Rashi on Leviticus 22:27/רש"י על ויקרא כ״ב:כ״ז

1כי יולד WHEN [ANY OX etc.] IS BORN… [FROM THE EIGHTH DAY, AND THENCEFORTH, IT SHALL BE FAVOURABLY ACCEPTED AS A FIRE OFFERING…] — The expression יולד “that is born” excludes the case of an animal delivered through the abdominal wall (i. e. by Caesarian section) (Chullin 38b).