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].