Utah Code § 4-25-102

For the purpose of this chapter: (1) (a) "Estray" means: (i) an unbranded sheep, cow, horse, mule, or ass found running at large; (ii) a branded sheep, cow, horse, mule, or ass found running at large whose owner cannot be found after reasonable search; or (iii) a swine found running at large whose owner cannot be found after reasonable search. (b) "Estray" does not mean any unweaned animal specified in this section that is running with its mother. (2) "Feral swine" means any species, or hybrid species: (a) of the family Suidae, including the European boar, the Eurasian boar, the Russian boar, a feral hog, or a domestic pig; (b) that is not conspicuously identified by an ear tag or other form of visual identification; and (c) that is roaming freely upon public land or private land. (3) "Swine" means any domesticated species of the family Suidae that is conspicuously identified by an ear tag or other form of visible identification.