..."We're already murdering them, no point in making sure they don't suffer"?
I don't understand, that's not how that works.
"We've already set ourselves up to make them suffer from birth to violent death, no point in changing directions at the end of it." Would be closer. Really, I just have a great deal of trouble buying at face value that people that don't give much of a shit about the animals for every point
before they're offed suddenly claim a conscience at the end of it.
Though it's more not much point in going out of your way to do so. Shouldn't go out of your way to make it worse, either. Mostly it's just a matter of calling bullshit on the suddenly changing amount of concern. Perfectly fine with breeding them to be food, perfectly fine with all the shit that happens before that's varying degrees of bad for the entity (if not always outright overtly harmful, of course), perfectly fine with killing them en masse, but gods forbid they wiggle a little before the butchers start cutting. You're better off pointing to some other reason besides concern to reduce suffering*, because that's a helluva' lot more convincing :V
'Course, if you're one of the folks that actually do care about everything beforehand, more power to you, and a genuinely sincere wish of good luck. You're going to need it, and a double ration keeping the things existent afterwards if you actually pull it off.
*And there's totally other reasons for making them not suffer at various points of the process! It's better for the quality and cost, iirc, and if excess harm is causing psych problems for the folks processin' them, that's a definite issue.