Submitted to: Coccidiosis International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/30/2005
Publication Date: 9/15/2005
Citation: Jenkins, M.C., Klopp, S., Wilkins, G.C., Miska, K.B. 2005. Comparison of drug-sensitivity and species composition of eimeria isolated from poultry farms utilizing either anti-coccidial drugs or a live oocyst vaccine to control avian coccidiosis. Coccidiosis International Conference Proceedings. p.42 Interpretive Summary:
Technical Abstract: The purpose of this study was to compare drug resistance and species composition of Eimeria isolated from two types of poultry operations that differed in the means of controlling avian coccidiosis (i.e. drugs vs. live oocyst vaccine). Poultry litter was collected from 10 different broiler operations; 5 utilizing anti-coccidial drugs, 5 utilizing a live oocyst vaccine. The number of species present in vaccine-control facilities was greater than in drug-control operations, with all 6 species present in the former, and 3-4 species present in the latter. The pathogenicity of oocysts propagated from the vaccine-using farms was greater than in the drug-utilizing farms, in that 3.5 times fewer oocysts were needed to cause similar levels of weight depression. Eimeria propagated from drug-utilizing operations displayed greater anti-coccidial resistance, as measured by lower weight gains, higher intestinal lesion scores, and poorer feed conversion ratios, compared to Eimeria recovered from farms using a live oocyst vaccine. Only one drug, Avatec, provided greater than 90% weight gain protection against coccidiosis in broilers challenged with oocysts recovered from drug-utilizing farms. In contrast, three drugs-Coban, Biocox, and Avatec, provided greater than 90% protection against challenge with oocysts recovered from vaccine farms. Quite unexpected was the partial resistance to two drugs, Clinicox and Monteban, observed in oocysts isolated from vaccine-using farms. These results suggest that conventional drug treatment leads to lower Eimeria species diversity coincident with slightly greater drug resistance. The mechanism by which non-vaccine drug-resistant species are introduced into vaccine-utilizing farms remains to be determined.