There is no requirement for ritual slaughter (shechita). Theoretically, the horn can come from a non-kosher animal, because under most (but not all) interpretations of Jewish law, the shofar is not required to be muttar be-fikha ('permissible in your mouth'); the mitzvah is hearing the shofar, not eating the animal it came from. The shofar falls into the category of tashmishei mitzvah – objects used to perform a mitzvah that do not themselves have inherent holiness. Moreover, because horn is always inedible, it is considered afra be-alma ('mere dust') and not a non-kosher substance.