The invention relates to spray applicator devices and methods of use for vaccinating, or administering probiotics to, avian animals. Said automated spray applicator device comprises a housing, at least one rapidly actuatable automatic spray nozzle, a programmable spray module, for controlling the automatic spray nozzle(s), and optionally a source of pressurized air for supplying pressure to the fluid prior to its entry into the spray nozzles; wherein the programmable spray module is in electrical, pneumatic or hydraulic connection with the at least one automatic spray nozzle; wherein the automatic spray nozzle(s) is(are) in fluid communication with a fluid reservoir/tank; and wherein the automatic spray nozzle comprises an electrical, pneumatic or hydraulic actuator and a nozzle tip.