injection of turkey hatching eggs with tylosin to eliminate Mycoplasma meleagridis infection

Turkey embryos were found to be sensitive to injected tylosin. This limited the dose to 1 mg or less per egg when the drug was injected into the air cell prior to incubation. Initial assay studies indicated that tylosin persisted in the egg throughout the incubation period and was detected in the yolk of the hatched poult. In 4 trials in which 2.5 to 5 mg of tylosin was injected into embryonating eggs at various times during incubation, none resulted in poults free of Mycoplasma meleagridis. Twelve additional trials were done in which tylosin was injected prior to incubation. In 6 (dose 0.5 to 1 mg), poults hatched from the injected eggs remained free of infection to 5 weeks. In the other 6 trials the infection was not eliminated.