5-6 weeks old broiler chickens dying indiscriminately:

I'll really feel sorry if you’re experiencing sudden losses in your broilers. At 5-6 weeks of age, broilers are in their rapid growth phase and close to market weight. Deaths at this stage can happen from several possible causes. Here are the most common reasons:

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🔹 Infectious Causes

1. Viral diseases

Newcastle disease – sudden deaths, respiratory distress, nervous signs.

Infectious bursal disease (Gumboro) – immunosuppression, watery diarrhea, high mortality.

Avian influenza (in some regions).

2. Bacterial diseases

Colibacillosis (E. coli septicemia) – often secondary to poor ventilation or wet litter.

Clostridial infections – sudden death with bloated carcasses.

Salmonella / Pasteurella (Fowl cholera) – septicemia and rapid death.

3. Parasitic diseases

Coccidiosis – blood or mucus in droppings, pale comb, dehydration.

🔹 Non-Infectious Causes

1. Management / environment

Heat stress – overcrowding and poor ventilation can kill birds suddenly at this age.

Poor ventilation – ammonia build-up damages lungs and predisposes to infection.

Sudden weather changes – broilers at 6 weeks are very sensitive.

2. Nutrition

Feed contamination (moldy feed, aflatoxins, rancid fat).

Salt toxicity / imbalance of calcium-phosphorus.

Vitamin deficiencies (esp. Vit E/selenium → sudden deaths from encephalomalacia or muscular dystrophy).

3. Heart / metabolic issues

Ascites (water belly) – common in fast-growing broilers, especially if oxygen is low.

Sudden death syndrome (flip-over disease) – broilers die suddenly on their back, usually well-fed and fast-growing.

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🔹 What you can do immediately

• Check environment: ventilation, overcrowding, temperature, litter moisture.

Examine carcasses: look for bloated abdomen (ascites), hemorrhages in intestines (coccidiosis), pale/swollen livers, or any obvious lesions.

• Review feed/water quality: ensure no mold, toxins, or contamination.

Separate sick birds quickly.

• Consult a vet/lab: send dead birds for postmortem exam to confirm cause.

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👉 Since the birds are already 6 weeks (almost market weight), the most likely culprits are:

• Heat stress or poor ventilation → ascites or sudden death syndrome.

• Coccidiosis flare-up.

• Viral disease outbreak (Newcastle, IBD)

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Dr. Haider Farooq

Director Sales & Marketing(Noors Pharmaceutical)