A cow and her calf were not to be killed on the same day (Lev. 22:28; Ex. 23:19; Deut. 22:6, 7). The reason for this enactment is not given. A state of great poverty is described in the words of Isa. 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.
Dicionário Bíblico Ilustrado de Easton (Easton's Bible Dictionary)
Dicionário Bíblico (Easton)