EFFECT OF AMPROLIUM ON PRODUCTION, SPORULATION, AND INFECTIVITY OF EIMERIA OOCYSTS

Amprolium reduced the number of oocysts shed by Eimeria acervulina, E. maxima, E. necatrix, and a mixture of susceptible strains of E. tenel la. Sporulation of oocysts from medicated chickens was reduced compare d with that of oocysts from unmedicated chickens. Sporulation was redu ced by levels of 0.0250% amprolium for E. acervulina and by levels of 0.0060% for E. maxima and the susceptible E. tenella. Not enough oocys ts were recovered to measure sporulation of E. necatrix. Sporulation r eduction was not affected by the method of administration of amprolium (feed or water), except with E. acervulina, for which fewer oocysts s porulated when 0.0120% amprolium was added in the drinking water than when 0.0125% amprolium was added to the feed. Conversely, amprolium me dication had no effect on the sporulation of an amprolium-resistant E. tenella. When fed to unmedicated chickens, those oocysts from amproli um-medicated chickens that did sporulate were as infective as oocysts recovered from unmedicated chickens.