Sentience as in "the capacity to experience feelings and sensations":
https://en.wikipedia.org/wiki/Sentience. I don't want to be too philosophical, just consider that both chickens and cats will complain if you poke them with a stick. I'm allowing for something like cricket powder.
I think we agree about pets. Many people treat pets like people but when it comes down to it, they're not, and people won't treat them that way when it counts. Most people won't starve their family to pay for medical care for a pet. The pretense bothers me and feels hypocritical to an animal that trusts its owner so much.
I'm vegetarian in a one-animal-at-a-time sense. I sometimes think of it in terms of killing squirrels, since I see a lot of squirrels every day. For every burger you eat, imagine you have to go out and stomp a squirrel to death. I don't particularly care about squirrels but doing that would be pretty gross and traumatic, so if it's all the same I'll just eat some beans. The benefit to the environment is similarly incremental.