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What Is A Gizzard In A Bird? Know Its Function And Disease!

You might wonder how your pet bird digests hard seeds and crops without teeth! Does the proventriculus grind all the parts or the gizzard?

But what is a gizzard in a bird and how does it work? A ventriculus or gizzard is called the second stomach, gastric mill, or teeth of a bird. It is situated in the hind part and receives enzymes mixed with softened food. By continuously contracting and relaxing, the gizzard grinds the foods properly.

That’s not the end. Gizzard does other functions as well. A gizzard is not free from diseases. Diseases related to gizzard can cause metabolic changes and ultimately lead to death. You can get an idea about the symptoms and treatment.


What Is A Gizzard in A Bird?

The gizzard is a part of the digestive system in a bird. It is also called ventriculus or mechanical stomach. It has two lobes and they are not equal in size and shape. With the two lobes, it shapes round and its surfaces are covered by tendinous tissue.

This covering is thicker in the center and thinner in the periphery. Gizzard has two layers. The outer layer is made up of red tissue and the inner layer is made up of keratinized tissues and has a lot of raised ridges.

However, gizzards should not be compared with the human stomach. Also, the working process of the gizzard is different from the human stomach. The human stomach digests small parts of food.

Foods are broken down into small pieces in the mouth and then go to the stomach. But the bird has no teeth. So, the breakdown process takes place in the gizzard.

Then the gizzard easily grinds the soft foods as teeth do. The inner layer of the gizzard mainly works as teeth and the outer layer helps in movement or mixing the foods by compression.

Bird’s gizzard is full of nutrients. It contains less fat and protein. Poultry gizzards are taken as food rich in iron, vitamin B12, and potassium. People keep poultry gizzards in their diet for their nutritious value.

Function of Gizzard

Gizzard performs some particular jobs like-

  • The main function of a gizzard is the grinding and churning of foods
  • It increases the surface area of food so that the different enzymes present in the digestive system can act efficiently
  • It contains grit or stone, which helps pulverize excess food
  • Gizzard works as teeth
  • It has coilin in the inner surface. This can withstand the potentially damaging effect of hydrochloric acid and pepsin mixed with the foods that are released by the proventriculus
  • The glands present in the gizzard produce more coilin that passes to the surface, where it hardens to replace the worn tissue
  • It helps in mixing endogenous enzymes with foods
  • Not only mechanical digestion but also chemical digestion takes place here
  • It maintains the flow by contraction and food passes to the next segment for absorption

All of the functions are done at a time inside the muscular structure. For all the functions, the gizzard is called a second stomach.

Do All Birds Have a Gizzard?

All the birds have a gizzard. But it varies in size, shape, and thickness. Gizzard mainly breaks down hard foods. Birds have different preferences from each other.

Some birds like to eat soft foods like earthworms, fruits, and insects. These foods are easy to digest. So, they do not go to the gizzard. Rather the digestion process mainly occurs in the proventriculus. This type of gizzard is smaller in size and has thinner walls as they work less.

On the other hand, some birds are likely to take grains. Even pet owners can give them crops or millet-like foods most of the time. In that case, the gizzard does most of the grinding and digestion. So, this type of gizzard is larger, more muscular, thicker, and stronger.

Gizzard-Related Problems In A Bird

Every part of the bird is vulnerable to diseases and infections. The gizzard is less prone to disease. If it gets infected, it is hard to cure. Hence, two conditions are commonly seen in bird gizzards.

  1. Blocked Gizzard

A blocked gizzard is a serious issue occurring in the presence of any indigestible material in the gizzard. That means if the bird consumes plastic products, metal or wire, it will not digest. These materials are stuck in the gizzard and most of the time remain in the gizzard.

Symptoms of a bird having an indigestible object in the gizzard

You can not detect the disease easily. But you may notice some behavioral changes in the bird.

  • Loss of interest in food
  • Became fluffy
  • Vomiting
  • Increase intake of water
  • Less cheerful
  • Pain around the gizzard region
  • Decrease movement
  • white or clear droppings
  • Death

These are the changes you may find.


Immediately go to an expert vet. Flushing out the foreign body is important. For that, they may inject fluid into the gizzard. Antibiotics are given in case of infection. Besides, symptomatic treatment is given.

  1. Erosion And Ulceration Of The Gizzard

Erosion or ulceration can be caused for many reasons. A healthy and proper diet can change this problem completely. Causes of erosion and ulcerations are-

  • Insufficient food intake
  • Presence of toxic substances in food
  • Bacterial, viral, or attack of yeast
  • Starvation

These are the possible causes of erosion. A large dose of a chemical substance can create ulcers within a short time. So, the chemicals should be kept away from the birds.


It shows fewer symptoms.

  • Bleeding
  • Green or blackish discoloration of the gizzard
  • Sign of infection
  • Lesion
  • Loss of appetite
  • Dilated gizzard
  • The Walls of the gizzard get thick
  • Death

Mostly the birds die before any symptoms occur. It is commonly seen in young birds.


  • Give sufficient nutritious foods timely. 
  • Avoid dirty and moldy environments. 
  • Antibiotics are needed as most of the erosion is generalized with infection. You must consult with a vet.

Gizzard-related problems are rare cases. But these two problems cause death easily within a short time. So, you should keep them away from hazardous chemicals and inedible elements.


What a gizzard in a bird and quarries related to gizzards are now clear to you. It is not similar to the human stomach. Rather, the main function is to grind and break down the foods into pieces for better absorption. However, not all bird gizzard has similar working capacity.

The gizzard works less in birds which mainly take soft foods. And the gizzards work more in birds which take mainly crops or grains along with grits or stones. Gizzard diseases are threatening birds’ lives. So, be careful with your little bird’s food and away from chemicals and plastics.

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