Live anticoccidial vaccines in the poultry industry: current knowledge, global strategies, technical foundations and future directions.

The use of live anticoccidial vaccines has increased in the poultry industry in recent years. Historically, these vaccines have been widely used in breeders due to their suitability for long life production cycles. In contrast, their use in short-lived birds was traditionally limited, but this trend has changed significantly. This shift is mainly driven by the growing demand for antibiotic-free production systems (e.g. No Antibiotics Ever (NAE) or Raised Without Antibiotics (RWA) broiler production) and increasing resistance to anticoccidial drugs. The success of live vaccination depends largely on the method of administration and the homogeneous distribution of sporulated oocysts, both of which require careful management to ensure uniform coverage and early intestinal replication in the majority of chicks. Three vaccination strategies are commonly used in broiler production: vaccination as the sole preventive measure; incorporation of vaccines into rotation programmes that alternate with anticoccidials; and combined use of vaccines and anticoccidials within the same flock (bio-shuttle programmes). Future developments in the use of live anticoccidial vaccines are expected to be influenced by several factors, including changes in husbandry practices, expansion of the global poultry market, improvements in vaccine formulations, advancements in the knowledge of host immunity, and innovations in vaccine production. These evolving factors will shape both the design and application of vaccination strategies in the coming years.