If you are squeamish, pig breeding is not for you! I have included anatomical pictures in this post to help visualize breeding, heat, and changes during gestation. You will want to be very familiar with your pigs baseline anatomy so you can notice changes. It is as easy as taking a glance once a day while you are feeding – once you know what you are looking for of course.
In the world of pigs, we talk about “Gilts” (females that have not yet had piglets), “Sows” (females that have had piglets), “Boars” (intact males), and “Barrows” (altered males that have had their testicles removed). When they are weaned as piglets, you will often see gilts, boars, and barrows advertised as “Weaners” as in they have just been weaned–not to be confused with the sometimes used but nevertheless incorrect homophone “Weiners”, as in the sausage.
Gilts and boars begin to mature around 8 months (as early as 5 months for some lines). While boars may start breeding around this time, they don’t become fully fertile until about 12-18 months. In addition, while gilts begin to cycle at around 8 months old (on average), it is best to wait until they are 12 months old when their body is more mature (do not leave it much past 18 months). The New Zealand Kunekune Association has great baseline information on breeding and infertility. An important note from their website is that if you wait too long to breed a gilt, she may have difficulty catching or if you leave a sow too long between pregnancies, she may also have difficulty catching.
It is advised that pairings are made between comparable-sized pigs. Breeding a 200lb Kunekune gilt to a 500lb Berkshire boar could cause serious injury to the gilt and possibly leave her lame. Likewise, breeding a small boar to a large gilt may result in the boar not being able to reach his target and becoming frustrated or possibly giving up all together. That being said… (see picture)
It is also important to separate boars and gilts from each other by six months of age so they don’t create familiar relationships and stop to see each other as breeding partners and to prevent a gilt from being bred too early. It is best to keep them separate unless they are temporarily together for breeding. To maintain optimum fertility is also important to not wait too long to breed, too long in between pregnancies, or allow gilts/sows to get under/overweight. Pigs are most fertile when kept regularly pregnant and in good body condition. Waiting approximately more than 18 months to breed a gilt, going over a year between breeding’s, or keeping a gilt/sow overweight can decrease fertility and lead to cystic ovaries and/or decreased uterine tone, stopping their reproductive cycle prematurely.
Make sure all your gilts/sows and boars shots are up to date before you breed them. It is important they are in good health and protected from reproductive disease before you breed them. Some vaccines like Circoflex should not be avoided during pregnancy (especially final stages) and some are intended to be given right before breeding so it is important to make sure you are up to date before you breed.
When it is time, we introduce a boar to a gilt/sow, we generally do so on neutral ground. If the boar is inexperienced we may even move the sow to his area to him a bit more confidence. Breedings can be done just during heat cycles, but we tend to leave the boar and gilt/sow together for two heat cycles to make sure she has caught – especially if it is difficult to see her cycles.
If you do not see the actual breeding, signs include discharge around the boar’s sheath/belly, disturbances to the gilts/sows hair where the boar would have been mounted, discharge leaking from the gilts/sows vulva, or a sperm plug (looks like a lump of clear snot) on the ground.
You will know a gilt is bred when she does not cycle 21 days after breeding or have a vet confirm with an ultrasound.
Gestation is approximately 116 days long (two days longer than average pigs). Some of our sows will even go as long as 117-124 days. There can be a bit of variation depending on how many days she stood for the boar, implantation and the length of the heat. If you notice a heat cycle and witness breeding, mark your calendar for 21 days and 116-124 days. If you don’t see another heat cycle at the 21-day mark, get ready to prepare for a litter of piglets – she is “in pig” (fancy talk for being pregnant).
Starting around 8 months, gilts will begin to cycle about every 21 days (every 21 days like clockwork on our farm). Heat cycles last from 8 hours to 4 days (we typically observe 1-2 days). You will notice swelling in their vulva from increased blood flow, this often makes the area pinker. Each gilt/sow will look a little different. The key is to know what their “normal” looks like for her and keep an eye out for changes. Gilts can be more subtle in their changes than sows and lighter-coloured pigs are easier to see colour changes on.
This is “normal” for these three pigs. None of them are in heat. Their vulvas are not pink, swollen, or elongated. Those physical changes happen during a heat cycle or to a larger extent, a few weeks away from farrowing. Notice that pinkness is easier to detect on lighter pigs? On darker pigs, you mostly rely on swelling to detect a heat cycle.
Here are the same three pigs in heat. Overall, you will notice the vulva swells, elongates, and turns a little pink. The colour change is less noticeable is the last gilt, the shape change is hard to miss though.
In addition to physical changes, you may notice behavioural changes – especially in their vocalizations and desire to stand for boars. A gilt/sow not in heat will not typically tolerate boars mounting her. A gilt/sow will stand for a boar (or any pressure on her rump) when she is ready to be bred, this is called “Standing Heat“.
Alright, this is the resource I wish I had when I started with pigs. To illustrate the changes during a pig’s gestation, I followed our gilt Sandy (GVF Haunene 1) to document the changes in her body during her first pregnancy. She is cream-coloured so it is easier to see her changes than on a different patterned or coloured pig. Each pig is a bit different in its presentation, so you need to get to know what “normal” is for your gilt/sow. Once you have a baseline, keep an eye out for changes to their vulva, teats/milk line, body shape, and behaviours. First-timer gilts can be very hard to detect changes in, whereas an experienced sow often has more obvious signs of heat and pregnancy progression. The changes seen in Sandy here will accelerate and become a bit more accentuated in future gestations.
A gilts/sows vulva will begin to swell and become pinker as their due date approaches. Sandy started showing changes (swelling) around 3-4 weeks before farrowing (pictured at 96 days gestation). This first change is easy to mistake as a heat cycle in absence of other signs of pregnancy or mistake as her being at term if you didn’t see the breeding. She had another major change (more swelling) at 115 days gestation. Her anatomy has to change in order to squeeze out 2-3lb piglets, so elongation and elargment of her vulva is important. Her vulva will return to normal in the weeks after farrowing.
INCLIDE BASELINE PICTURE
Teat changes (milk lines) are the most obvious difference between a gilt and a sow. A gilt can have an almost unnoticeable change through her entire gestation with just subtle changes to her milk line towards the end. An experienced sow will bag up and have noticeable mammary enlargement sooner. As you can see, Sandy’s line looks like it did prior to pregnancy all the way to a week prior to farrowing. On day 113 you can see on her back left teat, just the slightest hint of mammary enlargement (“bagging up”). At 115 days, just one day before her due date, the changes are still subtle, whereas a sow would show obvious signs of mammary enlargement.
It may or may not work (pigs choose to let down their milk), but if you squeeze the mammary gland (like milking a goat/cow) and get some milk, she is in active labour and you should have piglets in the next 24 hours. I have had this work for me but I have also not got milk using the same method and had a litter within 24 hours so don’t assume there won’t be piglets if you don’t get milk. You can pretty much guarantee their imminent arrival if you do get milk though.
It can also be a bit more difficult to see the baby bump develop in a gilt versus a sow. Litter size and the weight and length of your gilt/sow will also dictate how big of a bump you see. We breed for long sows with lots of room for large litters of babies so I often find myself second guessing if she is still “in pig”.
Here you can see Sandy on her first parity at 96 and 115 days gestation. Cedar pictured on the right is on her third parity at just 83 days she is much bigger than Sandy. Sandy is 16 months and Cedar is fully grown at 3 years old here. Even though Cedar is a couple of inches longer, Sandy hides 12 piglets better than Cedar’s 10. I usually see litters average around 7 piglets – 10 and 12 are very respectable litters.
Between piglets, placenta and increased blood volume, getting around when “in pig” is hard work. I often notice even starting halfway through a pregnancy that gilts/sows begin to slow down. They sleep more, hang out near the shelter more (even when the rest of the herd takes off to graze) and prefers to sit instead of stand.
Around the day of the delivery, the gilt/sow will begin to build a nest – a sign that babies are very close. When active labour begins she may begin to bite down on things, the crush rails in our stalls have bite marks for this reason. It only seems to happen when they are in active labour and unsettled. In the hours before farrowing, she may go from tired and lethargic to chompy, nesty, fidgety, and purposeful.
“Farrowing” is fancy pig talk for giving birth. Some breeders allow their pigs to farrow on pasture but most still use a farrowing stall (not a crate!) to facilitate the farrowing process and keep piglets out of the elements for at least the first few days. A week prior to farrowing, you should start to see the changes we discussed above: swelling of the vulva, the development of a milk line, an obvious bump, and behavioural changes.
What you may need:
- Private area (like a stall or small barn) about 8’x10′ for the sow
- She won’t be terribly active post-partum and this is plenty of space
- Crush rails along the walls so piglets are protected
- The middle of the board should be about half the height of the sow
- Warm creep area (possibly with a modified barrel with Premier 1 heat lamp)
- Protect it with at least two boards so mom can’t move it or get it out
- 250W bulbs (red or white) are great most of the year, and 125-175W bulbs for the summer. For extreme winter, a Premier1 600W Carbon may be more appropriate. Here on the coast, we stick with a 125W or 250W bulb.
- Piglets that have wandered away from mom too long or from their heat lamp may become chilled. A chilled piglet won’t nurse so make sure it is warm, use a portable heater (safely and only while you are there) to warm them up enough to nurse if it is particularly frigid. Getting the creep/barrel to 25-27°C for them to retreat to when not nursing is a good safeguard.
- Farrowing Kit
- Rubber water dish for mom – only filled with a bit of water so piglets don’t fall in and drown
- Heat gun to check the temperature of creep/barrel (25-27°C)
- Towels to dry piglets (often we skip this step)
- Iodine for umbilical cords (we’ve had equal luck thus far with or without iodine)
- Scissors for cutting the umbilical cord (we just let them fall off on their own unless they are tripping over them)
- Injectable Metacam (pain drugs) if she is in pain/distress after the birth
- Calf Choice Total Colostrum Gold (only if necessary and you can freeze any unused powder to keep it longer and use again). We have always been advised against using lamb or goat colostrum
- Milk replacer (piglet or goat)
About two weeks prior to farrowing, I separate my sows and let her get accustomed to her new digs. I prefer something close to a 8′ x 10′ stall with crush rails installed along the walls with access to outside as well as a smaller ~16′ x 32′ grassy area (what I call a nursery paddock – conveniently the size of 6 hog panels). It is big enough that the sow can graze but not so big that we lose track of piglets. If the area gets overgrazed, we supplement with hay, or gradually extend the area to give more pasture access.
I provide a layer of shavings in the stall for bedding and absorption, and then a flake of straw for the gilt/sow to nest with. When the pasture is poor quality, I’ll give her a flake of hay to eat too if she isn’t just using it to make a deeper nest.
In the corner, I provide a warm creep that is boarded off so the sow can’t get through or under. The creep is a warm spot (25-27°C) where piglets can get snuggle up in a warm area away from their mom if they want. I’ll switch out the bulbs between a 125W or 250W bulb to get the temperature right and use a barrel in colder weather to keep the heat concentrated if needed. During the summer I don’t use a heat lamp at all except for maybe the first 24 hours in case a piglet wanders off to a corner, gets lost, cools down, and needs warming up. If summer heat gets excessive (30+), I will trade out the hang a fan instead of a heat lamp to keep things circulating. I’ve gone as far as giving piglets a dunk up to their shoulders in a bucket to cool them off in the late afternoon on hot 30+ days if they are very young and struggling to regulate their heat (panting). They don’t like getting cooled off or misted, but it stops them from panting and dehydrating themselves excessively.
In the winter, when we use them, we use food-grade barrels and Premier1 heating as these pose less risk of fire than other setups. We concurrently hook up a networked smoke alarm in the barn whenever we have heat lamps in use. I would never lock up an animal with a heat lamp, that is too much of a safety risk. While we always offer heat at first, we give the sows/litter the option to use it or not. Some sows/litters won’t use them, even in the dead of winter. We choose not to force it and let the pigs decide. Our farrowing philosophy is to use the least amount of intervention possible. If we use the heat lamp/barrel for nothing else, it is always good to have it on during the early hours of the birth in case a piglet wanders off to a corner during labour and gets chilled. It is super handy to have a warm spot to heat them up so they can nurse. Maternal disposition, maternal experience, and weather all factor into if the lamps actually get used or not. We have had gilts and sows farrow on the other side of the stall from the lamp in -5 degrees Celcius with no losses, they had the option and chose not to use it. I am not advocating for no heat, but I want to be candid about our experiences. The sow’s comfort is important to us and as long as she is doing her job, we let them do it their way.
Bedding is important for nesting, but if it is too deep the piglets have a hard time getting out of the way. We tend to use shavings with a bit of straw on top. Crush rails are protrusions along the walls to prevent mom from laying down against the wall and inadvertently crushing a piglet. The crush rails help until moms and piglets sort out that the middle of the stall is the best place to lay down and nurse so they don’t get stuck against a wall trying to get out of the way. Usually after the first parity (that is the first time a gilt has a litter) and the first couple of days they have that all sorted out.
When the time comes, we expect our sows to birth mostly or entirely unassisted. Although we may towel off her piglets when she is done and monitor her and her piglets for signs of distress in case intervention is necessary. We stand back and talk very little so the maternal bond is disrupted as little as possible by human interaction and handling. In most cases, we try to just check in using a barn camera to be as minimally intrusive as possible. Maternal instincts and ease of birth are hereditary and are traits we select for. A careful sow will get up and down slowly and chatter to her piglets as she does so.
Some pigs stay down the entire birth, others jump up and spin around for each one. One of our sows had 8 piglets, insisted on standing at the gate for dinner, ate dinner, and then went back to have two more piglets. If a sow is getting up for each piglet, we may quietly move each piglet over to the creep until she is done. You will know she is done when she passes both intact horns of the placenta. Remove the placentas shortly after she delivers them. Some sows will try to eat the placenta. We tend to remove it as it poses a slight choking hazard to the sow. I want to say let her eat it and get the nutrition, but I’ve seen them gag on it and the idea of hand raising a litter and losing a sow overrides my desire to let nature take its course on this one.
If she starts labour and passes at least one piglet, and then stops contracting for more than 45 minutes, our veterinarian suggests using a dose of oxytocin. This must be done carefully and NOT before she passes her first piglet. We recommend only administering oxytocin under veterinarian supervision – find a vet you like well ahead of needing one!
Once done, she will not be terribly active, some pigs will stay down for up to 10-hour stretches, and some will be up a little more often. Birth is exhausting! Feed her as usual and gradually up the feed over the next few days. She gets her usually breakfast and dinner, as well as an extra half serving for each piglet. So if she has 8 piglets she gets her usual serving plus 4 extra adult pigs worth of feed twice a day – pretend you are feeding 5 pigs (1+0.5×8=5). For a litter of 6, she would get 4 pigs worth of food (1+0.5×6=4)
We feed our sows outside the stall for the first few days as some refuse to soil their stall and they can eat and poop in peace outside for a few minutes before going back in. It also prevents piglets from getting trampled while mom is focused on eating rather than her piglets. This routine will vary between each setup–this is just what works for us. We keep a shallow water dish in with mom and one outside for her to use when she eats. The dish must be safe enough and shallow enough so piglets don’t wander in and drown in it.
While the sow eats, I do general health tasks like weights and shots. I also look for things like scours (yellow runny poop), eye infections, injuries, or anything else out of the usual. Early intervention is key if a piglet is in distress. If everyone is healthy and eating, we stay out of the way. Although I have been known to trim an umbilical cord to ground length if it is so long that it is causing drag for the piglet and its tripping over it.
Tracking weights helps us calculate piglet rate of gain (ROG), make sure all the piglets are making healthy gains and track herd/litter trends. We weigh on days 1 & 3 and weeks 3 & 8. Newborns are typically 1 to 3lbs. To overgeneralize, 1lb would be small, 1.5 to 2.5 lbs is a good size, and 3lbs is pushing too big (hopefully it didn’t get stuck!). The bigger the litter the smaller the average-sized piglet in my experience, it doesn’t take them long to make up the extra weight though. Piglets may lose weight for the first day or two while they are getting colostrum but will start gaining quickly after that going to 6-10lbs by week 3 and then 15-30lbs by week 8 depending on how much creep feed they are getting or how much food they are stealing from their mom.
Keeping track of them to do weights and shots can be a challenge with a large and similarly coloured litter. Using a livestock crayon or buckets (one for “done” and one for “need to be done”) can be helpful. On day one, I do myself the favour of video recording each piglet and stating the sex, number of teats (left and right), number of wattles, and weight. Then I record them in my spreadsheet with details of their markings so that when I follow up in a few days, I get progressive weights on the right piglets. Having this information recorded also makes litter notifications a breeze. We send out a notification to IKHR for every litter – whether we register them or not. I usually notify within a day or two of the litter being born.
Around three days old we start letting the piglets outside and increase the length of time out for the following week until they are out full-time. The sow will show them how to graze and engage in piggy behaviours – give her the opportunity. This is also the time when they get their first shots. Head over to our herd health LINK TO HERD HEALTH POST post for the worming and vaccine schedule we use as well as notes on how we. troubleshoot piglet issues.
Pastured pigs are on dirt and theoretically don’t need an iron shot, but if they are inside for the first few days in a farrowing stall, they may become lethargic and die from low iron. We don’t take the risk. Selenium is an essential nutrient that is low in our soil and like all livestock in our region, we also make sure they get a vitamin E/selenium shot. A lack of the shot and/or lack of selenium in feed is known to cause Mulberry Heart Disease (MHD), which is fatal.
Piglets will start to eat mom’s food within the first few weeks as well as learn to graze with her, mouthing grass as early as their first week of life. By 8 to 12 weeks, they will be ready to wean. All piglets are tagged at weaning (whether they stay on or farm or leave). Identification is required for registration and for butchering. We find tagging when young is much easier than tagging an adult. We disinfect the ear with rubbing alcohol and crimp the tags towards the base of the right ear between the 2nd and 3rd ear veins. Tags (F18) and the crimping tool can be ordered from your PigTrace account. You need a PigTrace account and premise ID to get tags.
After weaning, a sow will usually go back to heat within a week of weaning. We may occasionally breed back right away but often we breed around every 10 months. We make sure to breed each sow at least once a year and never more than twice a year.
As a reminder, this information reflects my experience, information passed on to me by my mentor and consultations with our farm vet. My experiences may be very different from your own and I am happy to learn from you too. I am always eager to hear from the Kunekune community about both successes and failures.