A COMPARISON OF DANOFLOXACIN AND TYLOSIN IN THE CONTROL OF INDUCED MYCOPLASMA-GALLISEPTICUM INFECTION IN BROILER CHICKS

Experimental mycoplasmosis was induced in 1-day-old chicks by intrapul monary inoculation of Mycoplasma gallisepticum (MG). This method of in fection proved to be useful for evaluating the efficacy of antimicrobi al medication, by measuring mortality, weight gain, pathological respo nses, frequency of reisolation of MG, and seroconversion. Using this m odel, the efficacies of danofloxacin (2 novel fluoroquinolone) and tyl osin were compared for two MG isolates, a reference isolate (the R-str ain) and 2 field isolate from California. Danofloxacin administered in the water at 50 ppm for 3 days was equivalent to tylosin at 500 ppm f or 3 days in the degree of control of mortality and maintenance of wei ght gain. Danofloxacin was superior to tylosin in preventing air-sac l esions, reducing the frequency of reisolation of MG, and preventing se roconversion in surviving birds.