There's little more cruel than how we treat chickens. About seventy five billion (!!) of them are slaughtered every year, almost every single one of them living short, miserable lives. They are bred to burst out of their biological confines, suffering from torn ligaments and broken bones as a result. Not that the lack of mobility matters much, since they are confined to a cage that's too small for them to turn around, let alone walk or fly. This is most obvious in the massive factory farms in the West and China, but you see pretty much the same thing in the stacks of chicken in cages lining the road across India.
To spend an entire lifetime
In pain because you were bred to put more meat on your bones than they can withstand
Confined to a 1 foot by 1 foot cage where you can sit or (barely) stand but not turn
Brought out of confinement only to have your throat slit
Is an accumulation of cruelty that no combination of nutrition or culture or tradition can justify.
And the cruelest cut might lie in the future: with beef and some other meats being questioned for their carbon emissions, we might be engineering chicken to be even more efficient converters of fuel into protein. Which might be good for decarbonization, but will most certainly be worse for the chickens.
I find it appalling that some so called environmentalists actually think this is a good thing. “For what shall it profit a man, if he shall gain the whole world, and lose his own soul?”