8 Common Causes of Pig Infertility and How to Address Them


8 Common Causes of Pig Infertility and How to Address Them


If you raise your pigs for meat, the idea of breeding them, either by keeping a boar or through AI breeding, has likely crossed your mind. After all, it is usually much more economical to have your piglets born on the farm than to buy them elsewhere.


However, it can be frustrating and stressful when your sows or gilts fail to get pregnant the first, second, third, or more time. While one failure to get pregnant might be a fluke, a sow that repeatedly does not come into heat or take up breeding can be a sign of a serious problem.

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So how do you know what the issue is – and whether you should intervene? Here are some of the most common pig infertility problems and how you can address them.


Why Are My Pigs Not Getting Pregnant?

Whether it’s a failure to get pregnant in the first place or miscarriages, stillbirths, or abortions that are affecting your litters, here are some of the most common causes to watch out for.

READ ALSO: 3 Ways to Prevent and Treat Diarrhea in Growing Pigs

1. Viruses

There are a few different viruses that can cause infertility in pigs.

These include:



Porcine circovirus type 2

Swine influenza virus

Porcine parvovirus

Porcine reproductive and respiratory syndrome

There are medications and treatments for some of these viruses but not all. To prevent them, be sure to quarantine any new arrivals to the farm and administer any available vaccinations.


2. Bacterial Infections

Several bacterial infections can cause infertility in pigs, too. Fortunately, most of these can be treated with antibiotics and prevented with good sanitation practices. The most common bacterial agents to affect fertility include:

E. coli

Actinobacillus rossii




In some cases, if you’re doing AI breeding, the semen can be contaminated with bacteria, too. That’s why only working with a reputable breeder and being sure to follow all handling instructions is so important.


3. Parasites

Getting your sows and gilts on a solid deworming schedule is important if you want to ensure healthy litters of piglets. Pigs should be dewormed regularly, regardless of whether you are using natural dewormers or you choose to use a chemical product.

Eperythrozoonosis is the most common parasitic agent to affect fertility but it’s certainly not the only one.


4. Nutritional Deficiencies or Toxicities

Nutrition is another common culprit behind pig infertility.

Females should have a good body score when they’re bred – you don’t want them to be too fat, nor should they be too thin. Feeding needs to be spot-on or a sow might not implant enough or enough viable young embryos.

Pay close attention to the quality of your feed. Deficiencies in vitamins and minerals like zinc, vitamin B12, riboflavin, pantothenic acid, and choline can all cause breeding problems. Selenium toxicity is another potential issue to watch out for, though not as common as deficiencies of any other nutrients.



5. Mycotoxin Contamination

Many farmers don’t think about the role that mold and fungi play in pig infertility, but it’s important to recognize that they can cause a serious problem. Mycotoxins, which are caused by fungi and mold, are often present in straw bedding as well as in grain.

All kinds of animals, including those that are not breeding animals, can be vulnerable to the impacts of mycotoxins. However, pregnant sows are some of the most likely to suffer problems. Mycotoxins can cause stillbirth and abortion because they damage the placenta. Often, mycotoxins cause miscarriage before you even know your sows are pregnant.

Sanitation is one of the best ways to combat this problem. Wash and dry feed bins regularly and make sure they’re totally dry before you reintroduce them to the pig barn. Don’t use straw if it was baked in damp conditions and consider adding binders to your feed, which helps to absorb dangerous mycotoxins.

READ ALSO: Reasons to Raise Pigs on Concrete

6. Poor Management

Often, pigs can’t be bred because the management is poor. For example, if you have too many pigs living in the same barn or if you practice poor handling techniques (such as moving them too close to breeding or moving them poorly).

Another common reason why a sow cannot be bred is that you missed the heat cycle or mistimed it. Poor heat detection is one of the most common causes of perceived pig infertility, especially when you’re breeding sows via AI breeding.

Even if you’re using a boar, you should not introduce a boar until the sow is definitely in standing heat or standing oestrus. Wait until your sow stands rigid and doesn’t move forward when you put weight on her back. Usually, this is on the second day of the cycle.

The service period should also be highly regimented, with a sow served 2 or 3 times 12 hours apart. This will ensure the greatest odds of pregnancy.

If you’re using a board, try to supervise the servicing. I know, it’s not the most enjoyable way to spend your time – but it’s important to make sure the breeding is as planned out as possible. Record all service activities so that you have a good idea of when your sow will become pregnant and start to show signs.


7. Age Issues

If your gilt has not gotten pregnant yet and you’re curious about why that is the case, it could just be that she is too young. Animals that are mated before 5½-6 months old are not likely to take that first breeding since they just aren’t reaching maximum ovulation yet.

Don’t just “wing it,” either, since gilts that are mated when they are too young often never catch up. You will likely struggle with fertility problems with them for the rest of their lives and they’re also more likely to have small or weak litters in the future, too.


8. Seasonal Issues

Finally, know that the weather can also play a big role in whether your pigs get pregnant.

If you’re breeding animals outdoors, this can be problematic especially if the weather is extremely hot and especially if you’re breeding with boars.

Boars, in particular, aren’t very fond of mating when the weather is hot.

While you can’t control the weather, you should make sure your pigs always have access to drinking water. Ensure that the wallows and source of shade are adequately maintained.


What Are the Odds of Pigs Getting Pregnant?

Many people assume that with pigs, like humans, it’s pretty challenging to get pregnant.

However, pigs are much more “fertile” than humans, meaning your success rate will probably be higher, too. With human females, the odds of conceiving each cycle are about 25-30% (as long as you’re under 35).

With pigs, the pregnancy rate is around 69-77%, depending on when in their cycles they are mated.


Those are pretty good odds!

Of course, you’ll have to make sure you’re following all the tips for working with a boar or for AI breeding. That way, you can make sure you optimize your chances of success.


What to Do If You Have Pig Infertility Issues

If your pig isn’t getting pregnant, I recommend going through the list above in an attempt to identify what the issue might be.


More often than not, mistimed heat cycles are to blame. You might be trying to breed a pig that is too young or just not in a good standing heat yet.

If those issues aren’t to blame, next consider your management practices and nutrition. These are common issues, especially among novice pig breeders. Plus, they’re the easiest to address. If you aren’t seeing signs of any diseases, whether they’re viral, bacterial, or parasitic, then management issues are likely to blame.

Keep good records of everything you do on your farm. If you have to assist a sow at farrowing, write it down. If a sow is serviced by a boar and takes or more importantly, doesn’t take, write it down.

Most importantly, don’t get discouraged if your pig is struggling to get pregnant. No matter how long you’ve been in the pig business, it’s a constant education process – you are always going to be learning, so don’t get down on yourself. Keep trying to pinpoint potential issues and address them.

With any luck, you’ll have a litter of piglets running around in about 3 months, 3 weeks, and 3 days!

Contributed by Rebekah Pierce

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