I think tripe is the only use an industrial abattoir would have for the stomach and that's likely to be handled by a human. My guess is that they have a bucket

I think tripe is the only use an industrial abattoir would have for the stomach and that's likely to be handled by a human. My guess is that they have a bucket or something that they put foreign material into. Hmmm, but I wasn't thinking of pet food: that would probably be ground.