Opornosc kokcydii Eimeria tenella na kokcydiostatyki stosowane aktualnie w hodowli drobiu

Evaluation of coccidia resistance to Amprol plus, Lasalocid and monensin was carried out on two weeks old chickens infested experimentally with 100 000 oocysts per bird. Coccidiostatics for prophylactic purposes (Amprol plus — 133 ppm, Lasalocid — 75 ppm, monensin — 100 ppm) were given in feed 48 hours before infestation and then for 8 days after infestation. Sensitivity of 30 strains of E. tenella was assessed on the basis of anti-coccidiostatic index, i.e. total percentage of alive chickens and per cent of weight gains minus pathological gross index and oocyst index. The heighest mean values of anti-coccidiostatic index was reached following the Lasalocid administration (x =189.2) and the lowest one after the monensin application (x = 127.3). The studies revealed that 11 strains of coccidia were of a lowered sensitivity to Amprol plus, 10 to Lasalocid and 15 to monensin. Besides, it was found that 8 strains of E. tenella had a lowered sensitivity to the three coccidiostatics applied.