 From BBC Radio 4, this is Fed, with me, Chris van Tulleken, investigating why we eat what we eat, and at what cost. I'm generally someone who likes to think he knows a lot about food, but whilst I understand what happens once food passes our lips, when it comes to the question of how it arrives there, I'm less sure. I want to unravel the tangled story of people and power behind the world's most popular meat. This is Fed.