The Torah in Parashat Acharei-Mot introduces the mitzva of kisui ha-dam, which requires covering the blood of non-domesticated animals and birds that are slaughtered (17:13). This obligation does not apply to domesticated animals; after slaughtering a sheep or a cow, the animal’s blood does not have to be covered.
On the level of peshuto shel mikra (the plain meaning of the text), this command should be viewed in the context of the previous section, where God forbids Benei Yisrael from slaughtering domesticated animals in the wilderness except as sacrifices. While the precise meaning of this prohibition is subject to debate among the Tanna’im (Chulin 16b-17a), the straightforward reading of the text – as noted by the Ramban (17:2-3) – follows the view that during the years of travel in the wilderness, Benei Yisrael were permitted to slaughter domesticated animals only if they were offering a sacrifice. This means that if somebody wished to eat the meat of a domesticated animal, he would need to consecrate an animal as a shelamim offering, and bring it to the Mishkan where certain portions of the animal would be placed on the altar and others given to the kohen. The owner would then be allowed to eat the rest of the animal’s meat. Once Benei Yisrael entered the Land of Israel, where it was unfeasible to bring a sacrifice every time one wished to eat the meat of a domesticated animal, it became permissible to do so without offering a sacrifice. This rule applied only to domesticated animals for the simple reason that only domesticated animals could be brought as sacrifices. God wanted Benei Yisrael during this period to eat animals that are suitable for sacrifices only as sacrifices. Non-domesticated animals and birds, which are not offered as sacrifices, were allowed to be eaten in an ordinary fashion. (Some birds are eligible as an ola and chatat, but none are eligible as a shelamim, and thus nobody who would bring a bird offering would be able to partake of the bird’s meat.)
Accordingly, God here presents the instructions concerning all forms of meat consumption in the wilderness, establishing two basic guidelines: 1) slaughtering domesticated animals is forbidden outside the framework of sacrifices; 2) slaughtering non-domesticated animals and birds is allowed outside the Mishkan, provided that the blood is then covered by earth.
The explanation of this requirement to cover the blood likely relates to the reason given for why slaughtering domesticated animals was forbidden. God tells Moshe that this command is issued so that Benei Yisrael would sacrifice only in the Mishkan, “and they would no longer offer their sacrifices to the demons after which they stray…” (17:7). As Ibn Ezra explains, it seems that Benei Yisrael had grown accustomed in Egypt to offering sacrifices to the spirits in the desert. Forbidding the slaughtering of sacrifice-eligible animals outside the area of the Mishkan was a safeguard against pagan worship, to which Benei Yisrael were, apparently, drawn. This same concern likely underlies the requirement of kisui ha-dam. As birds and non-domesticated animals were not commonly offered as sacrifices, there was not the same level of concern regarding the slaughtering of these animals as there was regarding the slaughtering of domesticated animals. Nevertheless, God commanded Benei Yisrael to cover the blood to ensure that the blood could not be used in any sort of religious rite. Although slaughtering these animals and birds was allowed, it was still necessary to protect against pagan worship by requiring that the blood would be covered by earth so it could not be used for any sacrificial purpose. God thus sought to lead Benei Yisrael away from idolatry by forbidding the slaughtering of domesticated animals unless they are brought as sacrifices to Him, and by requiring that the blood of other creatures must be covered after slaughtering.