Genesis 41:27-31

The seven thin and ugly cows stand for seven years, and the seven thin heads of grain burned by the hot east wind stand for seven years of hunger. This will happen as I told you. God is showing the king what he is about to do. You will have seven years of good crops and plenty to eat in all the land of Egypt. But after those seven years, there will come seven years of hunger, and all the food that grew in the land of Egypt will be forgotten. The time of hunger will eat up the land. People will forget what it was like to have plenty of food, because the hunger that follows will be so great.