[Dynamics of the incidence of coccidiosis in chickens in relation to the level of anticoccidial care].

The incidence of coccidiosis was evaluated in pullets and broilers raised in large--scale conditions. We confirmed a relationship between the extensity and intensity of coccidium incidence on the one hand and the content of anticoccidic drugs in feed mixtures and the husbandry standard on poultry farms on the other. We studied the causes of failure of the efficiency of the anticoccidic drug Amprol Plus after a short time of its administration to the fowl and we demonstrated a resistant strain of the field isolate of Eimeria tenella in connection with low doses of this anticoccidic drug in feed mixtures.