Early gestation is a critical and often overlooked period in the reproductive process.

Here’s the thing, once insemination occurs the embryo is free-floating for about 13 to 14 days until it begins to attach to the uterus. That’s why it’s so essential to handle bred sows and gilts with care during that period. 

“If you don’t take precautionary steps during early gestation, you might not lose the whole pregnancy, but litter size can decline or the pigs could be smaller at birth,” says Jodi Sterle, swine reproductive specialist at TexasA&MUniversity.

The period immediately after insemination is the critical time when semen moves through the reproductive tract. This allows fertilization to occur in the oviduct sometime between when ovulation occurs up to two hours after breeding.

After that, the embryos are free-floating in the uterus. At days 10 to 12 of pregnancy, the embryos undergo rapid elongation where they go from a millimeter in size to an elongated embryo many millimeters in length. This also is the time when embryos use hormones to signal the sow or gilt of their presence. On days 13 to 15, the elongated embryos form a loose attachment to the uterus. They then begin to grow and get nutrients from the sow.

Another key period begins around the 18th day after fertilization. That’s when the uterus and membranes associated with the embryos take on fluid. During the third week, the embryos form fetuses and defined placental membranes. At this point, there can be another period of embryonic loss, notes Sterle. However, researchers still don’t know if that’s because the embryos are sensitive to pH or hormonal changes that occur, or if it’s due to stress.

With so many critical events happening in a short timeframe, you certainly need to focus on sow/gilt handling and care. Sterle and Rob Knox, swine reproductive specialist, University of Illinois, offer a few tips to help.

  • The breeding schedule depends on the estrus detection frequency.
  • Once a day: Breed sows once every 24 hours as long as they remain in standing heat. Gilts should be bred when they are discovered in standing heat or within 12 hours of detection.
  • Twice a day: Breed sows when they are discovered in standing heat or within 12 hours of detection.
  • Many production systems require that sows and gilts are moved into groups after insemination. Ideally, it’s best to not move these females at all, but for many systems that’s an unlikely scenario. You should wait at least 24 to 48 hours to give the sperm time to move through the reproductive tract.

When you move sows try to minimize their stress. If temperatures are high, move sows during a cooler part of the day to prevent heat stress. Sows and gilts that are heat-stressed during the first seven days after insemination are shown to have severely limited litter size, embryo survival and conception rates.

Also, during the actual moving process eliminate shadows and foreign objects in alleys, don’t use electric prods and ensure that floors are not slippery. The point is to limit stress during any moving process. (See sidebar for tips on moving sows.)

  • Make sure the production system or animal group is managed well. Sows housed in stalls don’t face the risk of fighting or running around. Animal groups that are used to being housed together and remain together should be fine following the insemination process. The key is that you don’t transport females to another farm or mix them into a new group where they will fight or risk injury.
  • Another strategy is to avoid vaccinations that could potentially spike a fever. Knox points out that it can be harmful and stressful to vaccinate a sow during the first 18 days after breeding because it’s a critical period for embryonic survival.
  • Don’t overfeed the sows and gilts. “Try not to feed more than 4 to 5 pounds of feed during the first three days after breeding,” says Knox. “Information out of Canada indicates that overfeeding young females during the first three days can reduce embryonic survival. Overfeeding alters progesterone circulation, and could detrimentally impact embryo survival during the early weeks of pregnancy.”

A general rule for feeding during gestation is 4 pounds a day of a balanced diet, says Sterle. More feed is required for growing gilts as well as during cold weather.

It’s important to maximize a sow’s feed intake during the first seven to 10 days of lactation to properly establish lactation hormones. For the first few days after farrowing, feed a sow as much as it will consume in about an hour. Make whatever adjustments are needed at the next feeding to maximize intake and keep feed fresh. Most sows consume 10 to 12 pounds of feed a day during peak lactation.

If you have a high farrowing rate or litter size, don’t mess with the system, says Knox. “But if you are having problems, that’s when you need to look at making some changes in specific areas.”

There’s no guarantee or data to say these tips will increase your pigs per litter by say, 1 or 1.5 pigs, but even improvements in the sows’ attitudes or health status is beneficial.

Another factor to consider is late-returners— these are sows that return to heat around 24 days after breeding. These sows were pregnant but lost the litter or they didn’t get pregnant but returned to estrus at a later time.

“We don’t know how many piglets are lost in early gestation, we’d have to totally interrupt pregnancies to get an idea,” says Sterle. “The focus is more about management practices to keep the sow comfortable and de-stressed during this early critical time frame.”

In reality, you may lose only a few pigs in any given group, but even two pigs out of 200 makes a difference.

“It wouldn’t cost a producer much to apply management practices to address sows’ needs during early gestation,” says Sterle, “and sow comfort alone is worth it.” n

Slow and Gentle

Moving bred sows and gilts while embryonic development is occurring can be stressful for you and the animals. It can ultimately impact your herd’s productivity.

To make any sow-handling process run smoother, Rob Knox, swine reproductive specialist, University of Illinois, offers these tips.

  • Be patient. Remember that you are moving a large animal through a narrow space. Take your time and move each sow individually. Focus on the individual animal’s reaction, and adapt your process accordingly.
  • Move an individual sow at a slow pace. Also, plan to move the animal for only a short distance.
  • Make sure all areas of the facility are well lit. Certainly that’s to allow you to see clearly, but also to give the sow a well-lit viewpoint. 
  • Check the alleyways to ensure there are no slippery patches on the floor. Also see that the there are no sharp objects that could affect the sow along the path.
  • Before moving a sow, check that the feeder and waterer in its new housing location are working properly. Of course, a gestating sow needs adequate levels of feed and water. This is especially critical in trough– water systems.
  • Remove leftover feed and clean out feeders and waterers every day.
  • Make sure flooring in the gestating sow’s stall or pen is safe and that it doesn’t need repair.
  • Make sure the area that sows are being moved to is dry and has adequate lighting and temperature control to avoid chilling or overheating the sows during the day and at night.
  • Check that the fans and ventilation system are working properly.