Killing the Fatted Calf
Two occasions called for the slaying of this animal.
First, if a special guest was to be received and thus honored, the calf was then killed. When the witch of Endor entertained King Saul with a meal, the account says that she "had a fat calf in the house; and she hasted, and killed it" (I Samuel 28:24). The well-known New Testament example was when the prodigal's father said to his servants, "Bring hither the fatted calf, and kill it; and let us eat, and be merry" (Luke 15:23). It was the custom to kill the animal, cook it, and then eat it, in quick succession. Abraham, Gideon, Manoah, the witch of Endor, as well as the prodigal's father, are examples of this. The Bedouin Arabs do this today when unexpected guests arrive. These Orientals would appear to be expert in the art.36
Second, the "fatted calf' was sometimes slain as a special sacrifice or offering unto the LORD. The prophet Amos mentions "the peace-offerings of your fat beasts" (Amos 5:22, Keil). [Manners And Customs of Bible Lands]