High mortality because young chickens are not cared for separately, but they are cared only by the mother hen.
20-50% mortality of chicks under 2 months age, due to natural enemies and threats during their free grazing time in the flocks while the mother hen could not fully protect from these hazards.
Cause of diseases and casualties by contacting with other chickens, eating contaminated feed & water during the free grazing time, if the chickens are not put and raised in fencing ground.
Chicken casualties by infectious disease outbreak, due to absence of vaccination practices.