Preparing for feeding sows, market pigs in winter

Thermal stress can affect swine performance at both ends of the thermometer, especially in northern climates such as Minnesota, the Dakotas and Iowa. While heat stress gets a lot of attention globally, cold stress can also be significant.

Preparing for periods of thermal stress also requires forethought and planning, so producers are prepared and know what to do or what to expect, according to Dr. Julia Holen, a nutritionist with Swine Vet Center in St. Peter, Minn.

Going into winter, adverse weather conditions can affect not only livestock, which in the case of most swine are kept indoors in climate-controlled facilities year-round, but also equipment on farm as well as the ability to access farms to deliver feed and supplies.

“We recommend producers keep an eye on the weather and try to have backup feed on hand if a snowstorm hits, especially over a weekend, in case you can’t get to the barn during the storm. It is also a good time to do maintenance checks on feed and water lines as well as ensuring ventilation systems and backup power systems are working properly,” said Holen.

More specifically related to swine nutrition, Holen provides a few tips to consider going into the fall and winter for sows and grow-finish operations.

Ensuring sow feed intake

“As new-crop corn becomes available, corn and corn-DDGS should be tested for mycotoxins to understand what may be present in your region or from nearby feed mills,” Holen said, explaining that different mycotoxins or a combination of mycotoxins can have varying effects on sow performance.

With new-crop corn entering sow rations, or really when any change is made to sow diets, Holen said it is a good time to recalibrate feeder settings within the gestation barn. She recommends checking at least 10 feed boxes for each box setting – the more the better – to ensure the sow is getting the expected quantity of feed. If the ration is formulated based on the expectation that sows are provided 4 lbs. but the feeder is actually delivering 3.5 lbs. on a true-weight basis, the sow may not be getting what she needs, Holen explained. On the other hand, if the sow is provided more feed than expected, sows can become over-conditioned during gestation.

“The volume of ingredients within diets can also affect feeder calibrations. Grain co-products such as DDGS, soy hulls, and wheat midds may have differing moisture content or volume that could impact the physical characteristics of the ration. Different batches of corn with differing test weights or moisture levels can have a similar influence on bulk density of the diet. Whenever there is a significant change to diet composition or ingredient sources, feeder boxes should be recalibrated to validate that sows receive an amount of feed that is expected based on feeder settings,” Holen said.

Grow-finish strategies

“The first thing to understand on the grow-finish side for winter feeding is if the operation is under a fixed-time or a fixed-weight marketing strategy,” Holen said, noting that the time and space available in a barn will affect pig feed intake and expected growth performance.

If a barn is long on space with no real time constraints, pigs often have more space than they need and may consume more feed than normal, she explained. Understanding the actual feed intake of growing-finishing pigs going into the winter months is key for producers to reach target market weights. In this scenario, growth rate of pigs may not be limited, however, the additional cost from higher feed intakes may not always provide a positive economic return.

If available pig space is short and time does become a limiting factor, nutritional strategies such as increasing energy concentration of the diet may support improved growth rates and fewer days to market.

Holen said it doesn’t look like inclusion of dietary fats will be economical going into this winter but including high fiber ingredients such as dried distillers grains is likely to be economical. She said when rations push into the higher inclusion levels of DDGS, however, producers need to be mindful of the potential negative impact to carcass yield and may need to consider a step-down or withdrawal period with the final finishing diet right before marketing. “While it may be least-cost to include high DDGS throughout late-finishing, it may not have the greatest benefit or margin over feed cost due to lost carcass yield and potential impact on pork fat quality. I typically recommend stepping down DDGS inclusion prior to marketing, but every producer’s economic scenario is different and must be considered.”

Regardless of season, Holen said she is frequently asked if diets should be adjusted in case of a health challenge. She noted that there is a slight increase in energy and amino acid requirements for those pigs, but it is relatively small. Often-times, the reduction in feed intake and increased protein degradation that occur for health challenged pigs can’t be compensated for through diet adjustments alone. Although we can make diet changes to try and help health-challenged groups, she said, simply getting pigs to eat can be the biggest hurdle to overcome.

Breaking down the SDRS, what it means to the swine producer

The Swine Disease Reporting System (SDRS) is a tool developed by a consortium of veterinary diagnostic laboratories in cooperation with the Swine Health Information Center to share information on endemic and emerging swine diseases so veterinarians and producers can make informed decisions on disease prevention, detection and management.

Dr. Paul Yeske with the Swine Vet Center explained that the monthly SDRS reports allow the swine industry to monitor trends and predict when herds might be at a greater risk of an outbreak.

The SDRS – led by the Iowa State University Veterinary Diagnostic Laboratory with participation from the University of Minnesota Veterinary Diagnostic Lab, the South Dakota Animal Disease Research & Diagnostic Laboratory, the Kansas State Veterinary Diagnostic Laboratory and the Ohio Animal Disease & Diagnostic Laboratory – helps veterinarians better understand the epidemiology of particular pathogens moving among swine populations, Yeske said.

For example, in the last four years, whenever there has been an increase in porcine reproductive and respiratory syndrome virus (PRRSv) activity in grow-finish units, there tends to be an increase in positive cases in sow herds a month later. So, when PRRSv activity is trending up in the grow-finish barns, nearby sow farms may want to make sure they’re doing everything possible relative to their biosecurity protocols to reduce the risk of the virus spreading into nearby sow units.

(This is the breakdown of the different phases of production showing the turn up in PRRS in wean to finish.)

SDRS also reports data on a geographic basis, so users can look at what regions are hotspots for a disease and then act accordingly to minimize pathogen spread, he added.

Yeske likes to compare the monthly SDRS report against the weekly Morrison Swine Health Monitoring Project reports because they use different approaches to examine data. “The Morrison project is based on farms reporting clinical signs they’re experiencing, while SDRS uses diagnostic data from university veterinary labs.” said Yeske. It is interesting to see it from two different perspectives can identify similar trends.

He noted that the SDRS has a bias in that it is based on diagnostic data, so the data is derived from people looking for a problem, but it is still valuable to look at as an industry because at least you know what people are out looking for and then what they’re subsequently finding when looking at a particular population.

SDRS also reports viral sequencing, so users can compare the virus strains they’re dealing with in their herd compared to what is circulating in the broader industry, Yeske said, noting that more recently, PRRSv strains 1-4-4, 1-7-4 and 1-8-4 have been the top three viruses circulating, along with the vaccine virus.

Porcine epidemic diarrhea (PED) virus, mycoplasma and influenza are also tracked by SDRS. Yeske adds, “PED incidence has been occurring more in the January time frame, so producers can be aware and start to monitor for early signs of the virus as winter approaches. Similarly, mycoplasma tends to drop off in the summer and go up in the winter, so steps can be taken to reduce the risk of mycoplasma entering a herd and hopefully head off any outbreaks before they happen.”

The SDRS predictive model is based on the three previous years with some statistical analysis, Yeske explained. In the report, for each pathogen, there’s a shaded zone where the report authors believe normal activity should be, so if the trend line jumps out above that shaded zone, there’s more activity going on, or if it drops to the underside, there’s less activity.


Yeske said the biggest surprise in the current reporting is that the swine industry has started to turn the corner on PRRSv on grow-finish operations. He said in the previous few years, PRRSv has started to increase in grow-finish in August and early September, but this year, the virus has held off until September.

For PED, he said there was more activity last winter and spring, but that went back under control over the summer, so the overall PED numbers have come down and “we’ll have to see what happens this winter.”

Long-term value

Yeske said the long-term value of reviewing  the monthly SDRS reports is the ability to get that predictive interpretation and to see what is happening across the swine industry, not just in a single herd or system. “Sometimes, it feels like you’re the only one that’s breaking (with a disease), and well, the reality is a lot of herds are breaking, so there is value in understanding what is going on with the rest of the industry,” he added.

On the SDRS website, Iowa State also has a dashboard that allows users to dial in and take a closer look at the data and proactively notice trends in a particular geography for a particular pathogen. These tools can help users maintain awareness of pathogens that are affecting their herds but may not be getting industry-wide attention.

Yeske noted that last winter, the SDRS reports showed increased activity of acute pleuropneumonia (APP), which hadn’t been seen for a while but was spreading among grow-finish operations.

There is value in accumulating diagnostic information, Yeske said, because SDRS brings together data from multiple sources and puts them in a single place where additional analytics can be applied to create better disease management tools. In the past, these data were in individual research projects or individual reports that stakeholders would need to search for, but now, with the SDRS dashboard, users can view the monthly report and get a summary of what is happening across the industry.

Deeper diagnostics

In addition to the surveillance data from PCR sampling for influenza, mycoplasma, PRRSv and PED, the SDRS reports also look at tissue cases – where the diagnostic labs do more specific tests on submitted tissue samples, Yeske said. These tests show everything that is found in a particular sample and how those relate to each other. For example, on enteric cases, is the most common pathogen rotavirus, an Escherichia coli or a clostridium? And because of the overlap many cases have, which is more dominant, and which may be secondary infections?

Typically, when a veterinarian sends in a tissue sample, he/she is trying to solve a health challenge that needs more diagnostics than ongoing monitoring may provide.

Overall, the value of tools such as the monthly SDRS report is to provide producers and veterinarians information on the disease trends occurring across the swine industry and within particular geographies so that they can make informed decisions about disease prevention and management.

Visit The SDRS website for various reports, dashboards and podcasts that summarize key content and data.

Truck wash audits, SOPs boost biosecurity

Many successful truck wash operations utilize an internal audit system where someone is responsible for monitoring processes as trucks and trailers move through the wash, according to Dr. Erin Kettelkamp with the Swine Vet Center.

What should these audits or assessments include? Kettelkamp uses an evaluation form that helps her gain a good understanding of the day-to-day practices at a truck wash. Her goal is to understand the flow of traffic throughout the day, how many trailers are getting washed each day, whose trailers are getting washed, and the logistics associated with individual truck movement. From there, she wants to understand the company’s expectations for washing standard operating procedures (SOPs) and whether the behaviors – what is actually being done in the truck wash – match the written SOPs.

“If the goal at the end of the day is to have a very clean trailer, it’s important that we’re measuring and assessing that process,” Kettelkamp said, noting that inspecting a trailer while it’s still in the wash bay helps ensure the wash crew has gotten into the hard-to-reach areas, and if necessary, allows them to rewash missed areas without having to pull a trailer back into the wash bay.

She said some of those hard-to-reach areas include the ceilings in the lower levels where there can be spray residues, along the support rails where dust can accumulate, and behind gates and hinge points. Kettelkamp said in trailers with multiple decks, the ramps don’t always get pulled out fully during the wash process so shavings and other materials may hide there and re-contaminate the trailer.

Depending on the configuration of a trailer, the nose of the trailer may have different angles and supports that a washer – normally facing the front of the trailer while washing – may miss because they may not turn around and find the non-standard hiding spots.

Kettelkamp said the focus of the wash crew should be to remove all organic material in order to implement an effective wash. “First and foremost, we have to do a really good job with the initial power wash. We can layer on all the disinfectant we want, but if we’re not getting the initial wash done right, then disinfectant and all those other steps really aren’t going to help us any,” she said.

For the disinfectant step, she said a variety of disinfectants are used throughout the swine industry, and as long as they’re verified to be efficacious against all of the major pathogens, they tend to do a good job if the trailer has been thoroughly power-washed first.

This includes the outside of the trailer, especially the wheels, wheel wells and belly of the trailer, which should all get a good full rinse. She suggested that during the winter, if the snow and slush is not getting cleaned off the outside of the trailer, and if trailers are being pulled out of wash bays that haven’t had time for the ice to melt off, the wash crew is probably not doing a very complete job.

Kettelkamp said a best practice should be to have trailers washed between each use, but from a logistics standpoint, the industry hasn’t been able to move in the direction of fully washing between every downstream trailer movement. She said a general expectation would be that trailers coming into contact with a sow farm or other high health site should be washed, cleaned and disinfected before every use.


Kettelkamp noted that there’s been some discussion about automated truck wash bays for the cleaning of feed trucks and other vehicles that may be entering pig production sites. These systems may help decontaminate wheels, wheel wells and the bellies of vehicles that do not come in direct contact with animals. The poultry industry has installed some of these automated systems, but Kettelkamp is not aware of any in use in the swine industry.

Otherwise, washing trailers is back-breaking work, especially when scraping and washing triple- or quadruple- deck trailers, so some type of automation could help in those situations.

Baked trailers

According to Kettelkamp, some swine companies have been “baking” trailers as an extra step in the process. To do so, the wash bay or other room is heated until the surface of the trailer reaches a temperature of 160°F for at least 10–15 minutes to deactivate viruses such as porcine reproductive and respiratory syndrome virus (PRRSV) and porcine epidemic disease virus (PEDV).

She noted that the process can also be effective if the trailer is heated to a lower temperature that is held for a longer duration to dry out and bake the trailer.

A full cycle time for a truck to enter a bay and heat the room long enough for the surface of the trailer to reach 160°F for 15 minutes can take more than 1 hour, depending on the external weather conditions, Kettelkamp said.

Surrounding truck wash biosecurity

Beyond looking at the cleaning practices of trucks and trailers, Kettelkamp said it is a good idea to look at the biosecurity of foot traffic and vehicle traffic around a truck wash.

Wash facilities should be set up in a linear arrangement or potentially in a circle, where dirty trucks or vehicles may enter on one side or through one driveway and nothing gets past a line until it goes through the wash and disinfection process before it can be on a designated clean side of the wash.

That way, she explained, cross traffic between vehicle employees and/or maintenance trucks on the site is minimized. There should be clear lines of demarcation of “this is dirty” versus “this is clean” and our washes should be managed that way, she said.

The site for the truck wash also should be carefully chosen so clean vehicles are parked upslope from unwashed trailers; in the case of rainfall, runoff from dirty trailers should not flow to where clean trailers are parked, exposing them to recontamination, Kettelkamp said.

“We should have the same thought processes and practices for entering a truck wash as we do for entering a sow farm. How do we minimize cross contamination within our buildings or setup and how do we keep trailers clean and minimize foot traffic in and out? What are our designated dirty areas? What are designated clean zones for foot traffic on a wash?” she said. “We know we’re dealing with a lot of fecal material, but if we’re tracking it all around the site and potentially re-contaminating other areas, including trailers that were initially clean, we’ve got to think of a better way to mitigate that risk.”

Developing truck wash SOPs, validating, and assessing how well those SOPs are employed and considering how vehicles and personnel move around a truck wash are all key aspects that will help improve site biosecurity.

Summertime coccidiosis challenges in pigs

The hot, humid days of summer often bring the challenge of coccidiosis in pre-weaned piglets in the farrowing barn, but that challenge has now become more prevalent year-round, according to Dr. Laura Bruner with the Swine Vet Center in St. Peter, Minn.

In the last couple of years, coccidiosis in young pigs has been a hot topic because the disease management tools available in the past have not been available due to supply chain issues, she added.

Typically, the classic presentation of a coccidia infection on a sow farm is a yellow and pasty diarrhea that develops around 7–14 days of age in piglets. The diarrhea is very noticeable – it’s thicker, not a watery diarrhea that would go through the flooring – and it builds up in the crate and environment, she explained.

Coccidiosis generally does not cause mortality in piglets but does cause significant loss of gain – so it wouldn’t be surprising for pigs with a heavy coccidia infection to weigh 1–2 lbs. less at weaning than uninfected pigs. “It definitely hurts the gain of the pig, and when you talk about gain in pigs, that’s everything. How fast can I get them to market?” Bruner said.

Along with coccidia challenges, secondary infections are possible because enteric cells of the gut become disrupted, which allows other enteric bacterial and viral pathogens to invade the intestinal lining. These secondary infections are more likely to cause mortality, especially if the pig becomes really chronic.

Prevention and control

It takes seven days for coccidia to mature and sporulate oocytes, which are then shed allowing infection to spread. Anti-coccidial or anti-protozoal medications such as ponazuril (trade name Marquis) have been developed for other animals such as horses and companion animals that kills coccidia at the right time in its life cycle so sporulation does not occur.

With a valid veterinarian-client-patient relationship (VCPR), veterinarians can recommend these medications for use in piglets. Oral administration of ponazuril to piglets starting on day 3 would break the sporulation cycle and eliminate coccidia from the farrowing unit environment.

However, due to supply issues, product availability is low and what is available typically goes toward horses. This has left the swine industry without many preventative tools, Bruner said.

Given that coccidia are exceptionally hardy organisms that build up in the environment, if a producer never has a way to decrease coccidia shedding or decrease the environmental load in their barns, it just continues to build up. “I think that’s part of the reason why we’ve more recently had problems in the winter, when we wouldn’t typically have them, because we haven’t been able to knock down that cycle,” Bruner added.

There are other products developed for cattle and poultry species that have been tried under the VCPR provisions that allow the use of medications off-label, but those products are not coccidiacidal – so they don’t kill the coccidia – but are coccidiostatic, meaning they inhibit coccidia’s life cycle but don’t eliminate it.

Generally, coccidiostats need to be fed continuously to keep the coccidia at bay so disease can be prevented until the pigs are weaned off the farm. Bruner added that this option is labor intensive and not that effective, since the piglets really need to consume the coccidiostat for the entire period they’re in the farrowing unit, meaning the return on investment for this practice is not good.

By providing a coccidiostat, Bruner said clinically, the disease effects get better but the coccidia are not gone. “I think all it’s really doing is decreasing the environmental load to give you a chance to sanitize your way out of it,” she said, leaving the industry kind of stuck between a rock and a hard place.


To sanitize against coccidia, historically, producers would use a very strong bleach or ammonia solution when cleaning a farrowing room between groups, but those solutions can create human safety concerns.

Instead, producers have moved to whitewashing – spraying hydrated lime and coating the crates and all of the contact areas that piglets would touch – to try to eliminate coccidia with a really high pH solution.

Bruner said whitewashing has been fairly effective, but the right amount of hydrated lime needs to be applied in a thick coating on all contact surfaces for it to work well.

With coccidia challenges extending throughout the year, producers may have to start applying whitewash earlier in the year, such as in March or April, and not wait until June or July when it gets hot and there already are coccidia problems, Bruner said.

Another key step, Bruner said, is to routinely inspect sanitization efforts – after sanitizing the room, ask “how good of a job did I do?” and then after the room is sprayed with whitewash, ask again, “how good of a job did I do?” Inspect what you would expect to see and how well you covered contact surfaces.


After weaning, coccidia is less of a problem, but if secondary infections were present in the farrowing crate, there can be lingering effects in addition to other post-weaning stresses.

There is a portion of the population that doesn’t recover from a coccidia infection, but for the most part, it is mostly a weight-loss issue, depending on how fast the pig’s intestinal tract can heal. Any post-weaning infections with rotavirus or E. coli will just add fuel to the fire of health challenges.

According to Bruner, the key to managing coccidiosis is knowing when it will be at its peak and getting ahead of environmental contamination. Coccidia enter the farrowing house from animals – typically from gilts that may be shedding – so in theory, batch systems would have fewer issues.

Once coccidia gets into a farrowing house, it is hard to get out, but staying on top of sanitization practices and inspecting procedures to ensure full coverage will help minimize any health and performance challenges.

APP focuses attention on finisher unit biosecurity

While biosecurity remains the best option for managing Actinobacillus pleuropneumoniae (APP) outbreaks in swine finishing barns, the recent APP outbreaks in the Midwest has spotlighted biosecurity gaps in this phase of production, according to Swine Vet Center veterinarian Dr. Ethan Spronk.

APP is a gram-negative bacteria that requires swine as its host. There are 15 known serotypes, with serotypes 1, 3, 5 and 7 the most common, Spronk said, noting that serotype 15 is a newer strain currently challenging the industry.

Clinical signs of APP include sudden death in finishing hogs, especially in the mid-weight to early marketing periods, with occasionally bloody discharge from the nose. Prior to death, pigs experience respiratory distress, open-mouth breathing or gasping for air. On necropsy, lungs are found with dark purple abscesses with adhesions. Death is often caused by cyanosis – decreased oxygen supply to tissues – from the adhesions and abscesses in the lungs, Spronk noted.

APP develops very quickly once it starts, he said, and it is usually set off by a stress event – poor ventilation, high outside temperatures, other viral or secondary challenges or outbreaks, as well as sorting and/or loading for marketing purposes.

APP is spread on fomites, such as all the equipment – i.e., boots, coveralls, sorting panels, shockers, etc. –used for sorting/loading or mortality removal, he said.

Treatment of APP is a whole-herd or pen antibiotic injection, Spronk said, noting that products that have been the most successful include enrofloxacin (Baytril® or Enroflox®), tulathromycin (Draxxin®) and ceftiofur (Exenel®/Naxcel®). See product labels for use directions, etc.

There are also autogenous vaccines that offer cross protection among APP strains, he noted.

Biosecurity protocols

The recent APP outbreak is focusing attention on finishing unit biosecurity, Spronk said, explaining that due to porcine reproductive and respiratory syndrome (PRRS) and porcine epidemic diarrhea, a high degree of attention has more typically been placed on sow farm biosecurity, but finishing barn biosecurity practices haven’t gotten the same attention until now.

At least nine central Iowa pork production systems have been affected, but there doesn’t appear to be a common link among the systems. Iowa State University has been diligently seeking to better understand the epidemiology of the current outbreak as it seems to be moving differently through pork flows compared to prior outbreaks with more lateral breaks versus the usual sow farm flow outbreaks.

One concern identified in Iowa, Spronk said, was the presence of rendering trucks on affected premises, or epidemiological links were identified to positive sites that did have rendering trucks, a common service provider or marketing crew.

These findings highlight the need for good biosecurity on swine finishing sites, Spronk said. Barns should be set up with a “clean/dirty line” at entry, and personnel should wash hands and change boots and coveralls on entry to a barn. When doing chores in barns, personnel should think through how they move through the barns, working the smallest, healthiest pigs first and moving toward the oldest pigs, he added.

Separate equipment and clothing should be used inside the barn when removing mortalities, with dedicated sleds/carts outside the barn to move dead animals to the rendering box. Mortality collection points should be far enough away from buildings to avoid the potential for cross traffic with where the rendering truck would travel, Spronk said.

He suggested that adopting composting or incineration could be better options for mortality management instead of rendering to avoid disease spread, especially as the industry considers the potential for foreign animal diseases such as African Swine Fever (ASF).

Spronk noted that if producers experience sudden or high death loss in their finisher units, it is important to contact a veterinarian because it is critical to determine which disease(s) are present. While ASF has a different pathogenesis, it shares some visible symptoms with APP, so it needs to be ruled out. Also, PRRS and influenza can be coinfections with APP that can trigger an APP outbreak.

According to Spronk, in the past, APP would have been flow dependent, so on an APP-positive sow farm, those pigs would get exposed in the farrowing crate and then when a stressor hits them in finishing, a disease outbreak would occur. A lot of systems moved to eliminate the virulent APP strains because outbreaks would be so costly producers couldn’t live with them.

Depopulation is the best way to clean it out completely, he said, noting that the cost of medication programs to control APP is expensive, so removing the positive sows from a system is the better option.

APP has been extremely costly to the industry, with the highest value mortality happening right before marketing. Once it gets into a system, it is harder to stop APP, Spronk concluded, leaving the best option to be prevention through good biosecurity and keeping the disease out of a pig production system.

How to manage herd closure for PRRS elimination

Herd closures to eliminate porcine reproductive and respiratory syndrome (PRRS) are on the increase due in part to the virulent variant identified as PRRS 1-4-4 L1C.

“PRRS 1-4-4 L1C has hit people hard,” reported Paul Yeske, DVM, Swine Vet Center in St. Peter, Minnesota. “The elimination process for this variant is what we’ve done for all PRRS viruses, and the program has been very successful at getting the herd to make PRRS-negative pigs.”

Yeske offered suggestions for a successful herd closure to eliminate PRRS from a farm.

Prepare for herd closure

The first step is increasing gilt inventory to cover the full closure time, which typically runs 210 to 240 days, according to Yeske.

“If there’s an on-site gilt developer where the farm is getting the gilts as Isoweans, they already have 6 months of gilts and only need to increase capacity for a couple months,” he said. If the farm has no on-site gilt development, they must either find another site to hold these animals or be able to fill the space available and live with the current inventory.

Just prior to closure, Yeske recommended implementing a feedback program that’s given to all sows and gilts to provide scour control for 6 to 8 months of the closure. “A lesson learned from PED (porcine epidemic diarrhea) was that we can help ourselves on scour control by doing a whole-herd feedback at the beginning of a herd closure,” he said.

Closure begins

Herd closure begins when sows are exposed with serum collected from the farm site. This occurs after the sow herd has recovered from the initial break and are eating and feeling good again. Some farms even wait until all replacements are on site.

He suggested following up 3 weeks later with a statistical sampling around the site to confirm the herd is positive. Make sure to obtain tests from all barns to ensure all animals are positive going forward.

“The injections start the clock ticking for 240 days and maybe longer, depending on how testing goes,” Yeske said. “Essentially, we wait for time to allow immunity to develop and shedding from sows to decrease.

“The theory is the virus will shed for a period of time, and the immune system will clear the virus from the sows,” he explained. “Since there are no animals in the herd that can be infected, theoretically the virus should die out on the farm, allowing for negative replacements to enter and not become infected.”

Throughout the herd closure, Yeske said the farm should focus on cleaning and disinfecting rooms, hallways, loadouts and any place weaned pigs move. Also, movement between litters should be minimized, and staff should be diligent about changing boots and coveralls when going back to handling young pigs. They should always work from youngest to oldest pigs, and change and clean up before going back to younger pigs.

Testing regimens

After 10 to 12 weeks of closure, collecting and testing piglet processing fluids begins, which will indicate the level of viremia in piglets. “Are we still positive or are we going negative?” he said. “We watch the Ct (cycle threshold) values and hope to see them go up. A lower number means more virus in the sample.”

Yeske recommended using processing fluids because samples are relatively easy to obtain, and it is less expensive than other testing methods. Plus, it essentially tests all piglets in a pooled sample, he added. Most farms pool a week’s worth of samples to reduce cost, yet still monitor to see if the herd is progressing.

When processing fluids start testing PRRS-negative, then piglets should be tested at weaning to see if they have remained negative through lactation. At this point, processing-fluid samples should be tested by room or day to help isolate the positive locations.

“Before weaning, most do blood testing, but you can use family oral fluids,” Yeske said. “With family oral fluids, hang the rope so the sow can chew on it first, and the piglets will chew on it too. Some litters respond better to family oral fluids than others, which is why most will use blood samples.

“The other option is to blood test the poorest-quality pigs, 30 to 60 a week or month, to establish if pigs are negative at weaning,” he added.

When to open herd

Depending on the farm, some use 60 days of negative tests at weaning, and others use 90 days of negative tests before ending the closure, according to Yeske.

“What we’ve seen is 210 days is the sweet spot for herd closures,” he said. “We tried 180 days and didn’t have good success. If you use 210 days, you have higher confidence that the herd is ready to take PRRS-negative gilts.

“And if you don’t get the piglets testing negative at 210 days, then we just wait. That’s when some people go to 240 days or longer. Remember, time is your friend in elimination programs versus ending the closure too soon.”

Closure ends

Once the closure is finished, the final step is repopulating. If a genetic supplier for a farm with an on-site gilt developer can provide a staged population, Yeske recommended refilling the gilt developer that way.

If only weaned pigs are available from the supplier to repopulate the herd, the farm will need a clean place to raise clean animals. “That’s a potential limitation, and you must think about that going into an elimination,” he said.

“Overall, the process of PRRS elimination is relatively inexpensive. And it’s been able to push the field virus out of herds,” Yeske added. “Some farms in pig-dense areas will maintain a vaccination status. They will be negative to the field virus but have a PRRS vaccine to have some herd immunity in case of a new virus exposure.”



Mycoplasma hyopneumoniae elimination becomes possible

Paul Yeske discusses Mycoplasma hyopneumoniae eliminate

Over the past two decades, the swine industry learned how to eliminate Mycoplasma hyopneumoniae (Mhp) from herds without depopulation/repopulation, according to Paul Yeske, DVM, Swine Vet Center, St. Peter, Minnesota. Yeske has been at the forefront of the efforts to eliminate the respiratory disease for clients.

The move to eliminate Mhp from herds has “really picked up momentum in the last 4 to 5 years,” Yeske added in an interview with Pig Health Today. In fact, efforts are underway to work towards areas or regions in Minnesota that are Mhp-free, with the end goal being the elimination of the disease from the state.

Why elimination?

When the industry moved toward high-health status sow herds, instability increased when Mhp-negative replacement animals entered positive herds and became infected just before farrowing, Yeske explained. Maintaining an Mhp-stable herd was a lot of work because the organism is very slow and takes a long time to infect animals and you must be deliberate in every step of the process. It also takes a long time for Mhp to clear from animals – up to 240 days. Gilt replacements need to be exposed by 80 days of age so they are not shedding the Mhp when they farrow.

As a result, many producers decided to eliminate it from their systems. Yeske noted that once a system has a good gilt-stabilization program, the herd is also set up well to go on to an elimination program.

“The herds we stocked that were negative from the beginning showed us the advantages of negative production,” he explained. “If you look at the literature, [the cost of Mhp] is anywhere from $2 to $10 a pig, and the average probably being in that $5 range. We know there’s a significant cost and a significant return.

“If we do a long-term closure, we’re talking about somewhere in that 3- to 4-month payback,” he continued. “If we do a heavy medication program and no closure, we’re talking about an 11- to 12-month payback.”

In addition, eliminating Mhp takes away the “add-on effects” when a herd experiences other infections like influenza and porcine reproductive and respiratory syndrome (PRRS) which can be even more costly.

“Producers have taken the approach —  ‘let’s take one off the table because we can’,” he said.

Statewide elimination efforts

Leading the work to eliminate Mhp from Minnesota is Maria Pieters, DVM, University of Minnesota. Yeske said the plan is in its early days but hopefully they’ll be able to get more herds involved and help reduce the potential for lateral risks of Mycoplasma spread.

“But it’s like any other voluntary program…there’s always going to be some period of time for adaption,” he said.

He doesn’t expect that in five years Mhp will be eliminated, but “hopefully at some point, I can still come back to the Leman Conference and say, ‘We used to have Mycoplasma‘.”

How to avoid winter ventilation pitfalls

During winter, swine facilities usually operate at minimum-ventilation rates. But if those rates aren’t correct, high humidity and excess gases will build up leading to increased disease and reduced growth rates, reported Sam Holst, DVM, Swine Vet Center, St. Peter, Minnesota.

“A good understanding of basic ventilation concepts and some routine monitoring to make sure everything is working properly will help set up a barn environment to optimize health and performance while also keeping utility costs in check,” he said. “A lot of ventilation mistakes result from efforts to try to save propane or other utility costs.”

Holst offered several tactics to avoid common winter ventilation mistakes that increase costs.

Calculate minimum ventilation

A big mistake that increases costs and reduces pig performance is an incorrect minimum-ventilation rate.

“Minimum ventilation is the amount of fresh air needed to be brought into the barn to help control humidity and gases like carbon dioxide and ammonia,” Holst explained.

“It’s important to get this correct because over-ventilating will waste propane and electricity leading to inflated utility costs,” he said. “On the flip side, if we under-ventilate, we’ll produce an environment that’s detrimental to health and performance.”

Minimum-ventilation rates should be calculated based on the number of pigs in the room and size of the fans on stage one. Use the following reference charts to help determine the minimum rates. Reference charts for required maximum cubic feet per minute (CFM) per pig and fan CFM output (Figure 1) and  (Figure 2) are helpful for these calculations. (Located at end of article.)

“It’s worth the time and effort to calculate the minimum-speed setting for stage one rather than use an arbitrary setting,” Holst added.

Set heater correctly

During the winter, heater and furnace use increase greatly. Holst stressed making sure the heater is set correctly to achieve consistent room temperature and limit propane waste. He’s seen propane use drop by several gallons per heater per day when settings were corrected.

One costly mistake is setting the heater shutoff temperature too close to the set-point temperature. Room temperature rises even after the furnace shuts off as it takes some time for the heated air to circulate and the probes in the building to detect the increase in room temperature. If the heater is programmed to shut off too close to set point, the room temperature will rise above the set point causing minimum-ventilation fans to speed up and exhaust heated air – essentially blowing recently burned propane right out of the building.

“A good way to finetune furnace settings is to make note of the current settings and watch the room temperature as it cycles through a heater on-and-off run,” Holst explained. “Ideally, once the heater shuts off, the room temperature should rise to just below set point without going over. If the temperature rises above set point, then adjust the heater setting so it shuts off further below set point. In most cases this will be 1.5˚F to 2.0˚F below set point.”

Check temperature probes, fans

All the temperature data fed into the controller to determine ventilation settings comes from temperature probes located in the facilities. If the probes are not functioning correctly, are placed in incorrect locations or are at the wrong  heights, information fed into the controller is inaccurate.

“If that happens, the result is an unfavorable barn environment,” Holst said.

Also, make sure fans are clean and not covered with  debris and dust. Just 1/8 inch of dust will reduce fan efficiency by 40%, he added.

Wrap curtains in plastic

“It can be beneficial to cover curtains with bubble wrap or plastic in the winter to help reduce drafts and heat loss,” Holst said.

His recommendation is to fully cover curtains on the north side of buildings with bubble wrap or plastic. On the south side, cover the curtains up to one foot from where it opens at the top so the curtains can be opened during a warm day.

Following these recommendations for winter ventilation should help keep utility costs in check and provide a healthy environment for pig growth through cold weather, he added.


Figure 1.


Figure 2.

Tighten up biosecurity protocols for supply and equipment entry

Erin Kettelkamp discusses biosecurity protocols on hog farms

All types of supplies and equipment enter a hog farm every week, putting an operation at risk of a disease outbreak. But improved biosecurity protocols with multiple layers help ensure items entering a farm are fully disinfected, reported Erin Kettelkamp, DVM, Swine Vet Center, St. Peter, Minnesota.

Some supplies are at greater risk than others. New supplies coming directly from warehouses probably won’t have a big risk of introducing pathogens. But if there’s cross contamination with other supplies or equipment traveling from other farms or housed at different warehouses within a system, she explained, it can be a cause for concern.

Kettelkamp detailed some of the updated biosecurity protocols for supply and equipment entry onto a farm.

Disinfecting supplies

Time with temperature is a simple way to disinfect items that are bulky or difficult to disinfect. Place the items in a segregated space and heat it to 100° F for 24 to 48 hours for removal of pathogens, she said.

Different fogging-type disinfectants may also work if a fumigation room is available. In addition, she said items can always be sprayed down or hand-wiped with disinfectant.

Maintenance tools shared with other farms in a system pose a much greater risk than new supplies entering a farm. “If tools have come from another sow farm or other swine operation, we know there’s been contact, and those items pose a risk, especially if there are pathogens associated with it,” Kettelkamp said.

She suggested a layered disinfection approach where a producer could utilize both time/temperature and disinfection, such as utilizing a fogging practice and layering that with spraying those items down.

Fogging practices

Kettelkamp spent some time during her veterinary studies at the University of Illinois looking at fogging practices. Originally, she said, foggers weren’t very effective because producers didn’t realize the fogged disinfectants weren’t permeating the room and acting like a true fog to disinfect the items in the fumigation room.

“Items were getting stacked close together where the droplets couldn’t reach,” she explained. “The droplets were just rising and falling, like you hand-sprayed them, so the bottoms weren’t getting contacted. There was shadowing. Sometimes we forgot to put disinfectant in the fogger, so that was a big hiccup and obviously that doesn’t work.”

In her university work, she searched for what could be done to make these systems work better. She identified a dry-fog system from human medicine that distributes the disinfectant using a very small particle size. A traditional fogger used more of a fine mist.

However, a true dry-fog system isn’t currently available commercially to swine farms because of durability and ease of use. “Hopefully, we’ll develop that technology so it is more readily available on farm,” she added.

In the meantime, Hurricane foggers, operated at the lowest flow rate with a hydrogen peroxide/paracetic acid blend, can provide a 90% efficacy rate for disinfection.

Auditing biosecurity

People are creatures of habit, Kettelkamp said, so how can bad habits be broken or good habits be reinforced so good biosecurity practices are maintained? Even if there is a procedure list in place, it’s always good to have a third party or another person from the farm come in and check to make sure the staff is following these practices, she recommended.

As far as shoring up biosecurity, Kettelkamp said it depends on the farm. Overall sanitation is very important and should not just be something that is talked about maybe once a month or whenever the veterinarian visits.

“[Biosecurity] needs to be a true culture to keep everything in order, and that stems from the office into the hallways, and exudes out into how clean we keep the farm in general and protecting it from all sorts of biosecurity risks,” she added. “It’s also making sure our barns are up to date and making sure our loadout chutes are getting clean and all of those things.”



Nursery transition tied to increase in pig scours

Swine producers may be seeing an increase in young pig scours, particularly in the early nursery, according to Ross Kiehne, DVM, Swine Vet Center, St. Peter, Minnesota.

Baby pigs do well in farrowing, but when they are weaned onto solid feed in the nursery, some of the pigs do not make that transition. After 3 to 6 days in the nursery, about 5% to 7% of pigs become thin and end up in a sick pen, he explained.

Kiehne has been doing more diagnostics trying to determine what diseases may be involved and then coming up with a management plan to help nursery operations do better.

Rotavirus main culprit

“The disease I keep coming up with is rotavirus,” he said. “I think what causes this is the change to the gut; then rotavirus sees an opportunity to cause some scour issues.

“It’s usually something that you can treat with just really good water,” he continued. “You can get them through it, but it doesn’t seem to be enough right now. The levels I’m finding in the guts are higher than I think we’ve had in the past.”

Kiehne is looking into different products that could be fed to young pigs to help with rotavirus. He’s working with nutritionists to make changes to feeding plans.

“We’ll try feed A versus feed B, and it might have more whey in it or less whey in it or more sugars, less sugars or whatever the nutritionists come up with,” he explained. “Then we’ll do a fecal scoring on them, and we’ve actually seen we can improve it with a change in nutrition.”

E. coli also a threat

Another culprit with young pig scours is Escherichia coli, Kiehne said, which can be easier to treat since there are antibiotics that can help with the infections. “But we’re finding some E. coli that are resistant to almost every antibiotic that we have,” he added.

Kiehne summarized the infection cascade as a harder-starting pig entering the nursery, getting some rotavirus, and then opportunistic pathogens like E. coli jumping in and becoming a real nuisance. “It’s usually a little worse in the winter because you can chill pigs, and you have to shut down barns and that kind of thing,” he added. “So I’m a little worried this winter could be another battle.”

Know the threats

To combat these nursery scours, Kiehne recommended getting out into the barns and posting pigs to see what is involved disease-wise.

“Then work with your nutritionist because…moving from a sow to solid feed is probably the most stress those pigs will ever go under,” he said. “Making sure it’s the best transition for these pigs will be very helpful.”