Cow: A cow and her calf were not to be killed on the same day (Leviticus 22:28; Exodus 23:19; Deuteronomy 22:6,7). The reason for this enactment is not given. A state of great poverty is described in the words of Isaiah 7:21-25, where, instead of possessing great resources, a man shall depend for the subsistence of himself and his family on what a single cow and two sheep could yield.