It’s been over two years since David Olmos Herrera worked at the JBS Swift & Co slaughterhouse in Louisville, Kentucky, but he can still remember the perpetual filth, the heat from the massive by-product cooker and the smell of dead animals. At the Butchertown area plant, around 10,000 pigs are slaughtered and processed every day. And the killing never stops, according to Olmos Herrera, even when equipment breaks down. As a result, he says, the overflowing animal parts and fluids — and the overpowering smell — created near-impossible working conditions…