I would be interested in a program to breed farm animals to be as stupid as possible. If we could give cows the intelligence level of a chicken, for example, I would feel better about eating them.
Truthfully, I don't think the capacity to suffer hinges on intelligence. Most animals are wired with the capacity for suffering because it's almost always necessary for survival on Earth.
Chickens are pretty stupid. They do stupid survival things like pooping in their feeder, but they'll then refuse to eat their food because they can see it's contaminated. They do stupid social things, like killing other chickens because their pecking order instinct causes them to peck at a visible injury, making said injury worse, but they have social interactions all the same. They go into a panic because of stupid triggers like a rag blowing in the wind and ignore actual dangers like a tractor, but they're definitely able to be scared. They don't learn many verbal commands like a dog could, but they recognize the face of their owner and will do behaviors likely to get them fed. Pigs, some cows, and some goats are as intelligent, emotive, and personable as a family dog, but chickens are just not that smart.
However! They're identifiably, understandably stupid, like a tiny human with terrifically poor planning, observing, memorization, predicting, social, and emoting skills. It's not an alien kind of stupidity like that of a fish, insect, plant, or rock (or computer program). I can say with great confidence that chickens are quite low on the emotion/intelligence spectrum, but in saying that I'm quite confident that they're on it.
If your criteria for animal cruelty is achieving a particular level or capability on the sapience/sentience spectrum, you can feel pretty safe eating chicken. If your criteria is that they not posses intelligence or experience emotions at all, you'd better go pescatarian. Or eat mutton: if sheep have any intelligence at all it's completely undetectable to me.
I grew up on a small farm with chickens. They had plenty of space, were free to roam the yard during the day and yes, they could be vicious and cannibalistic if a chicken was injured.
Have you ever seen free range chickens should something like a lizard runs by? They're pretty vicious on their own without the need for any factory conditions.
Aaaaand your point? Humans are all of these things without being subject to such conditions as jails, war, or enslavement. And while US prisons have no shortage of terrible faults, most prisons around the world are far worse both in their living conditions and their treatment of prisoners, so no idea why you're choosing a single out US prisons specifically.
I assure you, they are not anything like you described. And across breeds, they have wildly different cognitive capacities, so a broad-stroke description like this is inherently inaccurate.
I too have raised chickens and grew up with many people with their own small farms raising chickens along with other animals and speak from my own experience, so please realize that you're assurances are purely anecdotal. Please step outside of your bubble world.
