My son thought it hilarious at age 2ish to say that the chickens didn't know - they didn't know they were for dinner, yum yum!

We live near a farm and have a good butcher locally, so I've always been upfront that the animals are killed and we eat them. Predators eat prey. We talk about what sort of animals eat others. He's getting a bit squeamish now, but I remind him that he ate lamb for dinner and thought it yummy, why can the birds not eat lamb? (We were at a museum with taxadermical tableau.)

I would use the words "died" or "killed" in your explaination. It's part of life. Animals eat each other. My son is 4.5 too and knows Daddy goes fishing and we eat fish - because we've been upfront with it he's not that bothered about the fish dying because they're yummy.