Research note: immunity to Eimeria in broilers reared on nicarbazin and salinomycin

Area of Science:

• Poultry Science
• Veterinary Parasitology
• Animal Health

Background:

• Coccidiosis, caused by Eimeria parasites, is a significant concern in broiler production.
• Shuttle programs using anticoccidial drugs like nicarbazin and salinomycin are common for disease control.
• Assessing the development of host immunity is crucial for sustainable parasite management.

Purpose of the Study:

• To evaluate the development of immunity to Eimeria species in broiler chickens.
• To determine the efficacy of a drug shuttle program in inducing protective immunity.
• To compare immunity levels against different Eimeria species across two commercial farms.

Main Methods:

• Monitoring oocyst incidence in litter from two broiler farms over 8 weeks.
• Administering a shuttle program with nicarbazin (0-21 days) and salinomycin (21-44 days).
• Challenging birds with three Eimeria species (E. acervulina, E. maxima, E. tenella) to assess immunity via weight gain and oocyst production.

Main Results:

• Oocysts of at least three Eimeria species were detected in low numbers in the litter.
• Birds from both farms demonstrated immunity to Eimeria acervulina and Eimeria maxima, evidenced by weight gain.
• Incomplete immunity was observed, as indicated by oocyst shedding, particularly against E. acervulina and E. maxima.
• One farm exhibited immunity to Eimeria tenella, while the other remained susceptible.

Conclusions:

• The anticoccidial drug shuttle program conferred partial immunity against key Eimeria species in broiler chickens.
• Immunity levels varied significantly between different Eimeria species and between the two farms studied.
• Further research is needed to optimize drug programs for complete and consistent immunity against coccidiosis.