Tare, or shrink, is weight you take off the gross because it isn't really sellable animal — caked mud, manure, or a documented disease deduction. Most tickets have no tare; it defaults to zero.
Tare directly lowers the net weight, which lowers what a per-cwt lot sells for. Apply it deliberately and document the basis — it moves real money.
Technical section
Data model, API, and internals — visible to developers.