When chicks hatch, they have a weak ability to regulate their body temperature, so bathing them is not recommended. A chick's downy coat provides warmth and maintains a proper body temperature. Wet water can cause the chick's body temperature to dissipate too quickly, possibly causing colds or other health problems.
However, once the chicks grow up and have full feathers, they can clean and bathe themselves. Under suitable environmental conditions, such as sunny and moderate weather, chicks can dig and roll in dry soil to remove dirt and parasites from their bodies.
In short, it is not recommended to bathe newly hatched chicks to avoid causing health problems. Adult chickens are usually able to clean and bathe themselves, and appropriate environmental conditions can be used to promote their self-cleaning behavior.
