Oocyst-shedding pattern determined in turkeys vaccinated for coccidiosis

Peak oocyst-shedding patterns have been determined for turkeys vaccinated with a live coccidiosis vaccine and can be used as a reference in the field, Dr. Greg F. Mathis said at the World’s Poultry Conference, held this summer in Brisbane, Australia.

If turkeys are to develop immunological protection against coccidiosis, oocyst cycling is vital. All poults must at some time receive adequate and repeated numbers of the various species of Eimeria oocysts that cause disease in turkeys, explained Mathis, of Southern Poultry Research in Athens, Georgia.

Oocyst-shedding patterns, which are a good indicator of coverage and immunity development, were evaluated by Mathis in turkeys that were either sprayed or orally dosed on day of hatch with Coccivac-T live turkey coccidiosis vaccine.

In birds sprayed with the vaccine, the major peak in oocysts pergram (OPG) of feces occurred at 15 to 18 days and, in orally dosed birds, at 6 to 8 days. Spray-vaccinating birds is more convenient for the hatchery than individually dosing birds but takes somewhat longer to achieve 100% coverage.

Nevertheless, in both groups, the peaks in OPG were followed by a decline in OPG, indicating that coverage was adequate to induce substantial coccidial immunity and reduce the number of parasites reproducing within the birds.

“This epidemiological information can be used as a reference for field levels of oocysts in vaccinated turkey houses,” Mathis said.