1978 Volume 31 Issue 10 Pages 592-596
Monensin is a biologically active compound produced by Streptomyces cinnamonensis. Chicks were administered continually with monensin at a level of 240 ppm in feed, the highest concentration tested. An almost complete preventive effect was seen against infections with Eimeria tenella, E. acervulina, E. maxima, and E. brunetti, judging from the lesion scores and counts of oocysts reproduced. Sufficient growth rates were obtained from chicks medicated with 120 ppm of monensin in feed. Culture media containing monensin in various concentrations were added to BHK 21 cell cultures, to which E. tenella sporozoites were inoculated. A complete inhibitory effect was demonstrated against the development of organisms at a level of 0.001 ppm (10-9) of the drug added to the culture medium. Effective anticoccidial activity against E. tenella was observed when the drug was administered at 120 ppm for chicks and at 0.001 ppm for BHK 21 cell cultures within 24 hours after inoculation. Monensin was highly effective in early developmental stages of coccidia.