No victim was to be offered in sacrifice until it was a week old. The meaning of this law appears to be that the animal should realise a distinct existence in becoming less dependent on its mother, and able to provide for its own wants.
Related Commentaries of Leviticus 22:27
Leviticus 22:27
27 When a bullock, or a sheep, or a goat, is brought forth, then it shall be seven days under the dam; and from the eighth day and thenceforth it shall be accepted for an offering made by fire unto the LORD.