BeefAI™ — Reproduction, Fertility and the Self-Replacing Herd: The Genetic Economics of Angus Cow–Calf Production

Reproduction is the single largest driver of profitability in a self-replacing Angus herd, yet fertility traits remain among the least understood at the point of bull selection. This paper establishes the genetic and physiological basis for the key fertility EBVs available in the TACE/BREEDPLAN system — Days to Calving, Scrotal Circumference, and Gestation Length — and quantifies their downstream economic consequences across the cow–calf production cycle. It demonstrates how sire selection decisions made at a single bull purchase propagate through the herd over multiple seasons, compounding or eroding reproductive efficiency depending on the genetic trajectory established. The paper documents the postpartum interval as the primary biological bottleneck linking calving performance to rebreeding success, quantifies the conception rate and weaning rate consequences of extended PPIs, and establishes the economic cost per empty cow in Australian Angus production systems. It further describes how the BeefAI™ scoring engine contextualises fertility EBVs within a producer's stated herd structure and joining program rather than applying universal thresholds.