How hog farms used COVID-19 to improve herd health status

When faced with the COVID-19 crisis, some producers made the most of the situation by depopulating to get rid of disease issues, according to Paul Yeske, DVM, Swine Vet Center, St. Peter, Minnesota.

“People looked at ways to take advantage of these opportunities to improve the health status of herds,” Yeske explained. “Certainly, market prices had a major impact on us…The question often asked was, ‘Are you better off to lose less?’ Many people were frustrated dealing with sick pigs that were unlikely to be profitable.”

Economics of disease elimination

In budget models, eliminating disease pays off for hog farms. Even modest changes in overall productivity add up, Yeske said. For example, a 1,000-sow farm undergoing a disease elimination for porcine reproductive and respiratory syndrome (PRRS) returned an extra $13 per pig or $420 per sow to the bottom line.

The cost of eliminating disease varies by method used. A depopulation/repopulation with off-site breeding to reduce downtime costs $12 per sow and takes 1 year for payback. Without off-site breeding, the cost is $20 per sow and up to 2 years for payback.

A herd closure used to stabilize health is a much cheaper route for clean-up. Yeske said the cost of a closure ranges from $1.50 to $3 a sow with payback in 1 to 3 months.

Depopulation/repopulation considerations

While the cost for depopulating is high, it is successful. “Depopulation is a time-honored method for improving health status,” Yeske said. “It works very well for a number of different diseases. When executed properly, it is nearly 100% effective.”

Many herds were dealing with tough strains of PRRS, leading to death loss downstream in commingled pigs. Other health problems like mycoplasma also were present.

“We know sow herds are very likely to perform much better than previously when they start with a healthy herd,” he said. “The new pigs beat the old pigs to market before we’re done.”

This was also a good time for farms to correct parity-distribution imbalances and to make genetic changes.

But repopulation during COVID-19 was very different. Yeske said this was the first time he’d seen clients depopulate and then wait to repopulate. Some farms were even “mothballed” indefinitely.

“Repopulation is always a bit of a challenge,” he added. “Timing is always the hard part. If you start too late you miss the higher markets, and if too early, you lose too much money before you get a chance to profit from the decision.”

Herd closures

In the last few years, herd closures to stabilize herd health gained popularity, especially with multiple-site farms.

“The farrow-wean farms can be stabilized, and no other pigs brought on site,” Yeske said. “It allows the site to develop good, solid immunity. Then we empty wean-finish sites and do a repop on each of those. It’s the old ‘load, close and homogenize’ system.

“What we’ve learned over time is we can do it without losses in production,” he added. The herd closures are good options for diseases like PRRS, mycoplasma, influenza, porcine epidemic diarrhea virus, transmissible gastro-enteritis, etc.

A different method used by a few hog farms was closing the herd and not loading it. “It accomplishes the same goal of improving health but with less pigs in the system,” Yeske said. “It may not affect the numbers as much as you think.”

Some producers created a hole in production to allow a herd to clean out and reduce numbers in the system, he explained. Farrowing was left empty while stabilizing disease.

Other producers euthanized pigs to create a hole in production, reducing numbers and allowing pigs to stabilize. They purchased high-health pigs to replace inventory.

Weaning age, batch farrowing

Some hog farms made adjustments to weaning age during the COVID-19 crisis. Yeske said these farms were using a 19-day weaning age, but it wasn’t working well. After returning to a 21-day weaning age, the sows performed better with more born live, a shorter wean-to-first-service time and better farrowing rates. The pigs also were easier to start on feed and posted a better average daily gain.

Other farms took the opportunity to convert to batch farrowing. Synchronization products available today make this production model more successful than in the past.

“The advantages to batch farrowing are on the wean-to-finish performance,” Yeske said. “You can run all in, all out by site and can run bigger sites. It improves average daily gain and mortality. You can make a small farm perform like a large farm.”

 

Packing plant closures lead to big lessons learned from COVID-19

Nothing in his lifetime could have prepared Paul Yeske, veterinarian at Swine Vet Center, for the painful fallout from COVID-19 that hit the clinic and its clients.

In early April 2020, major packing plants taking most of their clients’ hogs started shutting down. At one point, processing capacity dropped 45%, with most plant closures occurring in Minnesota, South Dakota and Iowa as well as other plants slowing down and reducing capacity.

“Plant closures were one of those things we didn’t see coming,” related Yeske, whose clinic is located in St. Peter, Minnesota. “We were in the middle of it. It had a major impact on our producers and clients.”

Yeske and his colleagues devised contingency plans for handling a glut of market-weight pigs with no place to go. Fortunately, many others including producers jumped in to help. Yeske discussed the harrowing situation and outcomes during a talk at the 2020 Leman Swine Conference held virtually in mid-September.

Penalty for efficiency

“The industry was always rewarded for building better efficiency. But we soon learned there was a penalty when that comes apart,” Yeske explained. “There was no room for problems to develop. [It was like] being on an escalator and the people at the top aren’t moving away and you are trapped. I think everybody this spring felt that pressure and felt trapped.”

The first step before closures occurred was slowing down pig growth. Producers warmed up the temperatures in buildings, tightened up feeders, added fiber to diets and made other recommended nutritional changes.

But drastic action was needed to handle the massive loss of packing capacity as plant shutdowns occurred. Depopulation and disposal were needed to handle the overflow of pigs.

Depopulation lessons

In the past, Yeske said he participated in exercises for handling foreign animal-disease outbreaks, which involved discussions about mass depopulation. But it didn’t fully prepare him for this event.

“Like many other things, it’s much different to do it than to plan and talk about it,” he said. “We really learned it takes a lot of logistics. Some of these systems had to act like a packing plant — we were getting rid of that many pigs. We started out using traditional methods…but our veterinarians were saying we had to come up with a better plan.

“The challenge is how to do mass depopulation [in] the best way to euthanize the pig and keep people safe,” he added. “The silver lining out of this is we now have better methods for mass depopulation…we know what works and, more importantly, what doesn’t work.”

Some of the better options include the use of trucks and shipping containers with CO2 and ventilation shutdowns. Work on these options continues. For example, North Carolina State University is developing shipping containers with CO2 to handle mass depopulation.

Disposal of carcasses

Disposal was also a challenge with plants shut down, Yeske said. But because not everyone depopulated at the same time and there was also less restaurant waste, they were able to get most of the carcasses through rendering plants.

A large number of carcasses were still available to test the grind-and-compost method. Minnesota used two centralized locations for composting the carcasses.

“We did learn how to compost,” Yeske said. The grinding method really helped speed up the process by getting the compost to temperature faster, which will be important in a foreign animal-disease situation. It also requires less area to get it done.

Other lessons

Some hog farms with significant health issues used this crisis to depopulate. They also waited to repopulate when the market was more favorable. “I have never seen farms that were mothballed,” Yeske admitted.

“Some producers went through and only fed good-quality pigs and euthanized the bottom end,” he said. “Some aborted sows to make holes in production to allow farms to stabilize health and reduce numbers in the system.”

Yeske also learned untraditional markets can offer big help. “We were able to get pigs out of the system. Some smaller plants geared up. Local lockers are still booked for 6 to 12 months. Sale barns moved a lot of pigs. And university meat labs set up to do custom slaughter for food shelves.”

Figures from the Minnesota Pork Producers show the untraditional markets moved a lot of hogs. About 250,000 pigs were taken out of the system and given away. Another 350,000 pigs were euthanized.

Future preparation

“What do we do in the future so we don’t have to face this again?” Yeske asked. “We talk about building slack capacity in production systems, but it’s too difficult, particularly with economics today. There is some discussion with packing plants about building slack capacity, but they are built around efficiency as well.”

Instead, Yeske suggested using a COVID-type situation to make the industry healthier. He looks back and wishes the industry had taken advantage of the shutdowns to improve herd health. In the future, the industry needs to help itself and set up funds like what they did with the Swine Health Information Center. Funding will help the industry be ready to act when unexpected situations occur and not left trying to react in the face of the battle.

“There would be opportunities to capture this and come out as a healthier industry,” he said. “Unfortunately, I think we missed that opportunity [with COVID-19].

“As we know from the past, those willing to adapt will survive,” Yeske continued. “There will be a new normal as we go forward. And we have to find some funding to help us go through these things in the future…We have to remember we still live in one of the best places to raise pork.”

 

Is reducing inflammation key to improving PRRS control?

By JoAnn Alumbaugh
Farm Journal’s Pork

Porcine reproductive and respiratory syndrome (PRRS) continues to be a critical concern to the U.S. pork industry. The combined production losses associated with PRRS in breeding and growing-pig herds are estimated at more than $663 million, and that doesn’t include secondary infections.

There is usually a high degree of interaction between pathogens, and it has been shown in previous studies that a reduction in PRRS also causes a reduction in the impact of co-infections like Streptococcus suis, Haemophilus parasuis, Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae and Salmonella spp.

PRRS is a viral disease, yet it is known to cause considerable inflammation in the respiratory system. In PRRS-infected gilts, endometrial inflammation and vasculitis increased progressively from 2 to 14 days post-inoculation.

Inflammation may be one of the factors associated with abortions in the presence of PRRS as well. Inflammation at the point of attachment of the uterus with the placenta may disrupt the fetus, resulting in loss of the fetus or the formation of the mummy, says Paul Yeske, DVM, with the Swine Vet Center in St. Peter, MN.

“There are certainly some things we don’t understand, and we have changed our thought processes on how we can manage these things,” Yeske says, adding that PRRS-infected pigs are more vulnerable to secondary bacterial infections requiring an antibiotic therapy, so having an antibiotic and an anti-inflammatory can be a good combination.

“The inflammatory response is a call to action of the whole pig,” says John Deen, DVM, PhD, professor at the University of Minnesota. “It affects behavior, reproduction, metabolism and even the pig’s ability to survive. It has to be taken seriously, especially in the face of a disease like PRRS. We need to provide extra care for animals to recognize when they cannot cope with the insults they have in front of them.”

Inflammation is usually associated with bacterial infections; in which case an antibiotic would be used to help reduce the inflammation that accompanies an infection. Now, researchers are learning more about the role of inflammation in viral infections like PRRS.

Research findings

Andre Buret, PhD, a professor in the department of biological sciences at the University of Calgary, Canada, has done extensive research on the immunomodulation properties of an injectable antibiotic on pigs infected with PRRS. Immunomodulation refers to a change in the body’s immune system, caused by agents that activate or suppress its function.

While no vaccine against PRRS provides 100% protection, some injectable antibiotics have been shown to exhibit potent immune-modulating effects — that is, they activate, boost or restore normal immune function once it’s damaged. That in turn can help better withstand the inflammatory responses associated with PRRS.

“Treatment options to control PRRS outbreaks are limited, and the efficacy of vaccines is thwarted by the antigenic variability of PRRSV,” Buret says.

He explains that PRRS can create immune dysregulation — a breakdown of the immune system, in other words — that makes the host more susceptible to opportunistic pathogens. Disease severity is closely related to the ability of the virus to disrupt the functions of the macrophage — a large white blood cell that is an important part of the immune system — and induce inflammation, he adds. For those reasons, he theorizes that targeting inflammation with an antibiotic used for bacterial co-infections might be a critical element in managing the costly PRRS virus.

In laboratory experiments conducted by Buret and his team, using an injectable macrolide antibiotic did not change intracellular or extracellular viral titers, nor did it alter expression of the viral receptors (CD163 and CD169) on porcine macrophages. It did yield other benefits, however.

“In contrast, [the antibiotic] exhibited potent immunomodulating properties, which therefore occurred in the absence of any direct antiviral effects against PRRSV,” Buret says. “These data demonstrate that [the injectable antibiotic used in the study] inhibits PRRSV-induced inflammatory responses in porcine macrophages and protects against the phagocytic impairment caused by the virus.”

The antibiotic was also shown to inhibit the production of pro-inflammatory mediators (CXCL-8, LTB4) and promote the production of pro-resolving mediators (LXA4), Buret explains.

Research evolution

Buret’s work with pigs and PRRS marked an evolution in the battle against the PRRS virus.

“We spent two and a half years of research…and we were able to demonstrate [the antibiotic] may very well have benefits in the context of PRRS viral infections based on what we discovered,” he says. “It seems to disarm the ability of the virus to prevent host immunity to clean up bacteria in the lungs.”

If a producer has the background of a viral infection like PRRS on the farm, the engulfment of foreign particles by the macrophages is compromised. As a result, the lung cannot clean itself anymore and the pigs are more prone to secondary infections, Buret says.

“The virus alone triggers an inflammatory response and impairs phagocytic clearance by macrophages. We observed that this type of antibiotic protects against both effects. It’s really one discovery leading to the next,” he adds.

“As it turns out, our discoveries have established for the first time that controlling inflammation at the same time as you control the microbe is the best way to deal with these diseases clinically,” Buret says.

Anecdotal evidence

Swine Vet Center’s Yeske recalls working with a client who had a PRRS break in a herd that was being treated with an antibiotic as part of a Mycoplasma hyopneumoniae (M. hyo) elimination program.

“We were treating the herd with an antibiotic [for M. hyo] and [it] broke with PRRS in the middle of the M. hyo elimination,” Yeske says. “You never know if an outbreak is going to be as severe from herd to herd as other similar outbreaks, even if the virus is similar, but we saw much less of an impact in this particular case as we went through and treated the animals for the M. hyo elimination. We had fewer clinical signs than we would have expected to see, based on other very similar farms that had essentially the same virus. It does make us think about some of the mechanisms that may be going on [associated with inflammation].”

Because PRRS is often a co-infection with bacterial infections that also cause inflammation, antibiotic treatments for M. hyo might yield secondary benefits that make the effects of PRRS less severe.

This is a new approach for veterinarians to consider when PRRS is present in herds infected with swine respiratory disease, Buret says. The antibiotic controlled the bacterial infection, which in turn helped to not only reduce inflammation but also the host’s response to it — a process that, if left unchecked, ultimately causes pulmonary failure and death.

“Research in live pigs is warranted to assess the potential clinical benefits of this antibiotic in the context of virally induced inflammation and tissue injury,” Buret says.

(Read the article at Farm Journal’s PORK.)

Batch farrowing makes a comeback on small- to medium-sized sow farms

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The practice of farrowing sows in groups and not continuously is making a reappearance as small- to medium-sized sow farms seek ways to stay competitive, reports Paul Yeske, DVM, veterinarian with Swine Vet Center.

Yeske has seen many farms under 2,500 sows, and a few larger ones, switch to batch farrowing so they can wean enough pigs in a group to fill a large grow-finish facility. It really depends on what downstream flow looks like.

“It allows these farms to act like bigger farms and be able to run a site all-in, all-out and be reasonably sized,” he added.

Back to batch farrowing

Batch farrowing historically was popular when Yeske started his career.

“The trouble with batches is they fell apart because we didn’t have good control of the reproductive cycle of the gilts,” he said. “It took a lot of gilts and a lot of inventory to make sure you kept your batches full. When batches didn’t stay full…the breeding windows opened, and all of a sudden, you’re continuous farrowing.

“Now we have some tools that allow us to synchronize the gilts, and we can get them into the breeding window and…keep the groups very tight,” Yeske said.

Health benefits

The ability to break disease cycles with batch farrowing versus continuous flow offers attractive health benefits.

“You get the opportunity to have the farrowing house completely empty, and for some pathogens, it gives us the breaks we need,” Yeske said.

“Some of these disease cycles break down faster, and it helps to improve the health status, particularly in the wean-to-finish pigs,” he added. “Granted, the wean-to-finish is the motivation, but having these pathogens under control also benefits the sow herd.”

Improved wean-to-finish performance of batch-farrowed pigs makes them attractive to conventional-sized finishing sites. It makes the potential to not have to commingle flow or have multiple age groups on the same site.

The drawbacks

The downside to batch farrowing is a lot of the work falls within a 10-day timeframe, while continuous flow spreads the farrowing work over 4 weeks.

“For the people on the farrowing side, batch farrowing isn’t necessarily friendly,” Yeske said. “It makes it more of a challenge to manage the surges of work. One advantage, though, is that you do get the opportunity to specialize skills in these times and only concentrate on one activity at a time. This allows for better focus than having to balance multiple tasks at once.

“But from the wean-to-finishing side, you do get a single-source, good number of pigs. And as you go into [this], you need to think about it based upon the wean-to-finish performance,” he added.

 

Prepare for African swine fever outbreak with Secure Pork Supply plan

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A growing threat of African swine fever (ASF) has convinced US pork producers to prepare for the worst with a Secure Pork Supply plan, reports Paul Yeske, DVM, Swine Vet Center, St. Peter, Minnesota.

“The Secure Pork Supply (SPS) plan was put together as a mission to improve biosecurity and to help make sure [if] a foreign animal disease enters the country that we have a plan for farms to survive,” he said.

The voluntary SPS plans help producers implement a more complete biosecurity plan to assure others that their herd is negative. This will allow the farm to continue business and move pigs, if needed, in the face of a foreign animal disease outbreak such as ASF.

SPS plans underway

In most cases, veterinarians are helping producers work through the plans.

“That’s been one of our roles — work with clients to set up the biosecurity plans, to help designate the sites, draw the maps of the sites and help make sure the program is set up properly,” Yeske said.

“Many of our clients have started the process and many have already completed it,” he added.

In some states, veterinarians are asked to validate the SPS procedures are correctly implemented.

Veterinarians also may be needed to train others on how to test for ASF if the disease is identified in the US. “It becomes a very big biosecurity risk to go out and do testing on the positive or suspect farms,” Yeske said.

“One of the things that’s being looked at is can we do like they did with avian influenza. They had trained people who were able to go out and collect samples. This will be once we’ve had a positive, and we’re in the situation where we need to know the status of many herds,” he explained.

Next-level biosecurity

Even without a foreign animal-disease outbreak, SPS plans are valuable.

“Secure Pork Supply takes biosecurity to the next level,” Yeske said. “I think these plans are a great opportunity to review some of the procedures you’re already doing and strengthen some of the weak areas.

“I hope we never have to use it,” he added. “The reality is that I think we all have to really pay attention to this one because we’ve seen just how fast it can move with other diseases such as porcine epidemic diarrhea virus.”

For more information about Secure Pork Supply, visit securepork.org.

 

 

Mycoplasma elimination possible, but more difficult on farrow-to-finish sites

With the right program in place, eliminating mycoplasma pneumonia is possible on many hog farms. Farrow-to-finish sites are still the most difficult to clean up, however, reported Swine Vet Center’s Paul Yeske, DVM.

He has carried out multiple mycoplasma-elimination efforts on different types of hog farms with good success.

“The farms that are easiest [to eliminate mycoplasma] are the farms that are multi-site production, where we have a farrow-to-wean site…The herds that have all ages of pigs on site, that’s where the challenge is going to be,” he said.

Long-term herd closure

The best method for eliminating mycoplasma from a farrow-to-wean site requires herd closure to allow the animals to develop immunity and stop shedding. Research shows the disease’s causative organism, Mycoplasma hyopneumoniae, can be shed up to 240 days.

“We expose all the animals up front to make sure everybody’s exposed and immune, and then we wait 240 days,” Yeske explained. “At the end, we use some medication as a secondary step to make sure we’ve controlled everything before we bring the negative animals back in.”

The advantage of this elimination program is a short payback period of a few months, he added. A depopulation-repopulation elimination takes a couple of years to pay back the expense.

Farrow-to-finish options

Farms with all ages of pigs on one site require more time and expense to eliminate mycoplasma. A partial depopulation that empties the nursery and finishing stages for a short time is one solution, according to Yeske.

“I think there are ways we can do [elimination] on really any given farm,” he said. “It’s just finding creative ways to do it. And the depopulation-repopulation would certainly be an option.”

Complete elimination

Could mycoplasma be completely eliminated from US herds?

“I think it’s a disease that could be eliminated,” Yeske stated. He cited research that showed a low likelihood of M. hyo reinfection from neighboring finishing units.

“If you have a mycoplasma problem in your system, you likely have a system problem,” he said. “It’s not the neighborhood problem.”

Plus, the future holds new technologies like better diagnostics, new antibiotics and new testing procedures.

“Are there ways we can manipulate these tools to eliminate disease so we don’t have to deal with it?” he added. “What I’ve tried to do over time is, when something new comes out, [to determine] how could we leverage this into a new tool.”

In the past, the pork industry has eliminated diseases like pseudorabies without depopulation-repopulation.

“We had a very good vaccine with pseudorabies, and we were able to do eliminations by test and removal,” Yeske recalled. “Mycoplasma is another bug that lends itself well to herd closure and elimination.”

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Is fogging an M. hyo-elimination option for your swine herd?

Paul Yeske, DVM, with the Swine Vet Center in St. Peter, Minn., has seen repeatable success with Mycoplasma hyopneumoniae (M. hyo) elimination, along with the downstream effect of lower cost of production, better average daily gain, better feed efficiency and lower mortality. He estimates the benefit of M. hyo elimination to be in the $3 to $4 range per pig, conservatively, with some herds seeing a benefit of as much as $10 per pig when other diseases are eliminated at the same time. Now, the relatively new protocol of fogging a barn may make M. hyo elimination even more attractive.

This technology came out of the frustration of trying to evenly and efficiently expose animals to the bacterium, Yeske told Pig Health Today. Fogging allows for faster exposure to establish “time zero” for elimination, so gilts can be stable by the time they enter the sow herd.

“That reduction of time for M. hyo to spread from animal to animal in a natural way is probably the biggest advantage,” he said. Previously, Yeske would use intratracheal exposure of seeder animals, but said, “It’s a lot of work and you still have slow spread from animal to animal. Fogging has been very successful for us, although it’s still new technology and there are some lessons to learn as we go forward.”

Research needed

Fogging appears to be an effective method for M. hyo elimination, but Yeske said critical questions need to be answered on the technology:

  • How long can the inoculums be stored?
  • How long can the lungs used for the inoculum be stored if the herd is kept positive?
  • What’s the best media to use for exposure?
  • Should an M. hyo media be used, or can we use phosphate buffered saline?
  • Which products work best for fogging in terms of storage and/or the fogging procedure?
  • What’s the right dosage and volume level?

“So far it’s been very good, even with the experimental method we’ve used, but I think there’s an opportunity for it to be better,” Yeske said, adding that, “We just need to support the researchers to do the difficult work to answer these questions.”

Other methods also effective

Yeske said depopulation/repopulation is the “tried and true” method that works every time but it’s also the most expensive. It’s difficult for people to invest the money unless there are other compelling reasons, such as additional disease challenges or parity re-distribution, he noted.

The herd closure model is to keep a herd closed (no new introductions) beyond 240 days, Yeske said. Hee recommends medicating the sow herd and piglets at the end of the closure, which allowed the pigs’ immune systems to help as much as possible. Timing varies, but this model has been the most successful and has had the least amount of impact on production.

“We’ve been in the 75% to 80% success rate over time and it’s been the most repeatable system,” he said. “Generally, mycoplasma elimination has been done in conjunction with other diseases, such as porcine reproductive and respiratory syndrome (PRRS). It just adds a little more time to standard PRRS-closure and you also get rid of the M. hyo,” he said.

Another method involves whole-herd medication, without a herd closure, but Yeske said the success rate is closer to 50% when medication is done without herd closure.

“If we do limited-herd closure (150-240 days) and then medicate at the end, the process has been more successful and closer to the long-term closure success rates,” he said.

Useful tool for control or elimination

Fogging may not be a silver bullet, but Yeske said it’s a useful tool for M. hyo control, “whether you’re doing ongoing control and acclimating replacements into the herd, or you’re looking at elimination. The technology is fairly inexpensive, so it’s about having your herd veterinarian help set up the program to make sure you’re doing everything the right way.”

Yeske is often asked how likely a herd is to stay negative if a producer goes through the Mycoplasma-elimination process, especially in pig-dense areas.

“We did some research two years ago and found that lateral introductions happen, but they are rare,” Yeske said. “We saw 94% of the herds stay negative, even in pig-dense areas.”

He recommended producers and veterinarians work on herd stabilization, with consideration given to elimination if other issues are impacting the herd.