What Is an Animal Unit (AU) and Animal Unit Month (AUM)?
Plain-language explanation of AU, AUE, and AUM — and how to use them to compare cows, pairs, yearlings, and bulls.
AU is a common language for forage demand
An Animal Unit (AU) standardizes different cattle into one forage-demand currency. The classic reference is a 1,000 lb beef cow. A heavier pair or bull is more than 1.0 Animal Unit Equivalent (AUE).
AUM turns AU into a time budget
One Animal Unit Month (AUM) is the forage needed to support one AU for one month — commonly planned near 780 lb of dry matter. Four months of grazing for 50 AU is 200 AUM of demand.
Why head count alone misleads
“100 head” could be stocker calves or mature pairs. Without AU conversion, stocking conversations talk past each other. Convert first, then compare to usable forage AUM.
- Pairs often plan near 1.2–1.4 AUE
- Yearlings often plan near 0.6–0.8 AUE
- Bulls often plan near 1.3–1.5 AUE
Use the Animal Unit calculator with stocking rate
Build herd AU and AUM demand in the Animal Unit calculator, then stress-test acres, yield, and efficiency in Stocking Rate. That pairing is how you avoid “we’ve always run this many” decisions in a dry year.
Key takeaways
- •AU standardizes cattle forage demand.
- •AUM = AU × months of grazing or feeding.
- •Convert classes before you argue about head count.
Educational planning content only — not veterinary, nutrition, or financial advice.