Kaji field guide
Poultry mortality and livability: calculate flock survival correctly
Mortality and livability are simple percentages, but they depend on an accurate bird ledger. If additions, sales, culls or other reductions are mixed together, a clean-looking percentage can still describe the flock incorrectly.
Working formula
Mortality % = deaths ÷ relevant starting population × 100
Livability is commonly expressed as 100% minus mortality when deaths are the only population loss. Other reductions should be tracked separately.
Keep deaths separate from other reductions
Birds can leave a flock for several reasons: death, culling, sale, transfer or correction. Treating every reduction as mortality overstates health loss and weakens later analysis.
Use typed reduction records so the live count can change without losing the reason for the change.
Choose the population basis consistently
For a closed flock with no additions, deaths divided by birds placed is a common cumulative mortality measure. If birds are added or transferred during the cycle, the denominator needs more careful treatment. The farm should document the method and avoid switching methods between comparison periods.
Look at timing, not only the final percentage
A final mortality percentage can hide a short, severe spike. Record reductions on the day they happen so daily and weekly patterns remain visible. A sudden change may point to disease, heat stress, feed or water interruption, management error or another event that deserves investigation.
The record identifies the pattern; diagnosis still requires appropriate farm or veterinary assessment.
Connect mortality to performance and money
Mortality changes the number of birds available to carry feed and other costs or generate revenue. Review it alongside feed use, growth, treatments and financial performance to understand the full effect on the flock.
Practical checklist
- Record deaths on the day they occur.
- Use separate reasons for death, cull, sale and transfer.
- Confirm the live-bird ledger after every reduction.
- Review daily patterns as well as cumulative mortality.
- Compare similar bird types and ages.
- Investigate spikes rather than relying on the percentage alone.
Use the same records in Kaji
Flock management
Kaji keeps these calculations connected to the flock, inventory, health and money records that support them instead of asking you to maintain a separate analysis notebook.