Is it ethical to genetically engineer animals to not feel pain so that it is less torturous when we slaughter them for our food?

In 2006, researchers found six Pakistani children who felt no pain due to an inactivated gene, and who constantly had bruises and cuts. One fell into the habit of putting knives through his hand and walking barefoot on coals, before his untimely death.

Still, scientists already know that humans can intellectually dissociate the sensation of pain from how much it bothers them. Lab experiments with mice have also suggested a way to disconnect that pain sensation without totally leaving animals vulnerable to a world of hurt.

What do you think?