Risk Reduction Plan Stabilizes Herd Immunity

Five-year-old Pro-Net Farms Inc., a 2,400-sow, farrow-to-wean producer alliance in northern Iowa, endured a roller coaster ride of reoccurring bouts of porcine reproductive and respiratory syndrome (PRRS) for much of its early existence. That experience produced a legacy of mediocre production, high sow mortality and a demoralized staff, states Tim Klein, DVM, South Central Vet Associates, Wells,

Five-year-old Pro-Net Farms Inc., a 2,400-sow, farrow-to-wean producer alliance in northern Iowa, endured a roller coaster ride of reoccurring bouts of porcine reproductive and respiratory syndrome (PRRS) for much of its early existence.

That experience produced a legacy of mediocre production, high sow mortality and a demoralized staff, states Tim Klein, DVM, South Central Vet Associates, Wells, MN.

To conserve funds and revive production, Klein and his clinic's South Central Management Services (SCMS), along with the 10 absentee producer-owners, decided against expensive and risky depopulation-repopulation. SCMS provides management consulting services across Iowa and Minnesota.

Instead, the team chose to embark on a fairly unusual and difficult alternative on large, absentee-owned operations — setting up an internal multiplication breeding scheme. They also doubled isolation/acclimation (I/A) to four months and strengthened biosecurity.

Their plan has produced fairly solid production figures in the last 18 months, while stabilizing herd health for PRRS, says Klein. Farrowing rates are averaging 80% and pigs/mated female/year is at 20 (Figures 1-2). Pigs/farrowing crate/year has been running about 160 for over a year. Pigs born alive/litter reached a high of 10.5 early this year; pigs weaned/sow is averaging about 8.2/litter. Preweaning mortality has dropped significantly, but still hovers near the industry average of 14%.

By far the most impressive figure is the reduction in sow mortality to about 8% (Figure 3), says Klein. This has helped turn over the herd faster.

Pro-Net is a farrow-to-wean system in which the owners receive 15- to 18-day-old pigs to grow out in their own barns. All of the owners live by the Pro-Net site at Stacyville, IA, along the Minnesota-Iowa border.

Risk Reduction Plan Reviewed

The first step to achieving better production was replacement of the 60-day I/A program in the fourth quarter of 1999, relates Klein. It was a standard I/A program with mature gilts housed in an off-site facility, exposed to cull sows and fed back afterbirth and feces.

The question wasn't whether it was an effective I/A program, but whether it was long enough. It was expanded to isolate gilts from 40 lb. to adult weight — roughly four to five months.

From 2000 to early 2001, Pro-Net still suffered through periodic bouts of PRRS, resulting from its genetic supplier multi-sourcing replacement stock and forcing the farm to return periodically to 60-day isolation.

Performance rebounded by early 2001 as single sourcing of gilts returned and the farm resumed isolation of 40-lb. gilts.

Internal Multiplication

But according to Klein, it was decided the best way to maintain single sourcing of genetics was to raise gilts internally, which would also lower genetic costs. In early estimates, the new genetics can shave $1-3/pig off production costs.

With a steady supply of replacement females being produced right on the farm, isolation has actually been extended, with gilts being isolated as young as weaned pigs to ensure that all breeding animals build the same immunity, says Klein.

Gilts are initially selected as replacements at birth, with additional selection cuts made at 50 and 180 lb., adds Steve Hargis, SCMS production supervisor.

“You have to understand that an internal multiplication program means that you've got three breeding herds instead of one,” explains Hargis. One herd is the existing herd of sows (parents) that makes terminal pigs to market. The second herd is the herd of sows (grandparents) that makes the sows that make the terminal pigs. The third herd is a very small number that are the pure lines (great-grandparents or GGPs) needed to make the grandparents (GPs).

For the new breeding program, producer-owners decided to switch genetics to what is now known as Seghersnewsham Genetics, LLC to restock the operation, says Hargis. Herd rollover is about 50% complete, to be done in the fall of 2003.

The farm will produce 1,440 replacement females each year. About 65% of the parents will be replaced annually, along with 100% of the GGPs and 80% of the GPs.

Klein and Hargis stress there is a lot at stake in keeping track of all three herds. Hargis helps the farm with detailed recordkeeping and identification, with the goal of having an on-farm system that assures the staff person with the least experience can always breed the right sow with the right semen. All replacement females are tagged in each ear in case one tag gets lost. Hargis devised a unique color code identification system for breeding that matches dyed semen and colored ear tags of females. The dyed, PRRS-negative semen is provided by Genes Diffusion, a Seghersnewsham boar stud in Wisconsin.

For identification at Pro-Net, a pink tag represents GGPs; a blue tag, GPs; a green tag, original Seghersnewsham parent stock; and red tags, GGPs selected for grandparent replacements.

For mating of the GGPs, the 12-13% of the total sow herd (nucleus) bred to produce only twice a year, staff added another layer of assurance. They put Sprayola paint on the backs of the animals that correspond with the color of semen and ear tags, points out Hargis.

Klein and Hargis have seen that the identification plan makes this breeding program practically fool-proof, ensuring accurate breeding, even on weekends.

There is a safety check for the breeding system, says Hargis. For the parent lines that are made from the GPs (blue ear tags and blue dyed semen), matings are done every four weeks. “The week after the matings are supposed to happen, I run a PigCHAMP report that breaks down the breeding schedule. It enables me to ensure that the right sows got bred to the right semen. If there was a mistake where we didn't get enough females bred, or we bred the wrong match, I've got a seven-day window where I can correct it,” he says.

Producing 25 gilts a week provides a steady flow of replacements to meet breeding targets, while providing ample opportunity to make voluntary culls, states Hargis. That has helped reduce sow mortality over time.

At SCMS's request, Seghersnewsham Genetics staff have conducted periodic audits to ensure the internal multiplication breeding program is on track. Comments have been very positive, says Hargis.

PRRS Vaccination

For two years now, a modified live virus PRRS vaccine has been used. Replacement gilts are vaccinated twice, once in the grower and again in the finisher two to four weeks prior to entry into the sow farm. Every 13 to 14 weeks, all sows on the farm are revaccinated for PRRS, he says.

“The whole goal is to have a continuous, similar level of immunity to at least one PRRS virus — the one in the vaccine — with the hope that if we can get this immunity across the whole sow herd internally, we can get whatever benefit of cross-strain immunity there is when a new strain makes its way into the operation,” suggests Klein.

“There aren't any guarantees that gilts won't get PRRS,” says Glen Zubrod, producer-owner and president of the board. “But at least now our gilts will be acclimated to whatever we have.”

To prevent transfer of the PRRS virus by needles (cited in recent University of Minnesota research by Scott Dee, DVM), needles are changed after each sow injection and also after each litter is vaccinated, notes Klein.

“We are trying to immediately apply proven scientific research, in this case that needles are implicated in the spread of the PRRS virus.

“Again, PRRS reduction is a multi-piece puzzle, and we feel that avoiding needle transfer is a piece worth addressing, and it has worked very successfully,” he says.


With PRRS circulating in the area, biosecurity at Pro-Net is very tight. Farm traffic is virtually limited to employees, the veterinarian and the owners. Visitors must be approved by the unit manager, SCMS or the producer board.

A key biosecurity barrier is a large floor mat in the office hallway which separates the “dirty” area from the “clean” entry area to the showers. Outside shoes must be placed in a shoebox before stepping onto the floor mat on the way to the showers. The goal is to reduce debris being carried into the showers from “dirty” areas.

The farm has six shower-in, shower-out stalls for employees. A seventh shower stall has been converted into a sprayer system for use as a disinfectant chamber. Based on another recent University of Minnesota study that suggests the PRRS virus may be carried on objects, the exterior surfaces of all packages that come into the farm are thoroughly disinfected. Scott Dee's Minn-esota research suggests the bottom of the package that comes into contact with floors or other surfaces is especially at risk for contamination, comments Klein.

Disease Symptoms Reduced

Hargis says the use of a number of management tools at Pro-Net has led to successful control of PRRS. The virus has not been detected in the operation, based on Klein's periodic testing of a representative sample of nursery pigs and testing of the sow herd 4-6 times a year.

Secondary diseases have also been reduced, says farm manager Harry Wallem. Haemophilus parasuis, Pas-teurella multocida and Mycoplasmal pneumonia are all much less of a problem.

Some E. coli scours occurred in baby pigs early in 2001 after the change in genetics. Regular feedback of farrowing house manure to sows before farrowing has effectively reduced the problem, says Klein. Feedback should occur at three and five weeks pre-farrowing, fed for three days consecutively.


Despite all the effort that has been expended to control PRRS, veterinarian Klein remains a realist. He believes it is only a matter of time before another strain of the virus comes calling on Pro-Net's PRRS-positive herd. He just hopes that when it does, all the programs that have been developed are enough to keep it at bay.

That outcome will ultimately be decided by staff, which so far has admirably met the challenge, agree Hargis and Klein.

Farm manager Wallem says workers remember all too well the production shortfalls, missed bonuses and the sharp blows to morale caused by repeated breaks with PRRS. He is confident staff will take the steps needed to avoid a return to the past.