How can we have respect for animals, if not all of them are able to feel emotions?

I explain more clearly: I heard that the hypothalamus or amygdala is what allows animals to have feelings. The problem is that only vertebrates (mammals, and some birds) have that organ in the brain. It’s really all a question of evolution. There are some animals that have them, some that don’t. But here’s the thing: until now, I thought that all animals were capable of emotions, but if the animals that can’t rely only on instincts, that is, programs encoded in the DNA, then on what is based the respect for life?