'Year old' in the Bible

And he said to him, "Take for me a three-year-old heifer, and a three-year-old female goat, and a three-year-old ram, and a turtledove and a young pigeon."

Abraham fell to the ground, laughed, and told himself, "Can a child be born to a 100-year-old man? Can a 90-year-old Sarah give birth?"

This is the account of Jacob. Joseph, his seventeen-year-old son, was taking care of the flocks with his brothers. Now he was a youngster working with the sons of Bilhah and Zilpah, his father's wives. Joseph brought back a bad report about them to their father.