Oksidativni stres kod tovnih pilića inficiranim vrstama parazita roda Eimeria nakon primene kokcidiostatika
Despite remarkable advances in management, technology, diet and therapy, coccidiosis remains one of the major diseases in intensive poultry production. It has been detected that in chickens infected with coccidia significant changes in the parameters of oxidative stress develop, which is a consequence of a disbalance between the production of reactive oxygen species (ROS) and antioxidants. The aims of this research were: 1) investigation into the influence of two different types of anticoccidials (robenidine and Herbakoks) on the oxidative stress in broiler chickens infected with Eimeria, 2) determination of Eimeria species which parasitize broiler chickens with molecular techniques (PCR), 3) assessment of the prevalence of sub-clinical infection on broiler farms, and 4) detection of possible association between biosecurity measures on chicken farms and the emergence of subclinical and clinical coccidial infections. To assess the effect of anticoccidials on fattening chickens, five experimental groups were established: two untreated (uninfected and infected) and three treated with anticoccidials (all infected with Eimeria spp.). One of the treated groups was administered robenidine (Ro), the second the herbal anticoccidial Herbakoks (Herb), аnd the third one - the combination of robenidine and Herbakoks (Ro+Herb). All infected groups were inoculated orally with Eimeria oocysts (mixed infection) on day 14 after hatching. The blood was sampled on days 12, 21 and 40 and the activities of catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST) and the concentration of the product of lipid peroxidation - malondialdehyde (MDA) - determined. The number of oocysts per gram of faeces, chicken body weight and feed conversion ratio (FCR) were also measured. Eimeria species detected in broiler chickens were determined using PCR assay. The data on biosecurity measures were obtained in a questionnaire which was filled in when the faeces samples were collected on broiler farms. The activities of CAT and GST, as well as the level of MDA decreased, but the activity of SOD increased in treated groups of chickens in comparison with untreated infected, which suggests that the anticoccidials may decrease the oxidative stress. The most notable changes in the parameters of oxidative stress were detected in the Ro+Herb group. The body weight of chickens treated with anticoccidials was significantly higher, аnd their FCR and oocyst counts significantly lower in comparison with the uninfected untreated chickens. Oocyst counts were lower in Ro and Ro+Herb group in comparison with Herb group. These results suggest that synthetic anticoccidial drug and the combination of the two lead to better effect in coccidiosis prevention than the herbal one, but was proven that it can also be used in coccidiosis prevention. On 59% broiler farms Eimeria oocysts were detected. The infection was sub-clinical on 51% of farms monitored, аnd clinical on 8%. PCR technique detected four Eimeria species: E. acervulina (37%), E. maxima (17%), E. mitis (25%) and E. tenella (48%). The imposed measures of disinfection, disinsection and rodent control, as well as all biosecurity measures considered together may significantly influence the prevention of coccidiosis.