Wis. Admin. Code ATCP § ATCP 51.04
In this chapter, and in every local approval or application for local approval under this chapter, the number of animal units kept or authorized at a livestock facility means the maximum number of animal units that are or may be kept on at least 90 days in any 12-month period.
Wis. Admin. Code Department of Agriculture, Trade and Consumer Protection ATCP 51.04
This section accounts for normal day-to-day and seasonal variations in livestock numbers, as livestock are born, received, moved and marketed. See s. 93.90(3) (f), Stats.
Under this chapter, an applicant for local approval must specify the number of "animal units" for which the applicant seeks authorization. If the application is approved, the approval authorizes that number of "animal units." The authorized number is the maximum number of "animal units" that may be kept on 90 or more days in any 12-month period. A livestock operator may not exceed that authorized number without further local approval.
"Animal unit" equivalents, for different species and types of livestock, are shown in Appendix A, worksheet 1 (animal units). The "animal unit" equivalents are based on s. NR 243.03(3) as it existed on April 27, 2004 (the date on which the livestock facility siting law, 2003 Wis. Act 235, was published). See s. 93.90(1m) (a), Stats., and s. ATCP 51.01(4).