Cockfighting.
In the olden days dating back to the twenty-first century, humans, especially farmers, would select their prized chickens from their farms, feed them with specific energy-boosting chicken feed, lead them to increased levels of aggression, and then later force their chickens into fighting others for money or just for entertainment.
In those chicken fights, the two senseless birds would only run on instinct, unaware that their pain, turmoil, and inevitable injuries or even death were simply means of entertainment for the humans betting on them. They didn't care about their well-being, nor did they care about the noise surrounding them. All they cared about was winning.
