ABSTRACT
Robenidine protected chickens against cecal coccidiosis infections initiated by a strain of the parasite that had no previous exposure to drugs. No cross resistance was found with 13 strains resistant to other anticoccidials. A strain of Eimeria tenella that was serially propagated in chickens fed mash containing robenidine became resistant to the chemical. No cross resistance was detected when this experimental strain was tested against 12 other anticoccidials.
Subject(s)
Coccidiosis/parasitology , Eimeria/drug effects , Guanidines/pharmacology , Robenidine/pharmacology , Animals , Chickens , Coccidiosis/prevention & control , Coccidiostats/pharmacology , Drug Resistance, Microbial , Male , Robenidine/therapeutic useABSTRACT
Two nearly identical experiments were conducted to determine the effects of the coccidiostatic compound monensin on Polled Dorset lambs experimentally infected with oocysts of Eimeria ninakohlyakimovae. Prophylactic medication at a dose level of 1 mg/kg of body weight was started 2 days before inoculation and prevented diarrhea and reduced oocyst production. Therapeutic medication at a dose level of 2 mg/kg, started with the appearance of signs of infection, reduced oocyst production below that of nonmedicated controls but did not eliminate diarrhea. Weight gains of medicated lambs were less than those of noninoculated, nonmedicated controls in both experiments. Apparently monensin, at the dose levels used, reduced oocyst production but also prevented weight gains as high as those in inoculated nonmedicated controls.
Subject(s)
Coccidiosis/veterinary , Furans/therapeutic use , Monensin/therapeutic use , Sheep Diseases/drug therapy , Animals , Coccidiosis/drug therapy , Coccidiosis/parasitology , Feces/parasitology , Parasite Egg Count , Sheep , Sheep Diseases/parasitologyABSTRACT
A strain of the cecal coccidian of chickens, Eimeria tenella, was propagated serially in chickens fed mash containing amprolium, nicarbazin, Unistat, or zoalene. Each group of chickens received a different coccidiostat on a rotating basis. The strain was propagated through 40 groups of chickens; thus, the strain was intermittently exposed 10 times to each coccidiostat. The end product of this simulated shuttle program of prophylactic anticoccidial medication was a strain resistant to three of the four coccidiostats involved. Resistance to nicarbazin was not evident.
