Effectiveness of therapeutic anticoccidial drugs against recently isolated coccidia

Litter samples were collected weekly from 17 broiler houses and coccidial oocysts were counted. Oocysts per gram were low on the Weeks 1 and 2 of the growout, increased to a peak on the Week 4, then declined to near zero on Weeks 6 and 7. Coccidia from each house were propagated and tested for sensitivity to therapeutic formulations of amprolium, sulfaquinoxaline, and sulfaquinoxaline plus pyrimethamine. The degree of control was based on the weight gains and lesion scores of the medicated groups in comparison with those of the unmedicated, infected, and uninfected groups. The predominant species found in the 17 isolates were Eimeria tenella and E. acervulina. Amprolium was effective against E. tenella in all isolates but only partly effective against E. acervulina. Sulfaquinoxaline and the potentiated mixture were effective against the E. acervulina but only partly effective against the E. tenella. The potentiated mixture was better against E. tenella than sulfaquinoxaline alone.