What is the ruling on slaughtering and eating chicks after they hatch, or when their weight reaches half a kilogram? Is it a condition for their feathers to be fully grown?

Allah has permitted the consumption of chicken at all ages without specifying a particular age. The Prophet, peace and blessings be upon him, was seen eating chicken, and this is by agreement. It is not permissible to forbid anything except with proof from the Quran or Sunnah. Scholars have not stipulated feeling (the presence of feathers/hair) or reaching a certain age for slaughtering an animal. Rather, some of them stipulated feeling in the fetus for the mother's slaughter to suffice for its slaughter. The Sunnah indicates that feeling in the fetus is not a condition, so the slaughter of the fetus is the slaughter of its mother, whether it has feeling or not. The intent of the fetus having feeling is the completion of its creation.