Why are my Cornish Cross Broiler Chickens Dying?

I keep batches of cornish cross broiler chickens throughout the year. One of the challenges I have faced is mortality. While I have not had cases where my entire flock was wiped out, I have had my share of losses. 

Cornish Cross Broiler chickens will die mot many causes. These include overheating, heart attacks, diseases, weak chicks, and health conditions such as water belly. 

Some cornish cross broilers will die when they are as young as one day old and others when they are due for processing. I have heard cases of poultry keepers who lost entire flocks, the night before processing. 

If your cornish cross chickens are dying, chances are high they are dying because of water belly, sudden death syndrome, heat, cold, pilling, physical injuries, and predators Diseases can also lead to the loss of some of all your cornish cross broiler chickens. Knowing what can kill your chickens will help you put in place preventive measures to make sure your broilers reach maturity.

Water Belly (Ascites)

Ascites or water belly is a common condition in broilers such as the Cornish Cross. It is a condition where the lungs and heart of the chicken cannot support the oxygen demands of the fast-growing body.  

This means that the heart and lungs will supply less oxygen to the other organs and muscles that desperately need it to function normally 

Water belly occurs between 6 to 8 weeks and is common in areas of high altitude, where there are lower levels of oxygen. 

Symptoms of water belly

Water belly is characterized by abdominal swelling, where the stomach feels like it has fluid, akin to a balloon. 

The chicken will look like it is struggling to breathe and will make choking sounds. The cornish cross chicken that has ascites will appear lazier than other birds. They will have a low appetite and will grow slower than the other birds due to low feed intake and low oxygen supply in their bodies. 

The wattles and combs of chickens with water bellies will turn blue in severe cases. This is because the much-needed oxygen will be supplied to vital organs, leaving out non-essential organs such as the wattles and combs. 

To confirm if the bird has a water belly, a professional will draw fluid from the stomach. Positive cases of water belly will result in a yellowish fluid, that is secreted from the liver. 

Water belly has high mortality rates. Broiler chickens with a water belly will most likely die.

Causes of water belly in cornish cross broilers.

Water belly is brought about by various reasons. These are:-

  1. High attitude areas.
  2. Rapid growth.
  3. Respiratory diseases.
  4. Poor nutrition.
  5. Poor genetics.

Flip Over Disease

Sudden death syndrome also known as flip over disease is a condition where cornish cross broilers chickens are found dead, lying on their backs. It happens with no warning or symptoms. The broiler chicken stretches its neck, gasps for air, flaps its wings, falls on its back, and dies. 

The highest percentage of chickens affected by the flip-over disease are males. It occurs mostly on fast-growing meat birds. Sudden death syndrome rarely occurs on slow-growing chickens. Due to this reason, it is thought that the cause of flip-over disease is metabolic due to a high intake of carbohydrates. 

Since the cause of flip over disease is not scientifically proven and the disease has no symptoms, it is hard to tell if the chicken died of flip over disease. Experts conclude that the cause of death is certainly flip over disease if the chicken is found lying on its back. The chicken will have no other external or internal symptoms. 

Flipover disease can occur when cornish cross chickens are 3 days old to when they are due for processing but the peak occurrence of sudden death syndrome is between 12 and 28 days of age. If your cornish cross chickens are dying in the second, third, or fourth week, with no prior warning signs, chances are that it is flip over disease. 

Flipover disease has no cure since the cause is not known and has no symptoms or warning signs. Reducing the amount of feed given to cornish cross broilers has been known to reduce the chances of the chickens dying from the flip-over disease. This slows down their growth rate, giving a chance for their organs to grow to sustain their fast-growing muscle structures. 

Slowing down the growth of cornish cross chickens can be achieved by either taking away their feeders at night, reducing the number of light hours, or feeding the chickens with a low carbohydrate diet.


Cornish cross broilers are not efficient in managing heat stress due to their rapid growth and huge muscles. 

Heat stress is a condition where a chicken cannot lower their body temperatures when it is hot. Heat stress can lead to death through heat strokes. The optimal body temperature for chickens is 104 to 107 degrees Fahrenheit (40 degrees Celsius to 41 degrees celsius). Heat stress gets worse in areas of high humidity. 

The signs of heat stress in cornish cross broilers are panting, rapid breathing, loss of electrolytes, outstretched wings, erect feathers, loss of appetite, increased drinking, diarrhea, droopiness, and lethargy. At the final stages that lead to death, the chicken will be staggering, will experience seizures and disorientation. If no action is taken at this point, the chicken will eventually die. 

To prevent and treat heat stress in cornish cross broiler chickens, provide the birds with water throughout. You can use a block of ice in their drinking water, in order to keep their water cool for long. Electrolytes in their water will assist in replenishing the electrolytes that their bodies a losing. Providing shade will create a cooler area where the chickens can shelter themselves. This is important if you are raising pastured broilers. Make sure the coops or chicken tractors are well ventilated to allow for hot air to rise. 


Cornish cross chickens can get affected negatively by cold. The main reason for this is that they feather more slowly than other chicken breeds. Cold is one of the reasons most backyard chicken keepers and homesteaders do not raise meat chickens over winter. 

While cold temperatures might not directly kill chickens, it can lead to them pilling us so as to keep warm. This can lead to trauma and injuries that can lead to immediate death. Cornish cross chickens get injured easily since their muscles and bones are not as strong as other breeds. 

It is advisable to observe the way chickens are behaving when it is cold. If they are pilling up together, then it is time for an intervention. You will need to provide some form of heating like heat lamps or heating mats. 

Trauma (Physical Injuries)

Cornish Cross chickens may experience trauma – external or internal injuries that may lead to sudden death. 

Physical trauma in Cornish Cross broiler chickens may be caused by impact on the surfaces of the coop or tractor, feeders, and waterers. It may be a result of the chickens pilling upon each other. 

Cornish Cross chickens may pile on top of each other when it is too cold, too hot, they feel threatened, or when fighting to get space at the feeder and waterer. 

Injuries in broiler chickens may be also caused by an accident when closing the door or the coop or moving the chicken tractor. 

Signs of physical trauma in broilers are lethargy, lack of movement, and lower activity levels. These injuries might lead to death if not attended to.  Since the bird might not be able to drink and eat properly, it might die of starvation. 

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About James Polystead

I grew up on a small farm. My parents used to grow food and keep animals for our sustenance. They would sell the surplus to make an extra coin to supplement the income from their jobs. I am taking the same path. I have over 40 chickens for eggs and meat. I also grow vegetables in my backyard. follow me on Twitter

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