Efficacy of buquinolate in chickens inoculated with drug-sensitive and drug-tolerant coccidial species

In two battery trials, chickens fed various levels of buquinolate were inoculated with susceptible coccidia (Eimeria acervulina, E. brunetti, and E. necatrix) and a drug-tolerant isolate of E. tenella. In trial I, chickens medicated with 0.00825% buquinolate were inoculated initially with the intestinal species and given the E. tenella 2, 4, or 6 days later. No clinical coccidiosis resulted from the intestinal species even in the face of moderate to severe infection with the drug-tolerant isolate. These results were confirmed in a second trial when buquinolate-medicated chickens (0.0055, 0.00825, and 0.011%) were administered the susceptible species and inoculated 4 days later with the drug-tolerant E. tenella isolate. From both trials it appears that the normal sloughing of parasitized host cells containing arrested (but viable) asexual stages of the intestinal species contributed significantly to the similarity in efficacy of the three levels of buquinolate.