He killed it; either Moses, as in the following clause, the pronoun being put for the noun; or some other person by Moses's appointment; which may be the reason why he is not named here, as he is to the sprinkling of the blood, which was an action more proper to the priest, and more essential to the sacrifice, as the learned have observed.
Related Commentaries of Leviticus 8:19
Leviticus 8:19
19 And he killed it; and Moses sprinkled the blood upon the altar round about.