Charles Ellicott Commentary Exodus 22:30

"Likewise shalt thou do with thine oxen, [and] with thy sheep: seven days it shall be with its dam; on the eighth day thou shalt give it me." — Exodus 22:30 (ASV)

Your oxen. —Rather, your cattle. The word used is applied to horned cattle of either sex.

Seven days it shall be with his dam. —Compare Leviticus 22:27. The main object of forbidding sacrifice before the eighth day would appear to have been regard for the health and comfort of the mother, which needed the relief obtained by suckling its offspring. There may also have underlain the prohibition some reference to birth as an impure process. Compare the circumcision of the male child on the eighth day.