Because of that the plains cow is one of the best for a fast culture 20k game. Bonus food in your start city is mostly irrelevant and only matters for how many low food spaces you can work. At any rate its all about shields and plains cow is superior to grassland for a couple reasons, one it starts at 2f2s, which is huge early game for temple, library etc. Two you can work it to 3f2s in 4 turns versus 6, *or*, 2f3s once out of despotism in 6 turns, compared to the second best of wine on hills which takes 12 turns.