Sour Crop in Chickens: Cause, Treatment and Prevention

If you own backyard chickens, you have probably heard of the sour crop in chickens. This is one of the common problems in poultry farming. While it isn’t a highly infectious disease that affects the entire flock, it is still best to know the sour crop in chickens’ cause, treatment, and prevention.

What is a chicken crop?

Before getting into the details about the sour crop in chickens’ cause, treatment, and prevention, let’s first know what a chicken crop is and how digestion in birds works. Doing so gives you a clearer understanding of this health issue and better knowledge about your flock.

A chicken crop is a unique part of chicken anatomy that serves as food storage in the bird’s digestion process.

What is a chicken crop

Where can you find the chicken crop? Hold your chicken and point to the right of its breast bone. That is where a chicken crop is located.

This body part plays an important role in how your chickens ingest and digest food.

The digestion process in chickens

Like humans, the digestion process in chickens starts when they take in food using their mouth or beak. Since chickens do not have teeth, they use their tongue to move around food and before swallowing it. Enzymes help in breaking down pieces for easier digestion.

From the mouth, food travels into the esophagus which serves as the pathway between the mouth and crop.

It then lands on the crop which acts as the holding area for food as chickens typically digest their food overnight. Imagine it as a pantry that temporarily stores food while your chicken does activities throughout the day.

You know your chicken’s crop is full when it looks like a lump near its breast bone. Bacteria in the crop break down food further into more digestible pieces before moving it into the proventriculus or gizzard.

More enzymes are added as the food goes into the walnut-sized gizzard where tiny stones and grit turn food into a paste. Afterwhich, this paste is passed onto the small and large intestine where nutrients are absorbed.

After all the digesting, it then turns into waste which is released out of your chicken’s body through the cloaca.

To visualize the chicken’s digestive tract, watch this video: 

What is sour crop in chickens?

Sour crop in chickens, as its name suggests, is a health issue that affects the crop. The crop has bacteria for breaking down food to aid in digestion.

When there are too many bacteria in the crop, typically yeast, that is when sour crop in chickens occurs.

Sour crop is a common problem when raising backyard chickens. Don’t fret, though, as it is not contagious and will not affect the entire coop. However,  you still need to address it right away to avoid complications.

What are the signs of sour crop?

Apart from playing an important role in digestion, the crop also tells you about the health condition of your chicken.

The crop is usually full at night because of digestion that happens at that time. An empty crop that occurs frequently would tell you that your chicken has not been eating enough.

In the same way, a crop that is still full in the morning would tell you that your chicken may have digestion problems including sour crop.

Two major signs help you determine sour crop in chickens: the crop condition and a foul odor. On top of these two, there are also other tell-tale signs of sour crop that you should look into.

sour crop chicken

Full and squishy crop

The best way you can check if your chicken has sour crop is to carefully feel its crop in the morning. A normal crop is supposed to look empty as food should have been digested the night before.

If you feel that it is still full and it looks swollen, check if it is hard or soft. A crop that is full yet squishy would mean your chicken has sour crop. Comparably, if it feels full but hard, it might be an impacted crop.

Chicken owners confuse these two sometimes. The comparison in the latter part of this article will help you distinguish one from the other.

Foul odor

Another sign of sour crop is a foul odor being released by your chicken.

Smell their beak and if you can detect a sour odor similar to fermentation, then most likely your chicken has sour crop. This smell is caused by the overabundance of yeast.

Other symptoms

While the two aforementioned signs will tell you directly that there is sour crop in chickens, you may not notice these right away. There are other common symptoms that may point to sour crop.

The following symptoms may show up in chickens who may have suffered from sour crop for some time already:

  • Lack of energy
  • Unusually less physical activity
  • Lethargy
  • Diarrhea
  • Loss of appetite
  • Weight loss

Why did my chicken get sour crop?

how to treat sour crop

The first thing that would probably come to mind when chicken farmers find out sour crop in chickens is: Why did my chicken get sour crop?

In a nutshell, an overgrowth of the bacteria leads to sour crop. Many factors and triggers lead to this abundance of yeast.

By knowing what these are, you can address the problem immediately and prevent it from happening again.

Slow digestion

Not all chickens are the same – some digest slower than others. There are chickens who have a slower pace when it comes to emptying their crop during digestion.

When the crop is not emptied completely frequently due to slow digestion, the remaining food inside the crop gets fermented which leads to this abundance of yeast, thus, sour crop.

Undigested food and items

Another reason why sour crop occurs is when there is food or other items that remain stuck in the crop.

Food such as long and stringy grass or too much bread and pasta might be hard to digest. These will get stuck in the crop and trigger yeast growth.

Similarly, other household items can also cause this problem. Small items such as plastic and rubber that chickens swallow by accident are difficult to digest and might also get stock in the crop.

Internal injury

Chickens sometimes fail to recognize household items and ingest them. In mild cases, the problem would only be how slow their bodies would be able to digest these items.

However, there are cases wherein items that are not supposed to be eaten, such as nails, rubber, and sharp pieces, injure your chicken’s body internally.

This internal injury will disrupt the body processes of your chicken including its digestion which may result in sour crop, among other problems.

chicken sour crop

Moldy and rotten food

A good and balanced diet keeps health problems away. On the other hand, moldy and rotten food will bring in a whole host of problems including sour crop.

The molds in rotten food can affect the pH balance in your chicken’s crop. This change in pH balance can cause yeast to grow and lead to sour crop.


When chickens get sick or suffer from an infection, antibiotics are part of the course of treatment that veterinarians advise.

The thing about antibiotics is that they are formulated to kill bacteria that cause illness or infection. Sometimes, good bacteria get affected in the process.

When antibiotics kill good bacteria, the bacteria balance in your chicken’s body gets messed up. This may lead to the overgrowth of yeast in the crop.

Poor sanitation

Cleanliness is as important as your chicken’s diet. Dirty coops and living quarters can cause worms in chickens.

These worms can affect the digestive tract of chickens and cause sour crop. [How to Clean a Chicken Coop – When, Why and How Often]

How do you treat sour crop in chickens?

Sour crop is one problem you should address immediately for the condition to not worsen. There are different treatments that you can do at home. Always do this with caution so as not to harm your chicken or cause further damage.

However, home remedies are recommended to alleviate symptoms only. The best action is to seek the advice of your veterinarian.

First, put your affected chicken in another area, somewhere preferably quiet and comfortable. This is to avoid stressing out your chicken and the rest of the flock when doing the treatment.

Limit intake by not giving your chicken food and water for 24 hours so that the crop will be emptied naturally.

Put apple cider vinegar in a syringe and give the liquid to your chicken through the side of the beak. After 12 hours, you can give lukewarm water and a small amount of soft solid food.

Keep an eye on your chicken to see if the sour crop returns. Should your chicken feel better, you can gradually increase its food and water intake until it gets back to normal.

If sour crop continues to occur, inform your vet right away so that medication can be prescribed.

How do you prevent sour crop?

Prevention is definitely better than cure and it saves you the hassle and stress of dealing with sour crop. To avoid sour crop in chickens, you must ensure that they get the best diet and living conditions.

Always prepare fresh water for your chickens to drink and clean food to consume. Check your chicken feed regularly to ensure that there are no molds. Also ensure that the natural food and table scraps you offer to your chickens as treats are safe to eat and easy to digest.

Grit helps in the digestion process so make sure your chickens have a good supply of this.

Since chickens enjoy scavenging, check your area regularly. Clear it from debris, plastic, rubber, and other items that your chicken might accidentally eat.

It is also important to keep your space clean. Good sanitation goes a long way!

Sour croup and impacted crop: a comparison

Impacted crop is another problem involving your chicken’s crop. Because it affects the same body part, people mistaken sour crop for impacted crop.

Below is a quick comparison to guide you on how to distinguish one from the other.

  Sour crop Impacted crop
Cause Overgrowth of yeast in the crop Food debris and items stuck in the crop
Crop condition Full and squishy, content feels like liquid Full and elongated, content is solid
Treatment Emptying the crop if the case is mild, give medication as advised by the veterinarian Lubricating the crop to dislodge the stuck food/debris

Watch this tutorial on how to clear the blockage of an impacted crop:


Sour crop in chickens is a problem caused by the abundance of bacteria in a chicken’s crop. It can easily be prevented and treated. As a chicken owner, know the sour crop in chickens’ cause, treatment, and prevention to know what to do when the problem arises in the future.

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