AUM Calculations

Producer Question from 2013

Q:  I hear people talk about using AUM calculations in their management of range and pasture. What is an AUM? How is it used in pasture and range management? (June 18, 2013)

A:  An AUM is an Animal Unit Month. An animal unit month is a method used to give an estimate of how much forage is being eaten by a defined animal in a month. In range and pasture management related to beef production, an AUM is often defined as the approximate amount of forage that a 1,000 cow with a calf that is less than three months of age will eat in a month. This number based on research is estimated at 26 pounds of air-dried forage per day or 780 pounds per month. Air-dried forage is assumed to be 10% moisture and 90% dry matter.

On range and pasture land, forage production that is available to be consumed by a grazing animal is often given in terms of AUM per acre. In continuous season long grazing usually only 25% of total forage production is estimated to be available for grazing. For example, Sandhills rangeland can vary widely in the amount of forage available that can sustainably be consumed. If a range site is rated in fair to good condition and at this condition is assessed as having 0.4 AUM of forage that can be grazed per acre that means on the average for this range site it would take 2.5 acres per month to feed a 1,000 pound cow.

Dr. Karla Jenkins, UNL Extension Cow-Calf and Range Management Specialist recently recorded a webinar that highlights understanding what an AUM is and its use in range management. On this webinar page, there are also several UNL Extension NebGuides and Publications available that can help explain how an AUM is used in making management decisions on rangeland.

Aaron Berger, Extension Educator
Panhandle Research & Extension Center
University of Nebraska