POTENTIATION OF IONOPHOROUS ANTICOCCIDIALS WITH DUOKVIN - BATTERY TRIALS AGAINST CRYPTOSPORIDIUM-BAILEYI IN CHICKENS

Three battery tests, employing 444 Arbor Acres chickens, were conducte d to study the anticryptosporidial efficacy of the polyether ionophoro us anticoccidials alone and in combination with a new dihydroquinoline antioxidant, duokvin. The following efficacy percentages for the iono phores at the recommended level were established on the basis of oocys t output: lasalocid 45, monensin 37, semduramicin 29, narasin 23, and maduramicin and salinomycin 21. The efficacy of the ionophores, with t he exception of lasalocid, could be increased to 36-88% by combination with duokvin. However, these combinations resulted in a significant w eight gain reduction due to toxic interaction. Efficacy showed a stron g negative correlation with body weight gain and bursa weight, suggest ing an indirect mode of action against the parasite. It has been concl uded that neither ionophorous anticoccidials nor their combinations wi th duokvin can be recommended for chemoprophylaxis against avian crypt osporidiosis.