When I worked with a big cat sanctuary, I picked up chicken on a weekly basis from the local chicken processing plant (Perdue, if I remember correctly). I instantly became a vegetarian.
In the summer, huge semi trucks would be in the parking lot, full of thousands and thousands of chickens that had died from the heat during transport. We would receive chickens off of the processing line that, while dead, still had large, white, live worms crawling out of them. We got the same chickens off the same lines that were going to grocery stores, and they would smell awful and be smeared in shit and bile and feathers and who-know-what. And the people who worked there (mostly Hispanic immigrants) suffered horrendous injuries on a regular basis (one of our board members was a physician who treated them). And all I ever saw was the end of the line – I’m sure casual cruelty of the beginning of the process would’ve been even worse.
(Cattle and swine have it even worse.)