Deuteronomy 12:16

Ye shall pour it upon the earth. — This act was a necessary part of every slaughter of an animal for food. The blood, which is the life, must be poured upon the earth for God, whether the victim was consigned to the altar or not. It was a continual reminder of the necessity for the sacrifice of the death of Christ, to be continued until He should come. Thus the act was, in a sense, sacramental.