Kinichi Imai

Eimeria tenella, E. necatrix, E. acervulina, and E. maxima: anticoccidial activity of 1,6-dihydro-6-oxo-2-pyrazinecarboxylic acid 4-oxide

The anticoccidial activity of an orotic acid analog, 1,6-dihydro-6-oxo-2-pyrazinecarboxylic acid 4-oxide (carboxyemimycin), was tested in battery experiments, utilizing 9-day-old Single-Comb White Leghorn cockerels. Carboxyemimycin, at 125 ppm and more in feed, exhibited marked anticoccidial activities against Eimeria tenella, E. necatrix, E. acervulina, and E. maxima. High doses of carboxyemimycin--up to 1000 ppm--did not cause any reduction in weight gains. The battery and in vitro studies with delayed and restricted medications revealed that carboxyemimycin affected the development of E. tenella in first and second generation schizogony and in gametogony.

Eimeria tenella, E. necatrix, E. acervulina, E. maxima, and E. brunetti: Potent anticoccidial activity of an uridine analog, 1-(β-d-ribofuranosyl)-2(1H)-pyrazinone 4-oxide

The anticoccidial activity of an uridine analog, 1-(beta-D-ribofuranosyl)-2(1H)-pyrazinone 4-oxide (emimycin riboside), against five species of chicken Eimeria was tested individually in battery experiments. With 16 ppm of the compound in feed, marked anticoccidial activity was obtained against Eimeria tenella, E. necatrix, E. acervulina, E. maxima, and E. brunetti. The last named species was more drug-sensitive than the others--dietary levels of at least 8 ppm of the drug exhibited good protection and eliminated practically all clinical signs. The battery tests with delayed and restricted medications showed that emimycin riboside affected the development of parasites in first and second generation schizogony of the life cycle of E. tenella.