In an attempt to thwart PRRS breaks, Iowa Select Farms has started an aggressive adaptation of existing facilities and new construction to utilize positive pressure ventilation and filtration technology.

September 1, 2017

19 Min Read
Positive pressure filtration promises better pig health
Iowa Select Farms’ ventilation and filtration team — (left to right) Zach Schumacher, John Stinn, Jeremy Andersen and John Putney — inspects each of the system’s farms to make sure the filtration is ready to protect pigs. The team is in the cool cell room of the Saratoga gilt development unit, standing between the cool cell (right) and the wall of prefilters (left). Another team member, Ben Smith, is not pictured.National Hog Farmer/Kevin Schulz

Disease breaks can be time-consuming, costly and demoralizing to personnel on hog farms. Iowa Select Farms, based in Iowa Falls, Iowa, has lived through the toll that porcine reproductive and respiratory syndrome was taking on the company’s nearly 700 swine farms across Iowa, each year seeing farms break with PRRS.

A recent report by Derald Holtkamp, Iowa State University associate professor in Veterinary Diagnostic and Production Animal Medicine, finds that annual productivity losses to PRRS for U.S. hog producers were pegged at $580.62 million as of last October. Though that amount had fallen by some $83 million since October 2010 that is still a substantial loss for the industry.

In an attempt to thwart PRRS breaks, Iowa Select Farms has started an aggressive adaptation of existing facilities and new construction to utilize positive pressure ventilation and filtration technology to provide clean, filtered air while keeping the bad air (and airborne pathogens) out of their production facilities.

Though Pete Thomas, ISF director of health services, has only been with the company for about 1 ½ years, after spending time in private veterinary practice and with Smithfield Foods, he is being baptized by fire in the world of positive pressure filtration.

“Prior to my getting here they had already made the commitment to putting positive filtration into certain farms, and some had started the remodel of the first farms before I got here,” he says, with the first remodel barns done about two months after his arrival. New construction projects began after his arrival, and today remodels and new construction carry on simultaneously.

As the name implies, the majority of Iowa Select Farms’ setups are in Iowa, and most of those are located in hog-dense areas of the state. “It can be tough to maintain high-health herds when you have sows in Iowa, just because of the sheer volume of pigs in the Midwest,” he says. “I’ve experienced the challenges that producers have gone through to try to keep PRRS out of their herds.” He admits ISF’s commitment to high herd health in a hog-dense area was part of the draw to lure him to work for the Iowa Falls-based company.

John Stinn, environmental projects manager, heads ISF’s team of five to make sure the company’s boar studs, sow farms and gilt development units with the positive ventilation and filtration are operating as they should. In addition to making sure the systems are working appropriately and effectively in the existing barns, Stinn, Zach Schumacher, John Putney, Jeremy Andersen and Ben Smith also have the task of making sure the company’s remodels and new construction are being done to the high standards necessary for filtration.

ISF’s aggressive approach to tackling the PRRS, and other airborne pathogens, issue includes 18 remodeled sow farms and two newly constructed sow farms within the last year and a half. One of the latest constructions, the Saratoga GDU by Lime Springs in northeastern Iowa was loaded with gilts in mid-August. A week prior, Stinn and his team were on site making sure the construction crews had done their jobs. No detail is too small for his team to overlook.

As the name implies, positive ventilation/filtration is all about proper ventilation, but also effective filtration. The Saratoga GDU is surrounded by corn fields on a gravel road. Though Stinn says dust abatement measures will be taken on the gravel road, the environment is ripe with other “trash” that will hopefully stay out of the barn. The south side of each of the two barns on the site have a cool cell room, a wall of pleated cardboard filters with bird netting on the exterior to keep birds, cornstalks “and other bigger things flying through the air before they get to the filters,” Stinn says. The cool cell main purpose is to cool the air coming into the barn. The cool cell cardboard pads are said to have at least three years of lifespan, most of that dictated by the quality of the water running over them.

About eight feet in from the cool cell is a filter wall, first with 2-inch thick 20-inch by 20-inch prefilters, much like home furnace filters, that have a Minimum Efficiency Reporting Value rating of 8. Particles that get through the cool cell filter will hopefully get caught in the prefilter. “I guarantee we will get a call from barn staff in a month telling us the prefilters are dirty and need to be replaced, because they’ll go from white to brown, but they’re not dirty … yet,” Stinn says. “These can look pretty darn horrible and still be efficient on airflow.”

In the relative short time ISF has dabbled with positive filtration, they have investigated three or four filter companies prior to deciding on AAF Flanders from Louisville, Ky.

“We brought them into the agriculture market,” Stinn says, and the company has had to learn along the way, just as the ISF crew has. As hog producers know, the barn environment may not be the most conducive for equipment longevity. “About as close as what they can compare this to is a turbine generator on an oil rig.”

Schumacher says, “They have been really good at working with us; we have given them feedback and they’ve modified things for us. We generate a lot of good information for the filter companies.”

Schumacher says these prefilters actually get better with age: “as they collect more particles, more particles attach to the previous particles.” Though they get better with age, the prefilters will need to be replaced after about a year, with a lot depending on the outside environment.

Prefilters are just that, filters that catch larger particles so that they do not reach the V-bank filters that have a MERV rating of 15, similar to those used in hospitals. Each prefilter is in the same frame as a V-bank filter. The V-bank form is used because the higher the MERV rating, such as a 15, the more restrictive the air flow. “So you need to increase surface area as much as possible to be able to pull air through,” Stinn says.

High efficiency particulate air, or HEPA, filters are commonly used in medical facilities, and are rated to remove about 99.99% of particulates, and for the most part are overkill for installation in a hog barn. Stinn says ISF does use HEPA filters in one boar stud, due to the site’s location along Interstate 35 and the heavy traffic load of trucks passing by carrying who knows what? MERV 15 filters remove above 95% of particles.

“In the end, filtration is all just an odds game,” Stinn says. “You’re stopping >95% of the particles, but that small percentage that gets through, is that the one that can do some harm and does it land somewhere that a pig can get it?” Stinn says. “No filtration is perfect.”

Schumacher says the PRRS particle is about 0.05 microns, but the virus attaches itself to a larger particle to get transported around the countryside and into unsuspecting barns. “Of course you don’t know if that virus particle is viable” to infect the herd, he says.

Prefilters will be checked monthly, while the cool cell room will be checked daily during the summer to ensure everything is working properly. Prefilters and V-banks will be tested annually for airflow and resistance to airflow.

These V-bank filters will likely need to be replaced every three to four years. The ISF team relies on experience from other systems as to this timetable since the oldest positive-filtered ISF farm is only 18 months. Schumacher says it costs about $100 to replace each filter hole — one prefilter and one V-bank filter. In the Saratoga GDU, which is “small” by ISF standards has about 1,600 each of the prefilters and V-filters in the barns, as where a larger ISF barn may have 5,000 of each type of filter.

The cool cell room and the filter wall as described on the south side of the Saratoga GDU are replicated on the barns’ north side as well.

In an effort to keep the bad air out, and with air tightness being critical in a positive ventilation system, the filter wall and cool cell room are spray foamed to block any possible air leaks. Prior to any of the remodels or new construction barns accepting pigs, Stinn and his team will conduct thorough inspections of the entire site. “After having some 50,000 filters installed, we’ve seen everything that can go wrong with installation,” Schumacher says, not condemning the installation crews, just knowing that there are a lot of details that need to be considered.

“Until you get into this, you do not understand how meticulous this can be,” Thomas says.

Saratoga has nine high-performance fans located at the attic level on the south side of the barn and 11 on the barn’s north side. “Fans are the key to how this works,” Stinn says. “We are always pushing air out, never a time when air isn’t being pushed out. At least one fan will be running at all times. The fans work off of pressure, not temperature.”

Filtration not the cure-all
As the head of ISF herd health, Thomas realizes the benefits of the best filtration system can be for naught if there are breakdowns elsewhere in the system. “There has been a lot of research as to how PRRS and other pathogens can get into a herd,” he says, “from replacement animals, supplies, transportation, manure, rendering, rodents, people, fomites. There are a lot of different routes that PRRS can enter a farm and air is just one of those.”

In addition to the conversion to positive-ventilation/filter systems, the ISF new construction and remodels are also incorporating gestation pens in the gilt development units and sow farms, so farm employees are having a lot thrown at them at once, but Thomas is confident that employees are dedicated to the overall mission toward a healthy herd. “They’re trying to get a drink out of a fire hose,” he says of the amount of information farm managers and their staffs are trying to absorb. “We need to follow-up and continue to help and support them and give them feedback to improve biosecurity measures.”

Thomas spends about 50% of his time in the barns, working with staff to help them with the transition, especially early on. “First month is tough,” he says. “The people want to get it, and they want to do it right. Training alongside them is beneficial, rather than just giving them a piece of paper and expect them to get it. … Obviously a big focus to make sure we get off to a good start. Getting a relationship with farm managers and getting their feedback, they’re the boots on the ground. Those guys have learned more about the ventilation system and additional biosecurity processes and learned what makes that successful. Feedback is extremely valuable.”

He also realizes that achieving perfection in every step of a biosecurity program is wishful thinking, so ISF has employed a double-safety mechanism wherever risk of disease entry may occur. These include Danish entry and shower; double bagging lunch and then an ultra violet chamber for the inner lunch bag; mortality removal through a transition room; all weaned and culled animals through a load-out room and onto the trailer. That room is then disinfected. Anytime an outside door on a room is opened, that room is then disinfected to make sure nothing harmful gets carried in.

The Saratoga GDU is equipped with a red light on the “dirty side” to alert barn staff that it is not safe to enter a secure room until the light is turned off, such as when animals are moving through the loadout room, or when mortalities are being removed. The disinfection and drying room, where supplies are received, is also equipped with a red light.

Another example of double protection is when a barn staff member removes a dead animal, that person is then done for the day rather than risking bringing some virus back in. “We encourage them to save the dead removal for the end of the day,” Stinn says. ISF has begun installing on-site compost facilities on new facilities, as opposed to incineration or having a rendering service come on site to remove mortalities.

“Not all of our disease introduction is due to air filtration so we need to make sure that we’ve reduced the risk on everything else,” Thomas says. Risk of air transmission of diseases is a lot higher in hog-dense areas such as Iowa as compared to other locales where hog production is not as prevalent.

“We know that you won’t automatically have disease-free herds just by putting in this filtration system,” he acknowledges, “but giving the employees all the tools that they need will help us get there, and train them to be successful.”

“We’re committed to changing our approach to PRRS elimination and creating healthier herds, and making our production system better. We know we’re biting off a lot and have a big commitment, but everyone here realizes that we’re really just over a year of our first remodel.”

ISF leadership has set the bar pretty high to be successful, Thomas says, and the barn staffs have been given the tools to do just that. “PRRS has been something holding them back to achieve the top production. There’s a lot of enthusiasm and a lot of momentum by everyone in the organization and people on the farms have done a tremendous job of taking that and running with it. There’s a lot of buy-in and self-accountability to make sure things are done right, everyone has gone through the frustrations and heartbreak of a disease outbreak, so they understand what needs to be done and they understand that we cannot rely solely on air-filtration if we want to be successful. They see all the other tools we’ve given them, whether it’s the UV chamber for lunch entries, the D&D room for supplies, bench entry, transition areas for dead removal, wean pig and cull loadouts.”

Video surveillance has been installed in high-risk areas on sites, so that managers can use the captured video as training tools. “We’ve found the vast majority of everything is done right, and we’ve found these are a good feedback mechanism,” Thomas says. “We take it to employees to tell them they’re doing a good job. When there have been issues, it’s not something being done in a malicious manner, but more of a miscommunication. This helps managers retrain on proper biosecurity protocol.”

Thomas oversees the ISF health services team, which has been engaged in on-farm training, classroom training and follow-up. ISF’s animal well-being team also gets involved in performing site audits, “and we have seen areas where we need to do a better job of helping them (barn employees) understand.” A result of this, short (less than two minutes) videos in English and Spanish have been prepared and are available to employees on the company’s website to help retrain or reinforce proper protocol and procedures for employees.

Signs have also been installed at specific points to remind employees of proper protocol, and a monthly “best practices” notice is sent to employees as “a refresher so not to inundate them with too much information at once,” Thomas says.

Proof is in the pudding
As spelled out already, the best filtration system can remove about 98-99% particles, some of which can be harmful if they were to reach the hog population in the barn. Stack the best biosecurity protocol on top of that, and a hog unit should be clear of pathogens and having nothing but a swine herd with high health.

So, how does Iowa Select Farms perform?

“We’ve seen some victories with this system in the short amount of time with the completed positive filtration buildings,” Thomas says, admitting the 18 months with the “oldest” ISF site with positive filtration and ventilation presents a small sample size of results. ISF has tracked PRRS breaks system-wide starting in 2011, and “we’ve historically seen very little variation in the number of PRRS breaks in sow farms and GDU farms, so we know we have real consistent challenges with PRRS.”

Thomas discussed the impact of PRRS on ISF sow farms. As a system, farms that have stayed negative have a definite advantage over farms that broke with PRRS. From November to April, ISF farms that broke with PRRS showed a 3.5% pre-wean mortality impact in the first six months of a PRRS break compared to being PRRS-negative. Miscarriages during that same time tripled in a PRRS-positive farm, and pigs per sow per year were about five pigs less in the farms that broke with PRRS versus the ones that stay negative during that six-month period. Wean-to-market mortality from farms with an outbreak was more than double in a PRRS-positive environment versus a PRRS-negative site. “So we see a big production impact in the barns that stayed PRRS-negative compared to those that broke. That’s obviously what we’re trying to replicate in more of our farms by keeping more of the farms PRRS-negative,” he says.

In total, sow farms have had a combined 11 years of filtration time. Thomas admits there were new virus introductions in two of the remodeled sites, “but we believe that one of those was related to the population of the restocked herds. We had just put the last 1,200 gilts into that farm and within a week it was positive, so we’re linking the break to that population. The sequence was the same as what we knew we had had.” The second occurrence was also in a remodeled sow farm and was isolated to the process of recharging the pit with recycled water from the lagoons. Troubleshooting after the PRRS break revealed the plumbing was configured wrong in two rows of two barns.

In addition to remodels being potentially logistical difficult to pull off compared with new construction, there is also the possibility that old viruses can linger in the building itself. “We really don’t have a lot of down time between restocking,” Thomas says.

Most ISF sow farms are made up of six barns on a site, and crews remodel one barn at a time. “As we remodel the farms, we do not depopulate. “We have moved the gestating animals from one barn at a time off site and remodeled two farrowing rooms at a time.” Thomas says. The remodels include PRRS-elimination projects. “We have chosen to do a combination of herd closures with the existing herd or do a breeding project and depop on the back side, depending on the history of health and pathogens within each farm. When we did depop, the barn would be cleaned and sit empty for about a week before pregnant gilts were reintroduced.”

With the seventh filtered GDU project recently completed, Thomas says ISF has about five years’ worth of filtration data in those seven, “and we have not had break in those seven, so that feels good. We’re hopefully going to continue to get better, improve what we’re doing, get smarter and get better. That’s one of those ‘wins’ that I talk about.”

Staying diligent is imperative; especially in the hog-dense area most ISF sites are located. “We have a lot of movement in and out of GDUs every week, and they are all located within a mile or two of PRRS-positive pigs, so we know there’s a lot of risk there,” he says. All of our filtered GDUs did go through the fall and winter unscathed, when PRRS usually hits farms.

Biosecurity at home is important, but as Thomas says a lot of their sites are located among PRRS-positive herds so ISF had attempted to be proactive to helps their neighbors help themselves and the swine industry by sharing information. “We participate in regional control projects for PRRS and we do have a lot of dialog in the area.” Within the ISF system, PRRS-negative pigs are placed within a two-mile radius of ISF sow farms and GDU’s whenever possible, “and we work with others producers to do the same to help each other out. Sharing of information, successes and lessons learned with other producers in the areas of ISF farms are beneficial to all trying to raise healthy pigs. … The openness of the industry when it comes to pathogen-spread prevention is beneficial to the entire industry.”

Thomas says barn staffs across the ISF system are excited by the turnaround being seen in the battle against PRRS. “Everyone is excited about what we are doing, but we know we still have a lot to learn. We feel like we’ve had some good successes, but it’s still early in the game,” he says.

Plans are for 80% of the ISF sow farms and GDUs to be positive-filtered farms or farms located in areas with good disease history. Finishing sites will not be filtered.

Lessons learned
As with the evolution to any new system, not everything goes smoothly right out of the box, and plenty has been learned along the way. “In north central Iowa, there is a lot of wind. We’ve learned in the fall that high winds acting on the exhaust shutters can cause backdrafts, so we brainstormed to look at ways to mitigate the backdrafts with windbreaks, and we’ve also installed alarm systems in our farms to alert us when pressure drops,” Thomas says.

Stinn says he has learned, and reiterates that filter installation process is critical. “Details cannot be overlooked.”

Biosecurity has to be key, regardless what system a hog production facility employs, and Jen Sorenson, ISF communications director, says biosecurity has always been important to ISF, even prior to the porcine epidemic diarrhea virus breaks that reminded producers of the importance of biosecurity protocol.

Though the filtration system installs were driven to improve hog herd health, a nice side benefit is the work environment for the employees. Air is exchanged often in a positive pressure farm, and “that’s a big part of the training, it doesn’t feel the same. We have workers saying they’ve noticed the air is different,” Schumacher says. “It’s a lot drier air.”

Stinn has noticed a difference in allergies, “Outside my eyes are itchy, but I come in here and they are good because we’re preventing all the pollen from coming in.” Changes in temperature are also noticed. “Managers will call us and say part of the barn is a different temperature than in another part of the barn,” Stinn says. “It will be a couple degrees difference, as where with the old barn there would be a five to 10 degree difference.”

Schumacher did say about the only drawback to the positive pressure system is maintaining the barn’s temperature in the winter, but new strategies and technologies are already being implemented to address this.

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