Eimeria tenella in chickens: Studies on resistance to the anticoccidial drugs monensin and lasalocid |
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| Authors: | HD Chapman |
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| Institution: | Houghton Poultry Research Station, Houghton, Huntingdon, Cambs, Great Britain |
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| Abstract: | The response of the Houghton strain of E. tenella to monensin and lasalocid is described. Neither drug was able to completely control this strain at 125 ppm. At this concentration oocyst production was not completely suppressed by monensin in birds given ten oocysts. At higher concentrations both drugs were able to control E. tenella (H) in birds given 1 × 105 oocysts but monensin was toxic. 375 ppm monensin did not prevent oocyst production in birds given 4 × 106 oocysts. Resistance could not be developd to either of these compounds after 12 serial passages in the presence of drug. Serial passage of E. tenella (H) in the presence of monensin however resulted in an increase in pathogenecity. This greater pathogenecity was not due to a better ability to multiply in the host. |
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