Buy 500 kilograms of live weight and you will sell less than 500. Birds lose weight between the farm and the counter, and a few do not complete the journey at all. Neither fact is unusual, and neither is a sign that something went wrong.
What goes wrong is leaving the gap unrecorded. An untracked shortfall looks like a data entry mistake, or worse, like staff error - and both of those get argued about instead of measured.
Separate shrinkage from mortality
They are recorded together and caused differently. Shrinkage follows transit time, loading density, and how long birds wait before sale - all things you control. Mortality points at the supplier, the season, or the condition of the birds at loading - things you negotiate rather than fix.
Collapsing both into one number tells you that you lost weight. Keeping them apart tells you who to talk to about it.
Record it per load so the pattern can show
A single bad load is noise. The same supplier producing above-average mortality across six loads is a finding, and it is only visible if each load carries its own figures.
Per-load records also make the conversation with a supplier concrete. Dates, weights, and counts are harder to wave away than an impression that the last few loads have been poor.
It also settles disputes at the counter
When the day's weights are recorded as they happen, a customer disputing short weight is answerable from the record instead of from memory. That is worth as much for the relationship as it is for the ledger.
Honest shrinkage records make the rest of the books believable too. If the weight gap is documented, the sales figures around it stop needing to be defended.