Late-weaned, parity-1 sows benefit from skipped cycle

New gilts entering a farrowing room face some big demands for animals still maturing while supporting their first litters.

“We can be pretty demanding as far as what we ask from gilts, especially once they get ramped up in lactation,” reported Henry Johnson, DVM, Swine Vet Center, St. Peter, Minnesota.

“Because we want that gilt underline developed for subsequent farrows, gilts end up weaning a lot of pigs and putting out a lot of milk in their first time up in the farrowing house,” he explained.

As a result, some gilts use up their fat reserves during lactation and come back into the breeding barn thin. Many times, these will also be the sows coming into heat on day 6 or 7.

Instead of breeding these sows, Johnson suggests skipping a cycle to let them put on weight and become more productive sows in the herd.

Skip a cycle — bigger litter

“We see an advantage to skipping some of these sows we call late weaned,” Johnson said. “Most of the time these parity-1 (P1) sows performed well and weaned a lot of pigs. But they need extra time to recondition.”

When these sows are bred on day 6, 7 or 8, they become some of the herd’s worst performers on a total-born basis for the farm, according to Johnson.

“If we skip a late-wean sow to give her 21 days to cycle again and provide enough feed to allow her to put some condition back on, then she is ready for that next service,” he said. “We will see a more efficient animal in breeding and one that will provide a higher total born when it comes time to have that next litter.”

Target animal

A farm can easily set up the criteria for staff to determine P1 sows that will benefit from a skipped cycle.

“If a sow comes back in heat at 6 days or later, most likely it will be a P1 and she will be very thin,” Johnson said. “It keeps it pretty simple for the farm staff.”

The number of P1 sows falling into this late-weaned and underconditioned category is typically about 5% of the breed group. This also represents a 5% drag on the breed group if those sows are bred first cycle.

“That’s part of the reason why it makes sense to give these P1 sows this extra time,” Johnson said. The extra cost for space and feed will be repaid with increased performance.

“You take the five worst-performing animals and put them in the five-best category and the entire group average shifts up dramatically,” he added.

“Then it quickly turns into a different story…I have all these pigs and how do I keep them alive.”


Don’t forget biocontainment of disease when following biosecurity plans

The latest disease outbreaks fueled by new disease variants are good reminders that the best biosecurity plans must include strategies to keep disease contained within a barn as well as ways to prevent new disease outbreaks.

“We have to remember it’s not only bio-exclusion where we don’t want to bring in new, harmful disease onto a farm, but we also want to make sure that we contain diseases, so we are not transmitting it throughout the area or to any other barns within the system,” reported Erin Kettelkamp, DVM, Swine Vet Center.

“We have to worry about all the different movements that go on around the farm,” she explained. “Ultimately, we want to minimize any type of exposure rate. The fewer movement of either people, pigs or supplies, the better.”

Audits necessary

With fall arriving, Kettelkamp recommends hog farms conduct audits to make sure biosecurity plans cover all necessary areas and are being followed correctly.

“This time of year, it’s a good idea to have either a system’s audit or a veterinarian do an audit,” she said. “It gives another set of eyes on the farm to evaluate if we are doing what we say we are when following processes or make improvements.”

The audits should be conducted at least annually by a veterinarian or quarterly by an impartial employee or a veterinarian.

“We can’t always assume our procedures are being completed as we had them written down on paper,” she explained. “That’s why auditing all these processes is important.”

Kettelkamp conducts a variety of biosecurity audits ranging from a general farm audits to specific audits like truck washes and filtration systems. She offered strategies for making biosecurity plans stronger.

Control supply entry

Supply orders for the farm should be coordinated to reduce the number of deliveries to a farm. Instead of multiple deliveries in a week, supply orders are minimized to a couple a month.

For other types of supplies and equipment, the best strategy is dedicating the items to a specific farm.

“It is something like moving weigh scales or bringing in any other type of supplies such as those we plan to use on the farm for sampling,” she said. “Cost is a big concern. But if there is any way to have all these items dedicated to each site that’s good.”

If these items must be moved between farms, cleaning and disinfecting methods must be followed every single time.

“Other things to think about on farms is if they are filtered,” Kettelkamp said. “Continue to assess the filters and make sure it’s an airtight space.

“If focusing on sow farms, don’t forget about protecting the health of downstream pigs. We must be aware of where we put disease-challenged pigs or where we keep clean pigs. We also should evaluate biosecurity in a similar way as a sow farm, and the same with people movements.”

Control equipment movement

Another area of biosecurity concern is manure handling.

“We want to be diligent [and not hasty] about how we handle all that equipment,” Kettelkamp said. “Make sure to sanitize and move it between farms in a biosecure way.”

Ideally, the equipment should be segregated so anything used on a farm experiencing a disease outbreak is not then used on a clean farm. If this isn’t possible, then the focus should be on cleaning and sanitizing with downtime before the equipment is moved to other farms.

Similar rules also apply to feed mill trucks and other contractors entering the farm, like a service crew. Make sure a biosecurity audit covers all these activities, as well.

Truck washes

Kettelkamp has performed truck-wash audits that include environmental sampling to look for pathogen transfer.

“For truck washes, it’s best to use high-pressure and hot water as well as a large volume to remove the manure,” sha said. “It’s important to follow-up by applying a disinfectant to the entire surface of the truck.

“Common areas missed are ceilings on any decking in the trailer and tight corners in hard-to-reach areas. Keeping truck cabs clean, whether vacuuming or using disinfectants also shouldn’t be ignored.”

Kettelkamp also has seen problems with load-out chutes on farms. These areas need disinfecting.

While people errors continue to be a major cause of biosecurity breaches, audits will help reduce those slip-ups.

“Make sure audits are in place and we do what we say we are doing and pick up on any area of improvement before we have a disease outbreak,” she said.

“Biosecurity audits are tedious, and they should be. It’s a good thing to be careful.”


Weaned-pig market heats up after PRRS 1-4-4 outbreaks

A strong weaned-pig market this summer indicates the magnitude of the porcine reproductive and respiratory syndrome (PRRS) 1-4-4 variant outbreak in the US pork industry.

“There’s been enough PRRS breaks and death loss that people have to buy weaned pigs to fill their barns and contract obligations,” reported Ryan Strobel, DVM, Swine Vet Center. “When we see weaned pigs still being sold in the middle of the summer for $45 to $50, it shows there’s demand and people are having health problems with their flows.”

When disease affects markets

On rare occasions, disease outbreaks become severe enough to move hog markets. For example, the porcine epidemic diarrhea (PED) outbreak in 2014 and porcine circovirus in the mid-2000s both impacted hog numbers enough to change markets, Strobel said.

Will the PRRS variant impact US markets this fall and winter? While he stressed he isn’t a market analyst, Strobel said the PRRS variant’s impact on hog farms in May and June led him to believe markets in December and January could be abnormal.

“Given the amount of spikes and outbreaks we had, PRRS 1-4-4 could be a market mover,” he said. “It will be interesting to see what the numbers come in at this winter with higher demand than normal.”

Weaned-pig buying advice

The hot weaned-pig market means it can be challenging to find and buy healthy pigs.

“Make sure you do due diligence when purchasing weaned pigs,” he explained. “There are a lot of mistakes made when buying open-market pigs.”

Strobel suggested producers learn as much detail as possible about the health of the weaned pigs before buying. Be sure to ask questions about the major diseases like PRRS, PED and Mycoplasma and follow-up on other diseases like Escherichia coli and Streptococcus suis. He also recommended asking for references from other growers or the owners of previous groups of pigs.

“The PRRS 1-4-4 impact has also left more open contract-grower barns, especially compared to last year when there were no barns available,” he added.

Lessening the impact

With the current market climate, Strobel believes this is a good time to consider hedging for risk protection. “Despite what the numbers say or how optimistic we are, it’s good to manage risk,” he said. “Protecting a certain portion of your production is always a good idea.”

He also thinks this is a good time to reevaluate vaccine programs, especially with all the health challenges facing pigs. “More people are relooking at vaccination programs, whether going to a full dose or readjusting how they give vaccines or the timing,” he said.

“What we did a year ago is obviously different from what we are doing today,” Strobel added. “It’s crazy to think a year ago you could buy a weaned pig for free or $5, and now they are $50.”

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.”


Dry fog with common disinfectants decontaminates supply rooms

Hog producers discouraged to learn foggers don’t fully disinfect a supply room should not close the door on the biosecurity method yet.

New research spearheaded by Erin Kettelkamp, DVM, with Swine Vet Center, found a better solution for disinfecting supplies in a hog facility.

“In previous research, all commercial foggers resulted in incomplete disinfectant contact to all sides of objects,” reported Kettelkamp, who earned her DVM from the University of Illinois. While at the university, she studied fogger decontamination efficacy and identified a new protocol for disinfection.

Particle size, disinfectants studied

Kettelkamp’s research considered two questions. The first was how the aerosol particle size impacted fumigation. The second question was the composition of the disinfectant.

“First, particle size does matter and the smaller the better,” she said. “We used a dry fog that is a particle under 10 microns. A fine mist is 100 microns, so this is a particle you can’t quite see. But when you have them in a high frequency, it creates a dense fog, which is important because those small particles move through the room. Instead of bursting at the first surface they come into contact with, the particles permeate the room and achieve disinfection.”

For the second question, Kettelkamp tested a combination of hydrogen peroxide and peracetic acid, which is used in food processing, dairy and beverage industries for disinfection. After testing different concentrations of both, she found one that inactivated pathogens.

“There is a ready-to-use formula…but it wasn’t strong enough,” she said. “We increased our concentration by doubling our hydrogen peroxide and quadrupling our peracetic acid.”

She also tested using hydrogen peroxide alone at the high rate, but it was not effective. Disinfection depends on peracetic acid in the mixture, she added.

Kettelkamp used a geobacillus indicator strip with a robust bacterial pathogen colony to test the results. She validated the results with a porcine reproductive and respiratory syndrome (PRRS) modified live virus vaccine and manure. The dry fog inactivated the indicator strip and PRRS while also disinfecting the manure.

Dry fog best

“If a producer wants to continue to use a fogging chamber, I recommend working with a veterinarian on using a type of fogger to decrease the particle size,” Kettelkamp said. “Hurricane foggers can be adjusted to smaller particle sizes and will be more effective (than larger sizes).

“The gold standard is a dry fog for best permeation throughout the room,” she added. “Specifically in this model, the hydrogen peroxide and peracetic acid worked well.”

Another benefit to a dry-fog system is it only needs an air compressor for operation. And after treatment, clean-up is easy because dry fog produces no residue or liquid pools that need to be cleaned up.


Based on her research, Kettelkamp reports complete disinfection by aerosol decontamination occurs with droplet sizes less than 14 microns. Optimal results require a droplet size that’s less than 6 microns, also considered a dry fog.

In addition, the disinfectant concentrations for decontamination must be hydrogen peroxide levels above 4.2 ppm and peracetic acid levels at 0.13 ppm.

“Fogging certainly isn’t the only method to decontaminate items as they come into farms,” she added. “Other methods such as hand spraying items and time and temperature to let items decontaminate are also effective. Fogging could also be used with other methods to achieve a really robust decontamination.”

For more information, you can view Kettelkamp’s research presented at the 2021 American Association of Swine Veterinarians meeting here:

Nasty PRRS variant continues to spread undeterred by summer’s heat

The virulent porcine reproductive and respiratory syndrome (PRRS) variant identified as PRRS 1-4-4 continues its destructive march through hog farms, even in the heat of summer.

The PRRS variant first struck herds in Minnesota and northern Iowa this past winter, and while producers and veterinarians hoped it would calm down in warm weather, latest data suggests things aren’t so simple.

“Even when it was 99°, we were getting calls about PRRS breaks,” reported Laura Bruner, DVM, with Swine Vet Center in St. Peter, Minnesota.

“It’s unprecedented; it’s unusual,” she continued. “This virus is walking past normal biosecurity practices such as on-farm biosecurity, trucking biosecurity, air filtration and feed mitigation.”

Survey shows variant’s hot spread

Alarmed by the continued PRRS 1-4-4 outbreaks, Bruner surveyed her peers of 15 veterinarians in the US to understand the variant’s reach. She was shocked by the results.

“In just over a month during the warm time of the year, we had 107,000 sows break with PRRS 1-4-4, and I believe that is an underestimation,” Bruner said.

“When you talk to practitioners about it, they have farms breaking with the variant that have never broke with PRRS before, and for some farms it’s been decades or never.

“Also interesting is how many nursery breaks there are,” she continued. “I can count on both hands in my career how many lateral field infections have happened in the nursery. It has caused more mortality and makes these nursery pigs quite a bit sicker than what we have seen other viruses do in the past.”

Another unusual detail of these outbreaks is the consistency of the PRRS 1-4-4 variant.

“Historically, if you have a sow-farm break, you call another veterinarian and compare sequences,” Bruner explained. “Rarely do they match. But with this one, it’s frequently over 99% to 100% a match. I had one farm in southern Minnesota that was a 100% match to a PRRS virus in northern Minnesota.”

Time to collaborate

Armed with her PRRS 1-4-4 survey results, Bruner sought help from Cesar Corzo, DVM, at the University of Minnesota. Corzo works with the Morrison Swine Health Monitoring Project, which monitors the incidence of swine disease such as PRRS. He set up a meeting at World Pork Expo (WPX) with other veterinarians and swine disease researchers to discuss the PRRS variant.

“My purpose of getting that meeting together was to collaborate and learn from each other,” Bruner said.

“We’ve learned we don’t know everything about PRRS, and specifically this virus because it does seem to be different. It is a game changer, just like PED (porcine epidemic diarrhea) when it arrived.”

Bruner hopes new research discussed during the WPX meeting will shed light on the variant’s unusual virulence. But for now, collaboration among practitioners will help fill in answers.

“We need to learn from who breaks with 1-4-4 and who doesn’t,” she said. “And we need to learn the successes and failures of their investigations.

“We need to go all the way back to the beginning and ask: Do our normal biosecurity practices work? Does our normal disinfection work? Do the filters we use today work? What’s different?”

Tighten biosecurity

With the variant’s threat to hog farms, Bruner recommends producers use this as an opportunity to improve biosecurity on the farm.

“Take a hard look at your biosecurity for any weaknesses and get them corrected,” she said. “We need to be looking at all the major inputs into the farm like people, feed, water and air as a source of infection.

“We are unsure of feed as a route of entry and haven’t done research on PRRS specifically in feed. I think it is worth considering a feed mitigant for sow farms and gilt-development units. We know that there are ingredients that provide a better environment for virus survivability than others and those need to be investigated.”

For farms that broke with PRRS 1-4-4 last winter, Bruner said it is still too early to know if the virus leaves the farm or if it will be difficult to eradicate.

For more information about PRRS 1-4-4, visit:

Highly infectious PRRS variant causes high mortalities on sow farms

New PRRS 1-4-4 L1C variant presents dramatic symptoms, quick spread

Virulent PRRS outbreaks in grow-finish require fast action to cut losses