Combat seasonal infertility with strong husbandry

Seasonal infertility continues to be a widespread problem for sow herds across the US. And if you don’t have a problem with seasonal infertility, it may mean you are not recognizing it, reported Daniel Gascho, DVM, with the Four Star Veterinary Service office in Mexico, Indiana.

Gascho offers several suggestions for recognizing and dealing with seasonal drops in fertility that occur in late summer and early fall but may not be noticed until winter.

“The signs can range from the obvious of just a lot of sows and gilts are not pregnant and I don’t know why,” he said. “But for people focused on breeding, they may notice delayed return to heat after weaning. You may notice, when they do cycle again, that it’s at an unusual time and not on a normal 21-day cycle. Or you may notice she was pregnant and then she lost it.”

Causes for seasonal issues

Many factors are involved in seasonal infertility. Top of the list is hot weather when sows don’t like to eat or breed, according to Gascho.

Another big factor is poor nutrition caused by mycotoxins or poor corn quality. “We sometimes jokingly refer to it as ‘combine-itis’ because people working in the fields this time of year are busy, and general husbandry drops a bit,” he explained. “They are not paying as close attention to the things that play a role in infertility.”

Other stressors can cause infertility problems like moving sows too quickly after breeding, crowding or fighting in gestation pens, and not pushing feed intake while sows are nursing piglets.

“But you could have a perfect farm, and you’re still going to see a drop in fertility this time of year,” he added. “That’s the part we don’t fully understand. A lot of people suspect it has to do with natural hereditary instinct of swine where wild pigs quit breeding in September so they don’t have litters during the winter.

“Our commercial animals aren’t affected by temperatures, but some scientists hypothesize it has to do with photosensitivity — the length of the day.”

Strategies to manage infertility

Regardless of the cause, producers can follow management strategies to minimize the seasonal infertility issues.

Because heat is the leading cause of infertility, Gascho recommends using cool cells, misters and ventilation rates to keep ambient temperatures low and sows comfortable. This equipment also must be checked regularly to make sure it is working.

“When sows are too hot, they don’t feel like eating, which makes them not maintain their weight, which makes them not breed well,” he said.

Reduce feed issues by paying attention to quality, especially in the fall when last year’s crop has been stretched to cover until the new crop is harvested. That’s when Gascho sees a spike in feed-related issues like mycotoxins, mold contamination, odor, lower quality and poor nutrition.

Keep sows healthy by providing adequate feed. “Make sure you’re pushing feed intake during stressful times in their lives when they are nursing piglets or you are trying to get them to ovulate,” he added.

To help manage infertility problems, Gascho suggested, “Heat checking twice a day to find [females] that are not bred. Sort them out and get them rebred. This may require ultrasound to check for pregnancy at 4 weeks if that’s appropriate for your farm.”

Focus on animal husbandry

In addition, Gascho recommends closely following good husbandry practices to reduce infertility issues.

“We just have to focus extra hard and make sure we do all of the things that we can control exactly right so we don’t have that on top of this seasonal or inherent thing that always happens,” he said. “Don’t get discouraged because everybody fights this.

“The best way to manage it is to find [unbred females] right away and do something about it so they don’t disappear into your herd and 3 months later, half of them aren’t pregnant.”


Check with your Four Star veterinarian to investigate seasonal infertility at your farm.


Well-managed estrus helps gilts, sows achieve top performance

Success in pork production starts with a well-managed sow herd that cycles together and on time. Unfortunately, reproductive problems can derail the breeding process.

“One of the biggest [challenges] we battle is making sure we get these gilts cycling and breeding appropriately,” said Daniel Hendrickson, DVM, Four Star Veterinary Service in Farmland, Indiana. “It’s very, very important that we get these gilts off to a good start and get them bred in the herd.”

A successful first parity sets gilts up for successful parities throughout their lifetime, Hendrickson added.

Getting gilts bred

The main reason gilts do not get bred on time is lack of good boar exposure, according to Hendrickson. Boar exposure should start in the gilt-development unit and continue when they enter the sow farm.

“Make sure not only are gilts getting more exposure, but multiple boar exposures,” he explained. “Gilts react differently to different boars because different boars put off different amounts of pheromone.

“And sometimes it takes getting those boars in with the gilts…You’re not going to get very good exposure if you don’t actually get that boar into the pen and let him get in contact with the female.

“Also, gilts [should be] at adequate size, adequate age, adequate body condition. All those things can affect estrus.”

Hendrickson wants gilts bred at 36 to 38 weeks of age and farrow at 1 year of age. He also wants gilts weighing at least 300 pounds. “We want them old enough and big enough so when they do farrow…there are fewer dystocia problems,” he said.

Sow challenges

In sows, Hendrickson sees some seasonal influences on breeding. In late summer, there can be an uptick in sows with delayed estrus. Instead of coming into heat at 5 days post-weaning, they come into heat 6, 7 or 8 days post-weaning. In the winter, he notices another delay in estrus due to the cold weather.

“I believe the main [problem] that affects sows coming out of farrowing is body condition,” he said. “If they go into the farrowing house too skinny, then they come out of the farrowing house too thin. Then the sow’s body goes into a protective mechanism where they know they’re not in good enough condition to cycle like they need to.”

When sows and gilts do not come into heat, Hendrickson said to look for the cause in genetics, management and boar exposure. If the cause is not apparent, then he uses estrus manipulation products.

How to manipulate estrus

“Our ideal situation is to use our hormones or injectables, P.G. 600 and Matrix, at a bare minimum,” he said. But if the cause for estrus delay is not found, then he will use a product to get females in heat and bred.

“The only time P.G. 600 is successful is when a gilt’s either been cycling and quit cycling through her estrus, or she’s never cycled before,” he explained. “That’s when we can use P.G. 600 to stimulate that gilt to cycle that first time and then go from there.”

But if a gilt cycled 7 days ago and the breeding crew missed it, or the gilt didn’t have a very strong heat, P.G. 600 will not change the cycle or help it.

“An example of how I suggest my clients use P.G. 600 is once we definitely know those gilts are of age and the right size, we really stimulate them with multiple boars…for 4-, 5- and even 6-week period…Then we’ll go in and use P.G. 600 to help stimulate those gilts that haven’t cycled within that first window.”

Matrix is a product Hendrickson uses to help organize a group of sows or gilts for possibly batch farrowing or a breeding project. The product delays estrus and works well on females that have been cycling, he added.

To organize a group of gilts where some have and some have not been cycling, he suggested putting the group on Matrix or a progesterone product for 14 days. On the last day or after the last dose, he gives the gilts a dose of P.G. 600. This results in a high percentage of gilts coming into estrus together.


Better manage your sow herd with uniform body-condition technique

After noticing an alarming difference in sow body conditions in several herds, Cary Sexton, DVM, Four Star Veterinary Service (FSVS), became concerned.

“I saw people that were highly subjective in their ideal animal body conditions,” he said. “On farms with multiple employees who evaluate sows, I saw a lot of group-to-group variability among sow groups in crated gestation. Pen gestation was even more variable.”

The variability among sows was especially concerning because feed budgets are based on sow condition, explained Sexton who is with the FSVS Kinston, North Carolina office. If the herd isn’t uniform, then some sows eat too much feed, and others don’t get enough.

The solution

Sexton looked at different ways to objectively determine sow body condition. Most were eliminated including ultrasound and fat-depth measurements, which requires a high level of technical skill.

He decided to focus on a sow caliper designed by Mark Knauer, PhD, swine specialist at North Carolina State University Extension. Knauer agreed to meet with Sexton and some pork producers to discuss the caliper.

Knauer designed the sow caliper to standardize sow body condition instead of relying on visual scores, which can lead to expensive herd problems. Underfed sows more frequently experience impaired reproduction and well-being issues. Overfeeding sows leads to higher feed costs, more farrowing problems and higher pre-weaning mortality.

Implementing sow caliper

The sow caliper is a sturdy metal device that’s designed for easy use on sows. After Knauer demonstrated the caliper, Sexton said producers were supportive about trying it in their herds. Employees were less supportive, with concern about how long it would take to measure sows with the caliper.

“But once they used it, the employees felt they were doing a better job determining body condition than previously,” Sexton said. “And most employees can do it in about the same time as they previously were taking in performing visual scoring.”

The caliper must be used properly to accurately determine body condition. Sexton said the caliper must be placed at the last rib and with the pivot point on the spine for proper calibration.


He recommends checking sows with the caliper at breeding, pregnancy check at 50 to 60 days, and at 90 days. Gilts can be started at pregnancy check or after to prevent interfering with conception. It can also be used in a gestation pen system if the animals are housed in crates until pregnancy check or beyond.

“The first few weeks of pregnancy are the cheapest time to recover condition lost during lactation as the sows have less nutritional demand from the next litter,” Sexton said. “The condition can also be carried over into the gestation pens in assigning them and being able to more closely manage the amount offered each animal.”

$250,000 feed savings

Some of Sexton’s clients have used the sow caliper for several years. The biggest change for them was sow feed management.

“We saw huge feed savings for some companies, and one system saved $250,000 a year,” he said. “For a few systems where the sows tended to be thinner, there was a feed increase but with better management and feed utilization.”

Sexton said his biggest surprise was seeing how the small differences between body conditions can cause big variabilities in the animal. For example, he’s noticed sows in good body condition with adequate nutrition will handle disease challenges better.

Another benefit of well-conditioned sows is more piglets born live at the second and third farrowings, he said. The sows also continue to hold the higher numbers in subsequent farrowings.

Employees regularly using the sow caliper also observe sows more frequently. Health issues like lameness can be caught early and addressed before growing into major health problems, Sexton added.

For more information on the sow caliper, contact Mark Knauer.