'A typical slaughterhouse kills up to 1,100 pigs every hour. The sheer number of animals killed makes it impossible for them to be given humane, painless deaths. Because of improper stunning, many pigs are alive when they reach the scalding tank, which is intended to soften their skin and remove their hair.'

Not most are still alive, they all are. It's tragic if they are improperly stunned but most are knocked out.

As for the chickens, they are hanged upside down yes, than they go trough an electrified pool which instantly knocks them out. It all goes really fast.