The invention relates to the use of a cyclone separator for separating keratin particles originating from poultry out of a gas, in particular air. The separated particles comprise down particles. The invention furthermore relates to a climate chamber for hatching eggs and/or keeping poultry. Said climate chamber comprises a substantially closed compartment having two opposite side walls provided with one or more passages; as well as a substantially closed duct which extends outside the compartment and connects one of said side walls to the other of said side walls so as to form a substantially closed circuit together with the compartment. Said climate chamber furthermore comprises a cyclone separator, the inlet of which ends in the substantially closed duct and the outlet of which ends outside the closed duct for discharging into the environment.