Abstract: Methods are provided for improved immunization against coccidiosis and other bacterial, viral, or parasitic diseases in poultry. One method includes administering a solution of Propionibacterium acnes suspended in normal saline to a chick at age day one, following hatching. An anticoccidial vaccine and/or other vaccine is then administered to the chick such as by oral administration. Alternatively the method includes the steps of aseptically injecting Propionibacterium acnes in ovo at about day 18 in development, followed by post-hatching vaccination with an anticoccidial vaccine and/or other vaccine. Alternatively, either method can be utilized without the subsequent vaccination step for stimulating non-specific cell-mediated immune responses in poultry.