AEU/CAO Calculator

Pennsylvania’s Nutrient Management Act states that Concentrated Animal Operations (CAOs) must develop and maintain a nutrient management plan, written by a certified, trained specialist. A CAO is defined as an agricultural operation where the animal density of all livestock on the farm exceeds 2 animal equivalent units (AEUs) per acre on an annualized basis.

Horses are included in this requirement, but any operation with fewer than 8 AEUs is not considered a CAO regardless of the animal type or density.

An AEU is 1000 pounds of live animal weight. If animals are not present on a farm for a whole year, the animal units are adjusted for the portion of year that animals are present.

AEUs for each animal type= [average # of animals on a typical day X animal weight (lb) / 1000] X [# of days animals are on farm per year / 365].

The following calculations are to be used as a guide only. They are based on standard animal weights. If a farmer has records of actual weights of animals on the farm, these may be used, but supporting documentation needs to be complete. Please contact your local Conservation District or a private sector planner for affirmation of your CAO calculation or for additional details.

CAO Calculation: To determine if an operation is a CAO, take the total AEU’s per farm and divide by the acres suitable for the application of manure. Include all acreage (owned AND rented) that is suitable for the application of manure, and is under the management control of the operator.

Animal =
Number of Animals =
Number of Days Manure is Produced =
Number of Acres =


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