Why are my broiler chickens dying and how do I find the cause?

Broiler deaths can result from chick quality, brooding problems, heat, interrupted water or feed, disease or injury; the total alone cannot identify the cause. Record daily deaths by house and bird age, along with symptoms, feed and water use, temperature and humidity. Check whether deaths cluster near particular drinkers, in hot areas or among the heaviest birds, and compare with your flock’s usual pattern.

Standard broiler performance benchmarks and veterinary extension guidance describe whole-cycle mortality of roughly three to five percent as common in well-run commercial flocks, with higher losses in open housing and hot seasons. This is a comparison, not an acceptable-loss target. First-week deaths suggest checking chick quality, transport, brooding and access to feed and water. A rise around days 14 to 28 with bloody or mucoid droppings raises concern for coccidiosis or other enteric disease. Late deaths among heavy birds warrant investigation of heat load, ascites and leg problems; none of these patterns confirms a diagnosis.

Check water availability at the drinkers immediately, rather than assuming a full tank means birds can drink. Inspect feed delivery, litter moisture and airflow at bird level. FAO and breed-guide heat stress guidance notes that growth and feed intake decline above roughly 30C, or earlier with high humidity, and severe heat can increase deaths. Improve airflow, maintain plentiful clean, cool water, repair leaks and avoid handling birds during the hottest hours. A sudden drop in water use is an important early warning.

For example, an 800-bird Cobb 500 flock in a naturally ventilated deep-litter house at 33C, stocked at 10 birds/m2, has a stated background mortality of 5.5 percent. That warrants investigation rather than acceptance as normal. Heat is a plausible contributor, particularly as birds approach the target of 2.75kg at 42 days, but the same total could reflect early chick losses or a mid-cycle disease problem. Separate those patterns using daily records before deciding what to change.

Seek same-day professional advice for sudden bloody droppings with rising deaths, a sharp unexplained increase in losses, or severe breathing or neurological signs. Restrict visitors and movement of birds and equipment while the cause is investigated, and remove carcasses promptly and safely. Ask a veterinarian or diagnostic laboratory how to submit recently dead birds for examination and testing; do not begin medication simply because one symptom resembles a familiar disease.