A lamb was sacrificed on passover

The feast of the Passover is a commemoration of the last of the plagues that preceded Israel's exodus from Egypt. Warning that he would slay the firstborn in the houses of the Egyptians, God told the Israelites to slaughter a lamb and place its blood on the doorposts and lintels of their houses. God said that when he saw the blood he would "pass over" the house and spare its inhabitants from the coming plague. When the Egyptians realized that their firstborn had been slain, Pharaoh released the people of Israel from their slavery. The people departed in such haste that they could not allow their bread to rise and so ate unleavened bread. The central element of the Passover celebration in subsequent generations was eating a meal that included lamb and unleavened bread. The Passover took place in the spring and during the festival people made a pilgrimage to Jerusalem. Jesus was crucified at the time of the Passover celebration.

Exod 12 - Passover observances