Anyway, I've been a vegetarian since not long after seeing that, going on 25 years now. I can understand and sympathise with feeling as you did. I understand but don't sympathise with the way your colleagues left the dirty work to you, very hypocritical of them. I've known a few vegetarians like that, it's more about their personal disgust and hence, comfort, than it is about anyone else's suffering. They're also the most fickle, in my experience, hunger will soon overcome less important emotions, like notions formed as child. They're the ones you'll hear saying “I was vegetarian for years but one day I was famished and all I had available was a burger… never looked back”.
You have principles they are yet to know.
[1] http://www.gutenberg.org/files/153/153-h/153-h.htm#chap10
I would say, no healthy animal wants to die.
This doesn't mean that any pig could articulate "I'm going to die". That isn't necessary. Nearly every ungulate (maybe not moose?) has a built-in mortal fear ready to surface at any time. New events, or repeated events with bad associations, bring out that fear. It takes a great deal of training to relax that.
Related... the silence of the lambs thing I witnessed first hand. A bunch of sheep taken off to be slaughtered, standing in complete silence. Welsh sheep are never silent, so it spooked me a lot. No visual cues as to their impending doom, yet they all stood there like ghosts.