What You Need to Know Before Choosing a Boar

Choosing a boar to breed to your sows or gilts.  Breeding pigs.

Are you thinking about breeding your pigs?  Do you know what to look for when choosing a boar for breeding purposes?


Well then you've found the right place!

What qualifies as the 'best' is going to be different for everyone based on what they are working towards.  If you purchase a boar (or semen) from a reputable source, you'll have an abundance of information in front of you that may seem overwhelming.

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​But it doesn't have to be!

When you are choosing a boar to breed your gilts or sows to, you want the best.

Reading information about potential boars is pretty straightforward.  I'm going to explain some of the basic terms that you could see used and help you understand what exactly they mean.  This will help you choose the best boar to meet your needs.

You can look at this information when choosing a boar for either natural mating or artificial insemination.  Artificial insemination in pigs is pretty straightforward and has many benefits over natural mating.

​If you are trying to decide a breed to use on your farm, read more about some of the modern breeds of pigs here.  You may also be interested in heritage breeds of livestock if you are farming on a small scale.

how to choose a boar to breed to your sow or gilt

You can be given two types of information about a boar.

You can be given performance data or expected progeny differences, or EPDs for short.

To learn more about EPDs, check out this article about reading and understanding EPDs.

Performance data is data that was collected from that animal.

EPDs are different. EPDs are used to give a prediction of the animal's offspring's expected performance data.  The EPDs compare that boar to other boars similar to him.  This is commonly seen with purebred boars.

Breed associations release EPD data for purebred animals. For example, if you are looking at EPD data for a Hampshire boar, the EPD will compare that boar to other Hampshire boars, not Landrace boars.

​In this article, we will look at the simpler of the two, performance data.

choosing a boar for your gilt or sow to breed

There are numerous types of performance data that can be considered when choosing a boar.

The data collected is used to measure how productive that animal is.

Days to 250

Pigs are typically considered market size at 250-270 pounds.

One of the most common forms of performance data collected is Days to 250.  Days to 250 is literally the number of days that it took that pig to reach 250 pounds.

Now, if you think about it, the fewer the days it took that animal to reach 250 pounds, the better that animal converts feed into muscle tissue.

Some pigs will reach 250 pounds in as little as 150 days, while some pigs will take 200 days to reach the same size.  The pig that reached 250 in 150 days will consume feed for 50 days, or almost two months less than the pig that took 200 days.  Most people would agree that the fewer days needed to reach 250 pounds, the better.


Another commonly measured performance data would be backfat.

Pigs that are raised commercially today are bred to be leaner all over and have very little fat present.

The amount of backfat on a pig is measured in one of two ways.  The least invasive form of measuring would be with an ultrasound machine.  However, this requires an ultrasound machine, so not all producers can easily measure backfat this way.

Backfat can also be measured by making a small incision on the back and inserting a device to measure the backfat.  Most pigs today will have backfat well under an inch with many pigs falling around half of an inch of backfat.

Backfat amounts will vary of course depending on the individual pig, but with breeds as well.  Some of the fattier pig breeds such as the Berkshire or Tamworth will have thicker amounts of backfat.

Loin Eye Area

LEA, or loin eye is also frequently measured.

Loin eye is a valuable measurement, as it measures the area of the loin in square inches.  The loin is the muscling along the back of the pig that would be cut in to pork chops if the pig was processed.

For loin eye area, you want a large number.  A small number means that you would get small chops from your pigs.  Larger chops are always better. :)

Loin eye area is typically measured via ultrasound.  When an animal is harvested, loin eye area can be measured as well but that doesn't do the producer any good unless semen was collected before harvest if they were planning to use the animal for breeding purposes.

Pigs will vary a good bit in loin eye area. If your main goal is producing animals for harvest, I would aim for a loin eye area as close to 10.00" as possible, and try to stay away from anything below a 7.5" - 8.00".


is a frequently measured piece of performance data.  IMF % stands for % intramuscular fat.

The intramuscular fat percent refers to the marbling quality of the meat. Marbling, or the intramuscular fat, is the white striations of fat that you see when you look at a cut of meat.  This is not the fat around the edge of a cut of meat, but the small flecks of fat within the muscle tissue.

Again, commercial pigs have been bred to be extremely lean, so many pigs will carry a low IMF %.

I personally prefer a higher IMF %, as this meat tends to have better texture, flavor, and is juicier.  There is nothing worse than eating a dry pork chop.  The higher the IMF %, the juicier that pork chop is going to be when it is cooked.


Another common piece of performance data is Stress. 

Pigs are easily stressed, especially due to heat as they cannot sweat and therefore have a hard time cooling themselves. Pigs that have become stressed will have poor meat quality and can even die.

When you are looking at performance data for a boar and see stress, that means that the boar has been tested for the stress gene.  If he is a carrier of the stress gene, he may stress easily and he may pass this undesirable trait to his offspring.

Stay away from boars that have tested positive for the stress gene, especially if you haven't tested your gilts or sows. The stress gene is thought to require two copies to have detrimental effects, so one copy of the gene won't necessarily cause your pigs to stress overly easy.

However, having a herd that doesn't carry the stress gene will make it easier on you when you have to transport your animals either back home, to the vet or to market.


Napole is another piece of data that you will see when looking at boars.

This is another gene that is known to cause poor meat quality. The Napole gene is frequently called the "Acid Meat Gene" as it causes an acidic muscle tissue.

This acidic meat has poor texture and taste.  Similar to the stress gene, stay away from boars that have tested positive for the Napole gene, especially if you aren't sure whether your sows and gilts carry the gene.

The Napole gene is thought to be dominant, so even if a pig only has one copy of the Napole gene, the animal will be prone to have poor meat quality.

All of these pieces of data can be used to estimate what you should see in the boar's offspring. If a boar only takes 160 days to reach 250 pounds, then you could expect his offspring to reach market weight fairly quickly as well.  If you have a sow that you believe is too fatty and you want to produce a leaner pig, you could choose a boar with a lower backfat.  That would give you offspring that are less fatty.

If you want even more information about choosing a boar, check out Iowa State University's Swine Judging Handout.  They look at both performance data and physical traits.

Once you decide what's important to you, then you can start choosing a boar.

Decide first on what is important to you, and then start looking at the numbers.  You won't be disappointed that you did!

If you want to create pigs that have lots of lean meat, then choose pigs with a smaller backfat number.  If you want pigs that produce large amounts of meat, look at loin eye are numbers.

You always want to avoid pigs that are known to carry the Napole or stress genes. These genes will create illness in your pigs.  These are also passed onto offspring, so if the boar has these genes, the piglets can get them also.

Once you've determined what's important to you, start looking at pigs.  These numbers will give you more information about how the boar stacks up compared to others.  However, make sure that you view the boar in person if possible.

A boar could have the best numbers on paper, but could have other illnesses that don't show up in the data.  Data is excellent to have, but make sure the animal is healthy and sound also.

​If you purchase a boar or semen, make sure that you are buying from a reputable breeder.  A good breeder will only sell healthy, sound animals, which is what you want.  Never purchase from a breeder that refuses to show you their animals!

​If you haven't yet, click here to grab your FREE copy of the Livestock Planning Guide and get instant access to my foolproof method for planning for livestock so you can start raising animals for delicious, homegrown meat, eggs and dairy!

Choosing a Boar, Livestock Planning Guide

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What is important to you when you're looking at boars?  What kind of pigs do you raise?  Let me know below!

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Hey, I'm Shelby!

Founder of Garden. Farm. Thrive.

I'm a multigenerational homesteader, former high school and college agriculture teacher, and your guide for embracing a simpler, more traditional lifestyle. Come along as I teach you how to grow your best garden, raise chickens and other livestock, learn traditional skills and create the homesteading haven of your dreams.

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