Every Dead Bird Costs Money
Mortality is the most visible and immediate measure of flock health. Every bird that dies represents lost investment in feed, labor, utilities, and throughput. For a 20,000-bird flock with a 5% mortality rate, that is 1,000 dead birds — each one representing approximately $1.50–$3.00 in feed and production costs alone, not counting the lost revenue from that bird's potential sale.
Reducing mortality from 5% to 3% on a farm processing 200,000 birds per year saves $6,000–$12,000 in direct losses annually, before accounting for the compounding effect of improved FCR and processing weights in healthier flocks. Mortality reduction is not just a welfare goal — it is a direct profit improvement strategy.
Understanding Normal vs. Abnormal Mortality Patterns
Total mortality of 3–5% (including culls) is considered normal in commercial broiler production. First-week mortality should be under 1.5%, with most losses in the first 3–5 days. After the first week, daily mortality should be low and steady — 0.05–0.10% per day. In the final week before processing, a slight increase is normal as heavier birds experience more cardiovascular stress.
Abnormal patterns include mortality spikes of 0.3% or more in a single day, which require immediate investigation — the cause could be disease, ventilation failure, heat stress, or a water or feed outage. Mortality concentrated in one area of the house suggests a localized environmental or drinker problem. Mortality increasing progressively over several days suggests a disease outbreak. Mortality primarily at one time of day suggests an environmental problem like heat stress in the afternoon or cold stress at night.
Common Causes of Mortality by Flock Stage
First Week Mortality
First-week losses are primarily due to starve-outs (chicks that did not find feed or water), dehydration, poor chick quality from the hatchery, chilling from inadequate brooding temperature, and smothering or piling. Preventing first-week mortality starts with good pre-placement preparation, correct brooding temperature, and ensuring feed and water are immediately accessible. Post-mortem examination of first-week mortality can distinguish between management-related and hatchery-related causes.
Grow-Out Mortality (Weeks 2–5)
During the grow-out period, mortality is typically caused by metabolic disorders like sudden death syndrome (flip-over) and ascites, especially in fast-growing males; enteric diseases including coccidiosis and necrotic enteritis; respiratory diseases triggered by poor air quality or vaccination reactions; and leg problems and lameness. Sudden death syndrome typically affects fast-growing males between 2–5 weeks and appears as well-fleshed birds found on their backs.
Pre-Processing Mortality (Weeks 6–7)
In the final weeks, mortality risk increases as birds reach heavy weights. Heat stress is the biggest risk during warm weather because heavy birds produce more metabolic heat and have difficulty dissipating it. Cardiovascular failure, including heart attacks during catching and transport, also increases with bird weight. Heavy birds are also more prone to leg problems that can lead to culling.
Mortality Tracking as a Diagnostic Tool
Daily mortality tracking by house, cause, and time of day is one of the most valuable diagnostic tools a grower has. When patterns emerge — higher mortality in one house, a gradual upward trend, or a sudden spike — they point to specific problems. Mortality data becomes even more useful when connected to other records: water consumption, feed intake, house temperature, ventilation settings, and weather data. A mortality spike combined with a water consumption drop and high house temperature strongly suggests heat stress.
Logging mortality observations during walkthroughs, rather than from memory at the end of the day, captures more detail and improves accuracy. A system that records mortality by time of day — with separate entries for morning and afternoon pickups — provides better diagnostic information than a single daily total.