Abstract: Effective immunity against coccidiosis can be imparted to poultry if the birds are reared on a regular diet containing added viable sporulated coccidia oocysts at a level sufficient only to induce sub-clinical infection. Preferably the oocyst-containing diet is presented to the birds as soon as they are able to ingest solid food, and contains from 10 to 10,000 oocysts per kg of nutrient feed material. The simultaneous administration of an anti-coccidial drug at a curative level can help to control the immunity-producing infection. The oocyst-containing feedstuff of the invention can be prepared using solid free-flowing pre-mixes or aqueous concentrates, containing appropriate numbers of oocysts together with edible thickening agents. The oocysts can be protected against loss of viability through dehydration by being encapsulated. Growth of the immunized birds is sustained even when they are exposed to a severe oocyst challenge sufficient to induce serious infection in unimmunized birds.

Abstract: Effective immunity against coccidiosis can be imparted to poultry if the birds are reared on a regular diet containing added viable sporulated coccidia oocysts at a level sufficient only to induce sub-clinical infection. Preferably the oocyst-containing diet is presented to the birds as soon as they are able to ingest solid food, and contains from 10 to 10,000 oocysts per kg of nutrient feed material. The simultaneous administration of an anti-coccidial drug at a curative level can help to control the immunity-producing infection. The oocyst-containing feedstuff of the invention can be prepared using solid free-flowing pre-mixes or aqueous concentrates, containing appropriate numbers of oocysts together with edible thickening agents. The oocysts can be protected against loss of viability through dehydration by being encapsulated. Growth of the immunized birds is sustained even when they are exposed to a severe oocyst challenge sufficient to induce serious infection in unimmunized birds.