Toxicity and Acquisition of Immunity to Coccidia in Turkeys Medicated with Anticoccidials

Abstract

Two studies examined toxicity and the development of acquired coccidial immunity when using anticoccidials. The studies examined two ionophorus anticoccidials, monensin and lasalocid and two chemicals, halofuginone and amprolium.In the toxicity study, 16 week old tom turkeys that had never been exposed to anticoccidials were fed the test anticoccidials at the recommended or twice the recommended use levels. The ionophore salinomycin, typically fed to chickens, was also tested at 66 ppm. Salinomycin was found to be toxic, producing greater than 50% mortality and a 45% suppression in weight gain compared to non-medicated controls. No mortality was produced with any of the other products. At twice the recommended level of the ionophores monensin and lasalocid, there was a significant (P < .05) suppression in percent weight gain compared to non-medicated controls.Immunity in the context of this research is measured in protection from coccidial challenge. This study used an immunizing dose of mixed Eimeria species given to turkeys at 10 days of age. The effect of the test anticoccidials on acquisition of coccidial immunity was determined by challenge inoculation at 10 weeks of age, 1 day after all medications were removed. All anticoccidials allowed some immunity development as indicated by significantly (P < .05) higher weight gains, less coccidial lesions, and fewer oocyst shed compared to the non-medicated non-immunized challenged controls. Significant lower weight gains and higher oocyst shedding occurred with the turkeys fed halofuginone (3 ppm) for the 10 week period than with the turkeys fed with the other anticoccidials, indicating limited oocyst cycling due to stronger coccidial control.