BeefAI™ Stayability/Longevity (Daughter Herd Life) — Methodology and Technical Reference: A Six-Trait Weighted Composite Model for Predicting Daughter Herd Life

BeefAI™ Stayability/Longevity is a deterministic six-trait composite engine that predicts the expected productive herd life (years) of a bull's daughters. Input traits — Mature Body Condition (30%), Claw Set (20%), Foot Angle (15%), Days to Calving (13%), Docility (12%), and Leg Angle (10%) — are converted to goodness scores, weighted by heritability, and mapped to a predicted longevity in the range 3.0–12.0 years around a 7.0-year base. This document describes the full mathematical methodology, biological rationale, trait heritability references, and calibration approach. All scoring is deterministic and reproducible from TACE-published EBV data. Calibrated to the March 2026 TransTasman Angus Cattle Evaluation (TACE), published by Angus Australia. Engines: APEX • ACE • CER • MEI • GENEius • BeefAI Signals™ • CEI • BAI-CERT