This study was designed to provide a rapid highly protective passive immunization of chickens against necrotic enteritis
(NE). This aim was established by preparation of NE alpha toxin IgY in chicken egg yolk, such preparation was found to
have specific anti NE alpha toxin titer 40 I.U by SNT and 0.237 optical density (OD) by ELISA. It was found that oral
administration of 40, 20, 10 and 5 IU/ml of IgY / poult after experimental infection with Clostridium perfringens type
A, resulted in protective rates of 96%, 88%, 80% and 60% respectively. Chickens' sera of passively immunized birds
showed antibody titers of 1, 2 and 1.5 I U in the first, second and third days' post immunization respectively. It was
concluded that IgY for NE alpha toxin type A could be used successfully to protect or even minimize the severity of the
disease during possible outbreaks