Futurology

Panicked animals produce lactic acid which spoils the meat. Even if you don't care about their welfare killing them cruelly is a bad idea.

Sidenote: Temple Grandin, a widely recognized livestock expert, compiled her research papers in a book I flipped through. What was interesting was that only a couple had to do with what she's famous for - designing animal handling equipment. Most of them are actually about the psychology of people working in the meat industry, with one specifically saying you shouldn't hire people who will be violent with the animals.