It "ain't" for me, but......... they breed horses to run fast. That means breeding them will skeletal structures too weak for their body size so that they will be faster. They breed hogs to mature faster for slaughter etc.
Those fighting chickens live better lives than any KFC chicken. You know they live better lives than the hoods where Popeye's raises their chickens. Imagine that place. Drive-by cage shooting every damn day.