Genesis 41:19
And, behold, seven other kine came up after them, poor and very ill favoured and leanfleshed, such as I never saw in all the land of Egypt for badness: And, behold, seven other kine came up after them, poor and very ill favoured and leanfleshed, such as I never saw in all the land of Egypt for badness:
Pharaoh himself is recounting his first dream to Joseph. In that telling he stood on the bank of the river when seven fat-fleshed and well-favored cows came up out of the river and fed in a meadow, and after them the seven other cows came up. That second group of seven is poor and very ill-favored and lean-fleshed, worse in badness than any ever seen in all the land of Egypt.
The seven thin, ill-favored cows stand for seven years of famine in Egypt. Those famine years follow seven years of great plenty. Their exceptionally poor and terrible appearance shows beforehand how severe the coming scarcity will be.