| Avian coccidiosis is one of the serious infectious diseases of poultry caused by different species of genus Eimeria spp, and the Eimeria tenella is the most common with the most pathogenicity to chickens. Poultry farmers mainly rely on the prophylactic and therapeutic use of chemicals for the control of avian coccidiosis. Frequent usage of anticoccidialstats, however, has resulted in the development of resistance in the Eimeria species. So it is necessary to provide the reasonable medication program for controlling chicken Eimeria tenella. The combination method of coccidiostats, through the synergistic effect between them, can delay the emergence of drug resistance, and can obtain corresponding results with less dosage.In this research, the third-generation merozoites of E. tenella were isolated and used to evaluate the potential mechanism of artemisinin. We investigated the anticoccidial efficacy of the combination of artemisinin (ART) and Antibacterial Synerists against coccidiosis induced by E. tenella. And then, we found the best dosage and the synergistic effect when ART combined with DVD. The results will improve the rational use of anticoccidial drugs to reduce or avoid drug resistance or other issues.1. To evaluated the potential mechanism of artemisinin action on the third-generation merozoites of E.tenella. At 156h after inoculation by oral E.tenella sporulated oocysts, we collected the third-generation merozoites of E.tenella from the chicken's cecum in different groups. Apoptosis and mitochondrial transmembrane potential (MMP) were determined by flow cytometry (FCM). Ultra structural changes were monitored by transmission electron microscopy (TEM). The results showed that compared with the challenge control group, artemisinin excerted an extremely significant reduction in mitochondrial transmembrane potential by 47.06% (P<0.05), and increased the apoptotic rate by 230% (P<0.01) in third-generation merozoites, respectively. Ultra structural analysis showed that merozoite'volume was reduced with increased the density of the cytoplasm, chromatin condensation, in addition, heterochromatin was becoming more apparent marginalization. In conclusion, artemisinin accelerated the apoptosis of the third-generation merozoites of E.tenella.2. In order to explore the synergistic effect of ART and DVD on poultry coccidiosis induced by E.tenella. Daily observed and recorded the clinical symptoms of chickens after inoculation E.tenella, calculated anticoccidial index (ACI) by the relative weight gain rate, survival rate, bloody feces, lesion scoring and the number of oocysts per gram (OPG). At the end of the test, gross anatomy was done on chickens from every groups, then the HE staining hispathologic slide of cecum was made. The pathological structural changes of chicken cecal tissue were observed by scanning electron microscopy. The results showed that ACI of the combination group was more than 180. The epithelial cells of cecum slightly destroyed and the smooth muscle of cecum did not thicken or only kind of thicken. When the ART dose was 50 ppm/d, the dosage of DVD was 40 ppm/d, the effect of combined application was the best. The serum biochemical parameters had no significantly different among the groups, indicating that the combination of two medicines had no obvious toxicity to chicken livers and kidneys. In conclusion, there were obvious synergistic effect between Artemisinin and Diaveridine. |
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