How to minimize summer’s impact on sow fertility

Sow reproductive performance drops off in the summer, and this year will be no different, according to Paul Yeske, DVM, Swine Vet Center, St. Peter, Minnesota.

“We typically see reproductive performance drop off as we get to week 29 through 40,” he said. “With hot weather in late May and early June, we may see it a little quicker than normal for us in the upper Midwest.”

To minimize the impact of seasonal infertility, Yeske recommends producers take steps to keep November and December farrowing numbers up.

Environmental impact

One main cause of seasonal infertility is overall environmental temperature, which can be handled several ways.

“Mitigation steps include increasing ventilation rates and using evaporative cooling like cool cells, drip coolers or misters or a combination to keep sows as comfortable as possible,” Yeske said.

“Typically, we see in this period more 21-day returns to heat, so sows are not conceiving as well,” he explained.

“In the past, those numbers would be more exaggerated. Today, they are in the range of 2% to 5% and not a huge number, but it does show up this time of year.”

Day length changes

The other cause of seasonal infertility is the change in day length.

“As day length shortens, the sows don’t want to be pregnant and farrow in the middle of the winter,” Yeske said.

“We see more irregular recycles. The sows were pregnant, and they either lose the pregnancy or reabsorb the litters.

“We want to be sure to identify these animals and decide if we are either going to get them rebred and back into the system, or cull them because performance is low,” he added. “We don’t want them sitting around taking up space and time.”

Yeske recommends heat checking early, because there are more 21-day recycles, and being diligent with second pregnancy checks around 50 to 60 days to pick up early pregnancy losses.

“Historically, we would see some sows not-in-pig as we get to November when those animals should be farrowing,” he explained.

“If we can get them identified now, then we don’t have them tie up space until November or December and not have litters.”

Some farms use lighting to help counter the changes in length of daylight. Timers keep lights on up to 16 hours a day in a bid to mimic the longest day of the year.

The impact of this lighting is hard to say for sure, but Yeske said many farms use this approach and it isn’t hard to do.

Increase breeding target if possible

Another option for minimizing seasonal infertility is to breed more animals if you have the room to do so.

“Farms will use their historical information to compensate by breeding, in general, 2% to 3% more animals, depending on what they’ve seen in the past,” Yeske explained.

Seasonal infertility used to be a much larger issue when boar services were required.

“Boars would get heat stressed, and semen quality would go down,” he said. “With nearly everything switching over to artificial insemination, we’ve been able to mitigate that issue.

“But seasonal infertility still shows up every year,” he added. “While the losses aren’t big, there are always some…so the quicker we get them identified, the quicker we can get animals bred back and into the system and be as efficient as possible.”

 

When swine medicine crossed over to human medicine

The tools used countless times to eradicate disease in sow herds and on hog farms became the tools to help pork packing plants reopen last spring after shutting down due to COVID-19. In an unusual turn of events, swine medicine crossed over to human medicine and helped quell COVID-19 outbreaks among plant workers and their families.

Veterinarians involved in the unprecedented effort spoke in a session at the 2021 American Association of Swine Veterinarians meeting. Tim Loula, DVM, led the effort with help from Paul Yeske, DVM, both of Swine Vet Center, St. Peter, Minnesota. Also closely involved were David Bomgaars, DVM, with RC Family Farms, Orange City, Iowa, and Brad Freking, DVM, New Fashion Pork, Jackson, Minnesota.

Plant closures

“When we started to hear about the COVID-19 problems, never did we imagine that slaughter capacity would be the biggest challenge that many producers and veterinarians would have to deal with,” Bomgaars related.

While pork-processing plants were deemed essential and could stay open during the pandemic, COVID-19 outbreaks sparked alarm among workers, their communities and local government officials. Soon, plants in Minnesota and Iowa cut back production and some completely closed.

A growing backlog of market hogs created great alarm in the pork industry. Producers and veterinarians worked on ways to handle backlogs while waiting for processors to reopen. But the processors didn’t know when that would happen.

Connecting with medical teams

“It just seemed like nobody was doing anything to get an answer on how to get these plants back running,” Bomgaars said. “Tim Loula and I discussed the need to get the human medical community involved in this process. We needed to better understand the prevalence, exposure, severity and asymptomatic rate of COVID-19.”

Bomgaars started seeking connections in the medical community. He contacted the CEO of his local hospital in Orange City and was provided a connection with Sanford Health, a major medical system in Sioux Falls, South Dakota. Sanford’s chief medical officer was willing to work with Bomgaars and other veterinarians to develop a plan for testing workers and getting packing plants back in operation.

“The medical doctors’ response was very encouraging,” Bomgaars related. “I was also talking with Roger Main, DVM, at the Iowa State University (ISU) Veterinary Diagnostic Lab. It was taking the state hygienic lab 10 to 12 days to get COVID-19 tests completed. The ISU lab has been running over a million PCR (polymerase chain reaction) tests a year. They helped the hygienic lab expand to run PCR tests. There was tremendous collaboration with human-health providers in Iowa.”

Both Loula and Bomgaars discussed their experiences eliminating disease in a hog population with the medical doctors. They explained how they used testing to assess the infection and immunity in populations of hogs. This same process could be used to assess COVID-19 infections in workers.

“Dr. Loula’s basic premise is we need to get testing and build confidence in what’s occurring so people will come back to work,” Bomgaars said. “Through collaboration with veterinarians, epidemiologists and health care providers, he developed a testing algorithm.”

The COVID-19 algorithm

The algorithm is a roadmap for handling COVID-19 test results and getting packing plants open (link to algorithm). All workers are tested either with a PCR or antibody test. Those testing positive on the PCR must quarantine and retest weekly until negative, which is when they can return to work. Workers who test negative can work unrestricted but must continue to be tested on a regular basis.

Workers testing positive on the antibody test must follow-up with a PCR test, according to the algorithm. If the PCR is negative, they can go to work. But if the test is positive, they must quarantine and be retested weekly by PCR until they have a negative test.

“This plan was to test everyone and keep them from spreading to other workers,” Bomgaars explained. “It definitely helped keep other processing plants operating.”

Workers were managed according to their health status to decrease health risk and promote worker safety. The negative PCR and immune (positive antibody test, negative PCR test) populations could work together. Initially it was proposed that these workers and families were housed in hotels or dorms to stay safe. The positive PCR with positive antibody test were at very low risk of shedding if showing no clinical signs. They were segregated in the plant or worked different shifts from the rest of the population.

“In the initial testing, it was amazing how many workers were asymptomatic,” Bomgaars said. “One plant had 2,400 people tested with 40% PCR positive and well over half showing no clinical signs. At another plant, 370 workers tested positive, and all were asymptomatic.”

Building worker trust

The algorithm helped packing plants get back in operation. And those that didn’t close were able to stay at near capacity by taking steps to test and manage workers to stop the spread of the disease.

“We also noticed a very personal response with education and explanations about the situation in languages that people could understand,” Bomgaars added.

During the really tough times of the pandemic, gift certificates were purchased from local restaurants for take-out food and given to plant workers. On weekends, Bomgaars said they had truckloads of food brought in and donated to the workers, too.

“Doing things that show you care about their health and family had a major impact on worker confidence that you want to do what’s best for them,” he added. “That’s a huge thing we learned in this process.”

The veterinarians also took home some good lessons about working with their human medical counterparts. “Local health workers understood that veterinarians are used to population medicine, and human medicine is more attuned to individuals,” Bomgaars explained. “They learned new methods of thinking. And the synergy that occurred in those situations was remarkably good. We may need this again.”

 

Pork industry struggled but found its footing during the COVID-19 crisis

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The pork industry entered one of its darkest periods in spring 2020 when COVID-19 forced the shutdown of several pork packing plants. Paul Yeske, DVM, Swine Vet Center in St. Peter, Minnesota, helped hog producers in the area work through the closures.

“Unfortunately, we were in the middle of the first plants that ended up closing,” Yeske said. “The biggest concern was that we didn’t know when the plants would open again, and we didn’t know [at] what capacity.

“As more things started to happen, the plants learned how to manage it more,” he continued. “I think that helped further down the road for people who were involved later to be less impacted.”

‘The wheels came off’

During the turmoil, the pork industry realized its efficient pork-producing and processing system had no room for errors.

“I think we learned just how good a system we had on a just-in-time delivery,” Yeske explained. “Producers and packers had been incentivized every step along the way to make the system more efficient and to have no slack in it.

“All of a sudden we couldn’t operate it, and then the wheels came off the wagon pretty fast.”

At that point, tough decisions faced producers, including euthanasia. “I think no one understands just how hard it is on people until they have to do it,” Yeske said. “No one can really appreciate that until they have to make that decision…and have to actually physically do the job.”

It was also something the pork industry thought it was ready to handle in the case of a foreign animal disease but really was not.

Best-laid plans gone awry

In 2019, Yeske was part of a table-top exercise with USDA to formulate plans for a foreign animal-disease outbreak. He said he thought they devised good plans to handle a catastrophe, but COVID-19 proved the plans were inadequate.

“Some of the things we thought we knew, we didn’t,” he said. “When you have to do a mass depopulation, you have to look at…how do we do it in a humane way? How do we do it in a safe way for the people? And how do we deal with the numbers?

“Ventilation shutdown was one of the things used in avian influenza outbreaks…It certainly was used here as well, but it’s not as easy as you think,” he added.

Always willing to innovate, the pork industry devised alternatives including the use of large-scale CO2. Trailers and later dump trailers with CO2 were among the best options, Yeske said. To help the pork industry, the state of Minnesota set up composting facilities to handle carcasses in two central locations, which could be done since no disease concern was involved.

Making the best of it

“I’d say today we’re probably better off to handle mass euthanasia if we have to than we were before, so that’s one of the good things that came out of this situation,” Yeske said.

Another positive is some farms used this time to reset herd health by closing and cleaning up.

Ironically, the spread of COVID-19 among hog farms was not a major issue. Hog farm staff already were well acquainted with biosecurity regimens and understood viral transmission of disease.

“The swine industry has been working on that for a number of years,” Yeske added. “I think we do have a leg up just because we had to deal with infectious disease for a long period of time, and we’ve got some good methods.”

Throughout the turmoil, Yeske says communication with everyone involved was crucial. “It takes a lot of communication and support…to make sure everybody understood what the goal was. We spent a lot of time on the phone talking to a lot of people, and I think that’s what it takes through those types of things…to make sure everybody’s at least understanding what’s going on.”

 

 

Highly infectious PRRS variant causes high mortalities on sow farms

A variant of the porcine reproductive and respiratory syndrome (PRRS) virus is taking a heavy toll on hog farms in southern Minnesota and northern Iowa. The variant, identified as PRRS 1-4-4, hits sow farms especially hard, causing 10% to 20% sow mortality and high mortalities in the nursery of 50% and even as high as 80%. In grow-finish units, mortalities are less but still can be significant, and growth rates drop dramatically.

“This PRRS virus hasn’t done anything we haven’t seen with PRRS; it’s just way more dramatic,” reported Paul Yeske, DVM, Swine Vet Center, St. Peter, Minnesota. Yeske talked about PRRS 1-4-4 as part of a webinar presented by the Swine Health Information Center and American Association of Swine Veterinarians.

Clinical signs

“From what we’ve seen on sow farms, this virus has a pretty distinct footprint,” Yeske explained. “You almost don’t have to wait for sequencing because you know what it looks like from the clinical signs.”

Symptoms include sows going off feed, abortions, increased sow mortality, increased piglet mortality, increased mummies and high post-weaning mortality.

“One thing that’s unique to this virus is it tends to move quickly through the herds once you see clinical signs,” he added. “You’ll start with four to five animals off feed and then 200 the next day and 300 the next. It marches through the herd quickly.

“The abortions start about the same time the animals go off feed. We’ve seen upwards of 3 to 5 weeks of production aborted and 10% to 20% of the sows dying in 2 to 3 weeks.

“Also, there’s high piglet mortality in the farrowing house…50% up to 80%, which I didn’t think was possible.”

In addition, neither vaccination nor prior exposure to the virus appears to reduce the outbreaks, he added, but it’s difficult to tell with the limited number of herds experiencing an outbreak.

High viremia

The PRRS 1-4-4 variant produces high levels of viremia, allowing it to spread easily in an area, Yeske explained. In addition, a milder winter with overcast, warm weather has helped the virus move around.

An increased number of diagnoses started in October 2020 in the two-state area, beginning with outbreaks in grow-finish sites and moving into sow farms.

“Certainly, the worst breaks have been, like we always see with PRRS, when you have viremic pigs leaving the sow farms,” he added. “But with this virus, we have lateral outbreaks even at the end of nursery with significant mortality.”

Yeske indicated some of the farms that broke were filtered, while others stayed negative even when located next to positive finishing sites and lots of positive pigs.

“Filters continue to show us they help but are not perfect,” he added. “The PRRS viral load is very high. There are lots of opportunities for this virus to get in, and if there’s a weakness, it’s likely going to find it.”

Stabilizing herds

After a 2- to 4-week period where herds experience the devastating losses, farms start to stabilize.

“We see sows start to return to normal,” Yeske said. “We see normal pigs born again but with very low, live born due to mummies, even though total born are still in the 16 to 17 pigs range. There are a lot of mummies on these farms but not necessarily all farms.”

As the herds continue to stabilize, Yeske said they will track them on the PRRS timeline to see if it runs similar to other strains they have dealt with in the past.

Review biosecurity

The big lesson Yeske hopes producers will learn from these outbreaks is the importance of a biosecurity plan that is strictly followed. He urges everyone to review their biosecurity.

“Identify the greatest area of risk in your herd,” he explained. “Risk is how likely something is to come into the herd and then how many times a week do you do that activity. Multiply those two to give you the risk.

“Then improve any weakness in your biosecurity system, and do it sooner rather than later,” he added. “Don’t wait to identify it in your outbreak investigation.”

 

 

Tactics to reset herd health learned during COVID-19

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Pork producers learned many lessons during the COVID-19 crisis, including how to improve herd health.

“The goal was, how can we do something to help us on the back side of [COVID-19]?” related Paul Yeske, DVM, Swine Vet Center, St. Peter, Minnesota. “Our thoughts were, is there any way we can help farms come out of this healthier?

“We had to do some depopulations anyway, and could we do something that might improve the health status long term for the herd and hopefully for the industry?” he explained.

Yeske already had plenty of experience with disease elimination programs. He figured they could use those methods with some new options to help producers attain better herd-health status when the crisis was over.

Depopulation for health, genetics

Typically, depopulation is planned to target specific diseases, but it can eliminate other herd problems, too.

“You can also make a genetic change,” Yeske said. “If you’ve got a bad parity structure or a bad parity distribution, you can handle all those things with one process. That’s the advantage of depopulation. The disadvantage is it takes a while to come back into production.”

During COVID, some producers delayed herd repopulation to wait for a better market. Other producers decided to repopulate right away and purchased healthy pigs to get the herd up and running.

Herd closures popular option

“Herd closures have been a very successful technique for porcine reproductive and respiratory syndrome (PRRS) mycoplasma and many of the smaller bacterial diseases that we deal with,” Yeske said. “We’ve been able to stabilize a herd.”

Herd closures work well in multiple-site production with farrow-to-weaning on one site and wean-to-finish on other sites. Once the site is totally exposed to allow herd immunity to develop and stop shedding, then new negative animals are brought back into the herd.

There were variations on this process, though. Yeske said some units did the load, close, expose and then downsized by not adding outside animals.

Farrowing unit clean-out

Another option used in this crisis involves emptying an entire farrowing barn at once to break the transmission of disease.

“We always have multiple stages of pigs in most farrowing houses, particularly the weekly systems,” Yeske said. “We empty out the farrowing barn like we do in a batch system to help break the transmission chains for influenza, PRRS and some of those. This helps speed up the process.”

This option works well for farms in a herd closure but still experiencing disease shedding in farrowing or want to speed up the process. Completely emptying and disinfecting the farrowing building breaks the disease cycle.

Other options

Some farms used this time to transition to batch farrowing because it reduces the number of animals in the system, Yeske said. “They might have waited a little longer to go there, but it was a good opportunity to do it.”

Other farms increased weaning age. The goal was to produce a little older weaned pig that is more stable when it moves to the wean-to-finish facility, he explained.

Making the decision

Deciding when and how to clean up a herd has always been a difficult decision. “And in stressful situations, it’s more challenging to make them,” Yeske admitted. “But certainly where some herds were experiencing some very difficult problems, it made sense.

“Long term, what we’ve seen out of the closures is that they’ll have a healthier pig on the back end. And for the depops, you hit the restart button.

“But you have to make sure you’re doing all the biosecurity things, too, as you come back in when you’re on the healthier side,” he cautioned.

 

 

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.