The "lost son" goes and enjoys his FAT TUESDAY before sacrificing all during his season of LENT, then the "father" is glad he returns to the church and celebrates in the great feast of EASTER.
I hope I showed you how people can make up anything from the Bible. They can even try to make up a vegetarian message out of it.
This parable appears only in the Gospel of Luke. It is made up by the author. It is the third parable in a series, the first about the lost sheep, the second about the lost coin, this one about the lost son. The god of the Jews is a cold killer and the authors are trying to make a kinder, gentler image for him, so this parable shows how forgiving and festive God can be.
It has nothing to do with a message about killing animals. The author (known as "Luke") may say it is kindness to save a cow on the sabbath in the previous chapter, but then I don't know where you read into the story that killing a calf is "maximum pain." If your personal beliefs reject eating animals, I am sure you can find things in the Bible to support your beliefs.