This article analyzes a priori contradictory attitudes and discourses related to the killing of a sheep, a cow, and a wolf among Mongolian nomadic herders. Contrary to the killing of a hunted animal, the killing of a domestic animal is always sad and sober. For the herders, according to their understanding of Buddhist ideology, the killing of a domestic animal is associated with the ideas of pollution (buzar) and sin (nügel). In a contrasted way, the killing of a hunted animal, and more particularly a wolf, is joyful. A good hunter is perceived as a “virtuous” and “meritorious” person with high vital potential (hijmor’). In relation to the Mongolian notion of “fortune” (hišig), I analyze the coexistence of different types of morality linked to the killing of a sheep, a cow, and a wolf.