Does It Matter If Chickens Inbreed?

Last summer we bought a bunch of hens and baby chicks from a local couple. Of course, we didn’t know it then, but there were a few roosters along with the young hens we’d purchased.

barnyard mix chicken
a barnyard mix chicken

Now that they are big enough to know that they are roosters and are jumping on the hens, I’ve been wondering if it matters that they are inbreeding with their sisters or possibly their mama. I don’t exactly want a bunch of deformed chicks running around!

No, it doesn’t really matter if chickens inbreed. This is not something to worry about unless you’re at the 7th generation (at the very least) of continuous inbreeding – which is highly unlikely you can attain.

In fact, this experiment inbred chickens for 17 generations straight with no issues:

This inbred line has undergone 17 generations of inbreeding and still appears to be vigorous.

Inbreeding in Japanese Quail Estimated by Pedigree and Microsatellite Analyses

So inbreeding your chickens for such a long time without introducing new eggs or members to the flock is pretty much impossible. Still, let’s take a closer look at this to see what’s going on!

What is Inbreeding as it Refers to Livestock?

Many people wonder whether it’s safe to breed roosters with hens that are related to them. In some species (humans come to mind, of course) this would be incredibly dangerous.

There are quite a few genetic problems that can arise from repeated or one-time inbreeding, especially as the two relatives that are breeding become closer in genetics.

However, in livestock like chickens, the problems are reduced. You are perfectly fine to inbreed your chickens, particularly if you are only doing it in the short term.

In fact, in animal husbandry, this practice is actually widely used and positively regarded. It’s called linebreeding instead of inbreeding, and basically involves breeders diluting as many characteristics as possible by breeding related animals.

The result of linebreeding is usually the best-looking, most breed standard-conforming bird around.

There are distinct advantages and disadvantages to line breeding, which we will cover below.

The Benefits of Linebreeding

Linebreeding is done primarily to preserve the beloved characteristics of favorite breeds. For example, linebreeding is what allows Orpington chickens to be consistently friendly, Australorps to lay prolific amounts of eggs, and Barred Rocks to be exceptional meat producers.

Linebreeding is often done to preserve dispositions, cold and heat tolerance, tolerance for confinement, appearance, foraging ability, flightiness, meat flavor and density, and egg production. In addition, linebreeding has been done to protect heritage breeds.

As this study on Thai chickens suggests, egg production and average chicken weight didn’t vary too much after inbreeding.

Heritage Breeds – and Why They Are Important

Linebreeding is often done to protect endangered or heritage breeds. While there are hundreds of breeds of chickens you can choose from on your homestead, heritage breeds are some of the most prized species around.

These chickens are those recognized by the American Livestock Breed Conservancy. Heritage chickens must be “hatched from a heritage egg sired by an American Poultry Association Standard breed established prior to the mid-20th century, is slow growing, naturally mated and with a long productive outdoor life”.

A heritage breed, therefore, must be a pure breed. There are very specific standards as to what constitutes a heritage breed. Most heritage chickens are dual-purpose breeds since they are not genetically engineered to be specialized in any way.

Some common heritage breeds include Rhode Island Reds, Bantams, Plymouth Rocks, Hollands, White Leghorns, Delawares, and Wyandottes. Heritage breeds tend to be more readily adapted to your environment, meaning they will need less feeding and can forage and scratch for their own food.

However, to raise a heritage breed flock you almost have to allow for some linebreeding or inbreeding. While you can always introduce new chickens of the same breed, linebreeding is the best way to preserve heritage breed flocks.

All in all, line breeding can be beneficial. If you have chickens with certain health characteristics that you want to pass on – such as resistance to mites or disease – linebreeding can be a helpful way to preserve those characteristics for generations.

If you are trying to maintain a backyard flock for profitable egg or meat production – or simply like having a well-rounded, closed flock – then linebreeding can be quite helpful.

The Challenges of Linebreeding

With every breeding benefit comes a challenge in linebreeding your chickens. For instance, when linebreeding to ensure positive desirable characteristics, you may be losing out on other genetics that aren’t carried through.

If you are breeding chickens specifically so that they maintain a certain color, feather pattern, or disposition, you may lose resistance to disease by breeding two chickens who have poor resistance.

For example, avian influenza, or bird flu, can completely wipe out a flock if the genetics of the group have not evolved with the disease.

Particularly when birds are housed closely together and fed multiple rounds of antibiotics – something that is commonly done in factory-farmed chickens or birds that are raised for commercial egg or meat production – they lose their natural resistance to disease and over time, their genetics become so watered down that they cannot withstand an outbreak of disease.

While this is less common in your standard backyard flock, allowing genetics to evolve naturally by not allowing linebreeding or inbreeding can help prevent your flock from being decimated by disease.

It’s recommended that if you are linebreeding, you occasionally introduce new, completely unrelated breeding stock to increase the genetic diversity of the flock.

You don’t need to stick with the same breed, either. In fact, it’s recommended that, for the healthiest flock, you breed your chickens with different breeds of birds. It’s unlikely that you will be breeding two related chickens this way.

Signs of Inbreeding

In most cases, it is going to take half a dozen generations (at least) for you to see any signs of inbreeding in your flock. When it finally does appear, the signs may be subtle. You might notice physical defects when your chickens hatch, such as:

  • a missing eye
  • a bad leg
  • stunted growth
  • a twisted beak

However, hatching defects can be difficult to rule out as a direct symptom of inbreeding, particularly when you are hatching chicken eggs in an incubator. Incubator errors and defects can often cause birth defects and other abnormalities.

You might see a decline in fertility and hatchability of your eggs, too. Otherwise, it can be very difficult to pinpoint clear symptoms of inbreeding in your backyard flock.

Why You Might Want to Avoid Adding New Genetics

After doing a lot of reading though, it seems it’s not really a big deal if your chickens inbreed. Eventually, you might want to introduce new blood into the line, but it’s not gonna hurt if siblings start mating.

A couple of signs that will tell you it’s time to get some non-related chickens in the mix is when hatch rates begin to significantly decline, or birth deformities begin to occur.

Be sure to monitor egg production and fertility as well, as these can be affected after several generations of inbreeding. Be sure to get rid of any chicks with undesirable traits so as not to breed these bad genes into another generation.

If you decide to add new chickens to your flock, you may have some problems. You can bring in disease and sicken your entire flock, have major fighting and cannibalism issues, or cause other stress-related problems.

When you introduce new chickens for the purpose of switching up your genetics in a flock, it’s important that you do so with the utmost consideration for your existing flock of chickens.

Make sure you consider the health of your chickens, asking the previous chicken owner or hatchery about any health issues like coughing, worms, or mites. Look at the poop of your new chickens before you bring them home – and if you can’t do this, you should quarantine your birds once they get to your farm.

Even if the prior owner or hatchery swears up and down that the chickens were healthy, I recommend quarantining them for 30 days anyway.

This will allow any potential health issues to pop up and give you an idea of issues you could be introducing to your flock. You will also make the transition to the new home as easy as possible for your already-stressed chickens.

Once you do allow your new chickens to meet the old ones, it’s important that you give them time to get used to each other. This will help reduce fighting and help the chickens establish a pecking order before they need to be in the same pen.

An easy way to do this is to put some metal hog panels between the ranging areas for both flocks of chickens. The birds will be able to see each other, but they won’t be able to fight.

Keep an eye on your chickens for the first few weeks. There will be some fighting as they get used to each other and determine the new pecking order.

If you see a chicken that has been injured, make sure you apply BlueKote as quickly as possible to treat the wound and prevent other chickens from pecking at it.

It may also be helpful to introduce distractions to the chicken yard at this time, like toys or extra treats, so that the chickens aren’t so hyper-focused on the newcomers.

Finally, avoid overcrowding your chickens. This is a good rule of thumb in general, but if you’re introducing new breeding chickens to the flock, it’s even more recommended.

You don’t want your chickens to feel pressed for space and fight as a result. You should also try to introduce new chickens at night when they are more sleepy, docile, and less likely to put up a fight.

How to Outcross Your Flock

Once you’re ready to introduce some new blood into your flock, don’t think you have to start from scratch. The best option is to bring in a pair of birds from the breeder or hatchery from whom you already purchased your birds.

This is something that can be beneficial when your chickens have bred through linebreeding so often that the hatchability or health of your flock is suffering.

Choose hatching offspring from the new birds, waiting to see which characteristics they exhibit so you know which new birds you want to introduce to your existing breeding pool. This will give you an idea of any undesirable characteristics you might be introducing.

Best Tips for Breeding a Healthy Flock

Rather than focusing on preventing linebreeding or inbreeding, it’s better to instead start with some of the best breeding stock you can find.

While this can be expensive – particularly if you are raising rare chicken breeds or those that are already expensive or difficult to find – having the best of the best as breeders will reduce the likelihood of genetic problems later on.

Keep in mind, too, that if you plan on using your chickens as show birds, you may want to allow some line breeding to happen. This will preserve the necessary genetic characteristics of your flock that are needed to meet the breed standard.

Otherwise, don’t worry too much about inbreeding in your flock. While many hatcheries advertise their eggs as being from unrelated birds – and admittedly, this can breathe some new life and vigor into a flock – it’s not necessary for every breeding period to be between two completely unrelated birds.

In most cases, you can breed a brother to a sister for five or six generations before you start to see any problems. Remember that selective breeding pass along both good and bad qualities within your flock.

And if you really want to sleep well at night knowing inbreeding won’t be a problem, the cheap and easy solution would be to borrow a male to fertilize your hens…

If you’re hoping to breed birds with specific traits, you might want to use a large breeding pen that will allow you to pull out birds who have weaknesses you don’t want to pass on.

But all in all, it’s unlikely to be a major problem. Some breeders actually prefer to continuously inbreed in order to get the most desirable traits possible. So, if your little rooster jumps on Mama hen… don’t worry about it, that’s just the way nature is designed!

Chicken Inbreeding FAQ

What’s the difference between line breeding and inbreeding?

Line breeding is controlled breeding within a flock to preserve the breed traits, while inbreeding is the breeding between two chickens that are closely related.

What’s the difference between line breeding and intensive breeding?

Intensive breeding is the breeding for several generations between closely related chickens, while line breeding is a lighter form of intensive breeding that’s less strict about lineage.

When is inbreeding a bad idea?

If your flock is experiencing fertility issues with hatching or with egg laying, then you should probably avoid inbreeding.

12 thoughts on “Does It Matter If Chickens Inbreed?”

  1. We’ve raised chickens for quite a number of years now and had never really given this much thought. My Wife brought it up the other day, so we looked into the matter and I have to agree with what you said Kendra. (1 Corinthians 15:39) quelled any suspicions that I had on the subject. (GOD’S diversification program stands strong) !
    Some breeders call this “line-breeding”. every breed of chicken, cow or dog that we have today were produced by line-breeding, which is the art of mating closely related animals together to fix in their genetic make-up, certain qualities or characteristics the breeder(s) may be looking for.

    Some degree of inbreeding is involved when any pair of mated chickens have a common ancestor. (Even mankind to a degree. .)
    It’s always good after a few years to introduce some new birds to the flock, other than what one might have on hand, solely to keep the diversification strong. (Healthier birds).

  2. Animals in the wild dont typically HAVE TO inbreed, but they can if there arent any other options. Inbred offspring is better for the species than no offspring at all, but its hardly ideal.

  3. If there are any deformities in the chicks they don’t survive the harrassment of their fellow chicks. Chickens it seems believe in euthanasia, survival of the fittest, etc. Sometimes this cam be avoided by using a red light in the brooder, but if Mama is raising the clutch, no telling what might happen to that little chick who is born with a twisted leg or some other deformity.

    I agree as do others that it is good to bring in a rooster from another source or blood line. What happens with us, we raise one particular breed, Rhode Island Red, but it is hard to find a true breed and through time the traits you don’t want to see begin to come out in the chicks. You may have a lighter colored one etc. So we have a dark RIR roo from a different farm to help keep our flock dark and eggs a little speckled. It all depends on what you’re looking for in egg production and breed hardiness.

    Not something to be overly concerned with unless you are breeding commercially.

    • Hey Mrs. D I have 1 peahen, it was supposed to be a male but wasn’t so I am getting a peacock but am not sure if they are siblings so I ask does inbreeding affect peafowl

      • I am a long time peafowl breeder. Line breeding peafowl is absolutely no different from line breeding chickens. For peafowl, line breeding is typically to continue, or to produce a specific color and/or pattern. The simplest way to do that is to line breed from birds with known histories, and the best way to do that is from peafowl within your own flock. And most breeders don’t keep large flocks due to the sheer size of peafowl, and the fact that peafowl don’t breed until their second year. So, breeding fathers to daughters and mothers to sons is a common practice. Sibling breeding is not often done.
        Most peafowl breeders do bring in ‘new blood’ every 3rd or 4th generation, to both freshen the gene pool and, more likely, to add a new color or pattern into the mix.

  4. Kendra,

    Thanks so much for this post, my husband and I were just talking about this as we are attempting our first hatching out of chicks right now. I’m happy to read you did the research for us! He figured it was ok, we have heard what Rosann said with our goats and it seems iky at first but I think we’ll get used to it after a couple of years.

    Jane in Alaska

  5. With animals it is called line breeding not inbreeding. To introduce a new genetic line it is called out crossing.
    Lots of chicken fanciers have what they call closed flocks, meaning they will not out cross to outside bloodlines. Many breeders do this to work on egg color, confirmation, and other traits they want to control.

      • Inbreeding is mating of closely related organisms. Linebreeding is selecting a male sire and mating him across several generations of females relatives. I believe inbreeding depression and inherited recessive cull traits are the big fear with inbreeding and how gross it is in in humans. Animals often don’t have those concepts and it doesn’t make sense to apply complex human brains onto chicken teeny brains. We all do it, but it isn’t apples to apples. I read some evidence that close linebreeding. The sire to all the female progeny and their female progeny etc. will concentrate all the dominant and recessive traits to the point where you get inbreeding depression like born blindness, crooked beaks, missing organs, etc…the trade-off is a very concentrated set of genetic traits that become standardized from generation to generation. Chickens that lay a lot of eggs, for example. Still, you’d need the right mix of nutrients, calories, and safe nesting spots to maximize that trait (epigenetics)…but the genetic potential is there. Then if you outcross, you get some interesting things happening…the dominant gene pairs get the dominant gene expressed, the dominant – recessive get the dominant expression, and the recessive – recessive hopefully if they’re bad traits are already culled from two inbred lines. Nature is a cruel, evil overlord…but we can make it better through selection. I prefer to look at the flock as a whole and keep culling hard for the best traits. Make a wish list of the stuff you want and its opposite and cull cull cull. Not necessarily kill, caponized the males and don’t hatch the females, they all have a place on the farm. Keep the very best male and let him linebreed with the very best 1% of the hens. Once you have stably gotten the best genes in your birds, then and only then pull in a similar genetics outside line of birds in the same breed. Rinse and repeat and I believe you will get very similar and very standardized but robust birds that produce what you want and only what you want.

  6. Yup and it’s that way across the board. Goats, chickens, rabbits, dogs… it’s only humans that have a real problem with inbreeding. In the wild animals inbreed all the time.

  7. Well said. I have raised chickens all my life and never experienced any birth deformity in my flocks. It seems that chickens are not discerning about their mating habits and we have never bothered them about it.
    In good flock management, we do tend to introduce more breeds or new “sets” to the flock every few years to keep diversity and variety. My grandparents culled and replaced yearly to keep the flock fresh.
    Thanks for the post; it was well written.


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