Modern poultry farming systems have progressively created optimal conditions for the healthy and stress-free growth of the animals, the most obvious of which are that the animal does not have to struggle to find food and water, which is provided to it abundantly, safely, controlled and well distributed throughout the rearing area, so that there is no competition between animals to reach the food.
The nature of animal husbandry has eliminated the stress that resulted from the need to defend oneself from predators. Modern farming farms are true protected places where animals do not have to seek shelter from the weather and predators as they would if they were outside.
Aggression between animals of the same species, stems from the competitive spirit, but develops in poultry after about 100/105 days while broilers are bred for 45 or 84 days depending on the growth rate of the farm under consideration.