DETERMINANTS OF AVIAN COCCIDIOSIS INFECTION AND PATHOGENICITY
Title: Gel-Bead Delivery of Eimeria Oocysts Protects Chickens Against Coccidiosis
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 10, 2011
Publication Date: June 28, 2012
Citation: Jenkins, M.C., Parker, C.C., Klopp, S., Obrien, C.N., Miska, K.B., Fetterer, R.H. 2012. Gel-Bead Delivery of Eimeria Oocysts Protects Chickens Against Coccidiosis. Avian Diseases. 56(2):306-309.
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. Anecdotal evidence indicates 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. Vaccine uptake and protection against Eimeria challenge infection was compared between gel bead-fed chickens and those immunized by standard spray vaccination. Vaccine uptake was 10- to 100-fold greater in gel bead-fed chickens compared to spray vaccine groups. Also, chickens that ingested Eimeria gel beads displayed higher and more uniform protection against coccidiosis compared to spray vaccinated chickens. These findings indicate that live Eimeria oocysts incorporated into gel beads may represent a significant improvement in the delivery of vaccines to chickens, and thereby reduce the incidence of avian coccidiosis in the poultry industry. A more effective coccidiosis vaccine will be beneficial to both poultry farmers and poultry companies by improving broiler and egg layer performance.
Vaccines composed of either virulent or attenuated Eimeria spp. oocysts have been developed as an alternative to medication of feed with ionophore drugs or synthetic chemicals. The purpose of this study was to evaluate the use of gel beads containing a mixture of E. acervulina, E. maxima, and E. tenella oocysts as a vaccine against coccidiosis. 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 (104 total) by oral gavage. After 3 days, chicks were randomly assigned to individual cages, and feces were collected between days 5-8 post-infection, and processed for total Eimeria oocysts. 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. Oocyst excretion by chicks fed gel-beads or inoculated by oral gavage was 10- to100-fold greater than chicks spray vaccinated with the Eimeria oocysts mixture (log 6.3-6.6 vs. log 4.8). Subsequent protection against challenge as measured by weight gain and feed conversion efficiency was significantly greater (P < 0.05) in gel-bead and oral gavage groups compared to spray vaccinated or non-immunized groups. Also, gel-bead and oral gavage groups showed no significant difference in weight gain and FCR compared to non-challenged controls (P> 0.05). These findings indicate that incorporation of Eimeria spp. oocysts in gel beads may represent an effective way to deliver live oocyst vaccines to day-old chicks for preventing subsequent outbreaks of coccidiosis in the field.