God considered animals that died naturally to be ceremonially unclean. This was true even if they were ceremonially clean when alive. This was because they did not slaughter them according to ceremonial rules. They did not properly drain their blood and dispose of it (see 12:23–25).
You must not cook a young goat in its mother’s milk: This pagan practice was improper because it showed insensitivity to the natural bond between mothers and their offspring (see 28:56–57).