Ethical. If I wouldn’t want people torturing dogs, I have no justification to be okay with people torturing cows, pigs, and chickens
Dogs are genetically selected for living together with humans. As such, and unlike their wolf predecessors, dogs are friendly towards us. In many cases, care is reciprocal, in that we more often care about people who care about us. I propose that chickens don’t have even the slightest sense of morality, and don’t care whether their siblings live or die. With this in mind, I think it’s a somewhat justified to torture birds and low mammals, since they don’t care about our or their families’ well-being to begin with.
However, I would never torture a chicken unless I was at least 99% sure it had valuable information, and the future of the farm was at stake.
In this situation, I would say that whatever you currently believe is the minimum, is the actual minimum. If you manage to convince yourself that a higher minimum is required, you have simply updated the variable.