Location: Animal Parasitic Diseases
Title: Increased efficacy of Eimeria oocysts delivery by gel beads or spray vaccination Authors
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 17, 2013
Publication Date: N/A
Interpretive Summary: Avian coccidiosis is an intestinal disease of poultry caused by protozoa in the genus Eimeria. Coccidiosis outbreaks are controlled by either medication of poultry feed with anti-coccidial drugs or vaccination of day-old chicks with low doses of live Eimeria oocysts. Studies have shown that current methods of delivering live oocyst vaccines to chicks are inefficient, and as a result a significant proportion of chicks remain fully susceptible to disease once placed in the poultry house. In the present study, laboratory strains of Eimeria oocysts were incorporated into gelatin beads, which were fed to day-old chicks via poultry feed. The chicks were housed in floor pens to replicate a typical poultry house. Vaccine uptake and protection against Eimeria challenge infection was compared between gel bead-fed chickens and those immunized by standard spray vaccination. Chickens vaccinated using gel beads or spray delivery displayed excellent weight gain and improve feed conversion efficiency over the infection period. These findings indicate that live Eimeria oocysts incorporated into gel beads or sprayed as an aqueous solution is an effective way to vaccinate chickens against coccidiosis in a poultry house. A more effective coccidiosis vaccine will be beneficial to both poultry farmers and poultry companies by improving broiler and egg layer performance.
Technical Abstract: Control of avian coccidiosis is increasingly being achieved by the administration of low doses of Eimeria oocysts to newly hatched chicks. The purpose of this study was to test the efficacy of gel-beads containing a mixture of E. acervulina, E. maxima, and E. tenella oocysts as a vaccine to protect broilers raised in contact with litter. Newly hatched chicks were either sprayed with an aqueous suspension of Eimeria oocysts or were allowed to ingest feed containing Eimeria oocysts-incorporated gel-beads. Control day-old chicks were given an equivalent number of Eimeria oocysts (103 total) by oral gavage or received no vaccine (non-immunized controls). All chicks were raised in floor-pen cages in direct contact with litter. At 4 weeks of age, all chickens and a control non-immunized group received a high dose E. acervulina, E. maxima, and E. tenella challenge infection. Chickens immunized with Eimeria oocysts in gel beads or by spray vaccination displayed significantly (P < 0.05) greater weight gain (WG) compared to non-immunized controls. Feed conversion efficiency (FCR) also showed a significant (P < 0.05) improvement in both groups relative to non-immunized controls. Moreover, WG and FCR in both groups was not significantly different (P > 0.05) from chickens immunized by oral gavage or from non-immunized non-infected controls (NINC). Oocyst excretion after Eimeria challenge by all immunized groups was about 10-fold less than non-immunized controls. These findings indicate that vaccination efficacy of gel beads and spray vaccination is improved by raising immunized chicks in contact with litter.