actinobacillus pleuropneumonia, salmonella and transmissible gastroenteritis (TGE).

Five-Year PRRS Plan

After all the blood test work and production hits endured with PRV, it took some strong urging from swine consulting veterinarian Matt Ackerman to convince the Pumphreys to take on another challenge — namely a five-year plan to eliminate porcine reproductive and respiratory syndrome (PRRS).

“The Pumphreys had already switched to buying PRRS-negative animals in 1998 (Newsham Genetics), and we were already using PRRS killed virus vaccine in their herds, so why not go the extra step?” asks the Greensburg, IN, swine practitioner.

Pumphrey and Shobe finally agreed to the plan, but with some restrictions. They told Ackerman: “You are welcome to eradicate PRRS here as long as it doesn't cost us anything extra, it doesn't require a lot of extra blood testing, it doesn't interfere with production, and there is no risk of total disaster!”

Ackerman smiled and agreed to all but the last requirement. He explains, “So for PRRS cleanup, the operation was already paying for monthly blood testing, since the 600-sow operation to be cleaned up is a user group gilt multiplier. We just reallocated to bleed more sows and less finishing pigs.”

Hagerstown Farm is a closed-herd gilt multiplier with PRRS-negative semen supplied by one of the Newsham AI Centers in Indiana.

“Downstream, more gilts were being bled again as they came into the commercial farm, so we had additional testing down at that end,” adds Ackerman.

To avoid interfering with production, Ackerman has followed a sow test-and-remove plan at weaning (30 head), which is much less invasive than a herd closure, depopulation-repopulation or a whole-herd test-and-remove plan. The plan also gives the Hagerstown production team the right to refuse to cull PRRS-positive animals if, for instance, 100% of the weaned sows in any given week should turn up PRRS-positive.

Farm History of PRRS

Pumphrey readily admits his restrictions on the PRRS cleanup plan have been severe.

“Part of the reason we were able to put these restrictions on Matt's (Ackerman) plan was that we weren't having a big problem with clinical signs of PRRS. We didn't want to take a big risk and screw up something that really wasn't too bad in the first place.”

Performance Monitor data recorded by PigCHAMP shows that from 1999 through 2003, the Hagerstown Farm has averaged an 85% farrowing rate, 11-plus pigs born live/litter, over 2.4 litters/mated female/year and over 21.5 pigs weaned/mated female/year.

When PRRS was first noticed in the Hagerstown operation in 1995, few reproductive problems occurred, recalls Shobe. PRRS caused a flu-like condition in finishing and later caused a myriad of problems in the continuous-flow nursery.

“At the start of the eradication project (in December 1999), the sow herd was serologically PRRS positive and a modified-live-virus (MLV) vaccine had been used for approximately one year. Due to lack of commercial MLV PRRS vaccine options, the herd transitioned to a commercial, killed PRRS vaccine” (PRRomiSe, then sold by Bayer and later by Intervet Inc.), explains Ackerman.

In January 2000, the entire sow herd was mass-vaccinated with the killed vaccine. Then for four months, all sows were double-vaccinated with killed vaccine in mid-gestation.

Currently, all gilts are double-vaccinated in isolation on arrival at about 6 months of age, then are given a second dose three weeks later, says Ackerman. Both sows and gilts still receive one dose of killed PRRS vaccine in mid-gestation.

About 50 head of female breeding stock are blood tested monthly to maintain PRV- and brucellosis-free validation.

Following vaccination in January 2000, blood testing indicated that the sow herd was fairly stable with a low prevalence of PRRS, with about 40% of the sow herd PRRS positive, says Ackerman.

Ackerman decided on a partial depopulation of the finisher to block transmission of PRRS to sows. The farm is a modified three-site operation, with 600 sows on the main farm and a second site with a 2,000-head finisher and a 1,000-head nursery about a half-mile away.

The Indiana veterinarian decided to wait a few months after the partial depopulation to do the next round of blood testing, so the finisher could be filled up again. By May 2000, positive sample-to-positive (s/p) ratios were seen in pigs 4-7 weeks of age. These s/p ratios lasted until 8-10 weeks of age, and were determined to be normal PRRS maternal antibodies.

An s/p ratio, sometimes referred to as a titer, reflects a measure of the amount of antibody in a serum sample. If the s/p ratio is 0.4 or above on any individual animal, then the herd is considered positive for the PRRS virus, he explains.

Twelve different age groups were tested in the nursery and finisher to determine their PRRS serologic status.

Producing Negative Pigs

From May 10, 2000 to the present, the gilt multiplication herd has consistently produced PRRS-negative animals from PRRS-positive sows, stresses Ackerman.

He declares: “If those animals stay negative, then you can feel pretty confident about the stability of your sow herd. This tells us that the sow herd is PRRS positive, but they are producing PRRS-negative offspring.”

Those figures contrast with data for 2000, when an estimated 40% of the herd's females were PRRS positive. The production team wasn't excited about culling large numbers of females, so positives were culled based on age at weaning and replaced with negatives, explains Ackerman. Eventually, all PRRS-positive females will be rolled out of the herd by normal attrition (50-60% annual replacement rate).

The progression of rolling in PRRS-negative animals and rolling out PRRS-positive females is dramatized when the results of Figure 1 (Dec. 31, 2000) are compared with results depicted in Figure 2 (July 1, 2003).

“We are rolling in negative animals and rolling out the positives with very little seroconversion (development of antibodies which reflect exposure to a disease pathogen),” says Ackerman. As of Sept. 1, 2003, the herd tested 95% PRRS negative.

With permission from the management team, Ackerman conducted a whole-herd bleed on Oct. 22, 2003. Out of 647 females tested, 32 came back PRRS positive, or just under 5%. These animals were retested using immunofluorescent antibody (IFA) as a confirming test; all sows tested PRRS-negative.

Pumphrey promised if around 30 head turned up positive, they could be culled, and that was done. Blood testing of nursery-to-finish animals was also repeated to confirm earlier findings that PRRS was not present in the growing pig population.

Conclusions

In January 2004, test results took a sudden turn when about 10% of random samples tested PRRS positive. Sows that came back positive were marked, and that factor will be used as culling criteria, remarks Shobe.

Ackerman believes his control program, combining testing, vaccination and proper management, still appears to have PRRS on the run.

Monthly test results through April 2004 continued to confirm there was no clinical evidence of PRRS virus. Only a small percentage of the sow herd tested positive for PRRS by ELISA (enzyme-linked immunosorbent assay) and were IFA negative.

In short, Ackerman and the Ag Production team remain optimistic that the highly unpredictable PRRS virus, if it is indeed still present in the herd, will be eliminated in another year or so.

For insurance, they agreed to vaccinate with the killed PRRS virus product for at least another year.

“Just remember that vaccines are designed to minimize clinical signs, and won't necessarily prevent seroconversion,” says Ackerman. Depopulation-repopulation is the surest way to eliminate the PRRS virus.

“But if you want to consistently produce PRRS-negative pigs, it would be my recommendation that you utilize PRRS-negative replacements, PRRS-negative semen and a killed PRRS vaccine. We are continuing to vaccinate gilts twice in isolation, and sows and gilts once in mid-gestation (or whole herd quarterly) and continuing to produce PRRS-negative offspring out of PRRS-positive sows,” comments Ackerman.

Effect of Repeated PRRS Vaccination

Many sow herds are repeatedly vaccinated for porcine reproductive and respiratory syndrome (PRRS), despite evidence that a single vaccination provides long-acting protection, says Eileen Thacker, DVM, Iowa State University immunologist.

Thacker compared immune responses to both modified-live-virus (MLV) and killed-virus (KV) PRRS vaccines in sows that had received multiple vaccinations during their lifetimes.

She found that “repeated exposure of the immune system to the same PRRS virus antigens induces limited recall responses.”

But Thacker adds that the use of both types of PRRS vaccines “appeared to enhance the immune response.

“Thus, based on the results of these preliminary studies, use of combined MLV and KV immunization strategies may be worth further consideration,” she concludes.

Welfare Rules Add Costs For Dutch Producers

Pork production in the Netherlands is about to get a lot more challenging.

Not only did the European Union (EU) come out with tough new rules aimed at improving the welfare of pigs, the Dutch government has taken the rules further, saddling farmers with extra cost and management requirements.

“When you earn enough money, rules are not a problem,” says Gerard Peters, who farms with his wife, Francien, and sons, Timo and Pim, at Reusel, the Netherlands, near the border of Belgium. The Peters family is facing new animal welfare rules that threaten to drastically increase their cost of production, yet the consumers who demanded the rules are still free to choose less expensive meat produced elsewhere.

New welfare rules, dictated by the EU, were not enough to satisfy politicians in Holland, where producers must follow even stricter regulations. Pork producers are scrambling to figure out how they can switch from individually housed animals to group housing and still survive financially.

Approximately 30% of Dutch producers currently use group housing. Given the choice, Gerard believes most would prefer to house sows individually. The increased workload of keeping bedding dry and the feeding area clean is chief among their concerns, he says.

Expansion Plan

Three years ago, the Peters had a typical Dutch farm with 140 sows and 30 milking cows. Gerard realized that both enterprises were too small to be viable, especially with the new welfare regulations looming.

Although his heart was with the cows, the family weighed the costs associated with dairy cows vs. the opportunities with sows. They decided to focus on producing pigs. The Peters generated some money by selling their dairy quota, valued at between 78¢/lb. and $1.04/lb., roughly $13,786/cow (all figures in U.S. dollars).

They took the unusual step of housing sows in large, open pens with straw. Part of the reason that they like using straw is that the manure is much more concentrated than a liquid system. Pens hold 150-200 sows, each divided with concrete barriers to partially separate the sleeping area from the eating area. Straw bedding stays in the barn for an entire year, while the eating area is scraped daily. Manure is stored outside the barn.

North American producers looking to comply with strict environmental regulations may be surprised to learn that the Peters are able to operate a 500-sow unit on 29 acres. However, with land valued at between $13,947 and $23,246/acre, owning large acreages is simply impossible for Dutch farmers.

Manure is trucked 60 to 125 miles to western and northern Holland, at a cost of $17/ton, where it is predominantly used for crops.

Manure is tested for nutrient value to help determine the cost of disposal. The nutrient content of the manure from the Peters' operation is two to three times more concentrated than with a liquid system, so removal is less expensive.

The building costs were far less for this barn than for a more conventional operation, he notes. Straw bedding helps keep the sows warm. The Peters pay about $92/ton for straw, which translates to about $23/sow/year. Natural ventilation also helps keep costs down.

The family is still building sow numbers. Gilts are 6-7 months old when they arrive. Sows are divided into two groups — younger, leaner sows in one group; older, more conditioned animals in the other. Peters says they've had limited fighting problems when mixing the animals.

A chip embedded in each sow's ear tag operates a computerized feeding system. Teaching sows to use the feeders has been their biggest challenge. “It is a big problem,” he says, while acknowledging that the temperament of individuals plays a big role in determining whether the feeding system is successful or not. Some producers have taken the system out because they cannot make it work, he adds.

Producers must be vigilant when checking the computerized records. Because sows eat the straw, there is no visible way to tell if a sow is eating her ration without checking the consumption records generated by the computer. Each sow has her own nutrition curve and is fed accordingly. More wheat and barley are being fed. Feed is priced weekly, based on input costs. His feed costs are approximately $230/sow/year.

Management Changes

The Peters have noticed some changes in production numbers with the new system. Although their number born live is larger than before, fertility problems reflect a higher number of recycles.

Artificial insemination is used exclusively. They use Dutch Pietrain semen on their largely Dutch Landrace-based sow herd.

The new welfare regulations do permit placing newly weaned sows in individual crates for two days prior to breeding and for four days after. Bred sows are moved to the main barn and placed in large groups during gestation.

Since sows have only been away from the group for four or five weeks, they remember their penmates and do not fight much, he explains.

A boar is kept in the sow barn for heat detection. Sows showing interest in the boar are taken back to the breeding barn for a second service. Eighty to 85% of the sows conceive at first breeding. Recycling sows that do not conceive in the second breeding are culled. Veterinarians perform ultrasound pregnancy checking during routine visits.

At birth, piglets' teeth and tails are clipped and they receive iron shots. Piglets are also given an injection to fight Mycoplasmal pneumonia and an oral treatment to combat coccidiosis. Males are castrated at 7 days of age.

At 8-10 days of age, the Peters remove the biggest pigs in litters that are too large and puts them in an empty farrowing pen equipped with a small wooden hutch and heat lamp. A computerized milk feeder mixes warm water with powdered milk replacer and dispenses it to the piglets every hour.

Quality Assured

The Peters farm, like 90% of Dutch farms, is enrolled in the “Integrale Keten Beheersing” program (IKB), a quality assurance program that guarantees food safety. IKB has over 400 different requirements, but Gerard says most of them are things that farmers do anyway.

IKB rules require farmers to buy feed from an approved feed company, keep a record of any farm visitors and follow strict hygiene measures, especially in transport. Farms must have truck-cleaning facilities and showers.

A veterinarian visit is required every two weeks. Some medications are not permitted at all, while others have longer withdrawal times than on farms not following IKB rules. A veterinarian must prescribe any medications used on the farm. Antibiotic use in feed is limited to very young piglets.

Gerard and Francien run the farm, with part-time help from one son. A normal day begins at 7 a.m. and evening chores usually end around 8 p.m.

They are paid $23 to $25 for each 5-week-old piglet sold, although they do not have a contract.

The Peters have changed to a three-week production cycle, allowing them to market groups of 700 piglets. These larger groups bring a slight premium.

The pigs go first to a nursery, then to a finishing barn. Holland's welfare rules state that pigs are allowed to move only once; therefore, all of the Peters' pigs are exported to Germany.

Although they receive less money per animal than they did when they were selling pigs at 50 lb., Gerard says they are further ahead because they do not have the extra cost associated with raising weaners (less medicine and feed and manure removal).

The Peters wean 23 to 24 pigs/sow/year and have about 12-13% prewean mortality, both average production numbers in Holland.

Dead stock on Dutch farms is picked up and incinerated. The Peters pay by weight for smaller animals and by the animal for larger ones. Their average monthly charge is $115.

Nuisance Protection

The Minnesota legislature passed a statute protecting agricultural operations from frivolous nuisance claims.

Operations are protected provided they are located in an agriculturally zoned area; they comply with all applicable federal, state and county rules and permits issued; and they operate according to generally accepted agricultural practices.