Abstract

Coccidiosis is the most common protozoan disease in poultry and is often recorded in poultry farms with the free-range system. The share of such poultry farms is constantly growing in Russia. The present study designed an experimental model of coccidiosis induced by Eimeria tenella in broilers. Forty-two 14-days-old broilers of the cross "ABH 47" were divided into seven groups of six broilers each according to the principle of analogs. Broilers were weighed at the beginning and at the end of the experiment. The groups were kept isolated throughout the study. Chickens in groups 1, 2, 3, 4, 5 and 6 were orally infected with E. tenella culture at the doses of 2,000; 1,000; 250; 125; 62 and 15 oocysts/ml, respectively. Broilers of group 7 were uninfected and served as control. To determine the number of oocysts, all feces from the broilers of each experimental group were daily collected from the days 6 to 12 after infection. Counting was carried out using the McMaster technique. The average number of E. tenella oocysts per gram of feces in broilers of the groups 1 to 6 was 4,080; 6,880; 1,780; 1,530; 662 and 94, respectively. The average daily weight gain in groups 1 to 4 was significantly lower compared to the non-infected control group. The experimental model of coccidiosis in broiler chickens revealed that the number of oocysts excreted with feces is dependent on the dose of infection.