Effects of administration of tylosin on the duration of protective immunity induced by the novel Mycoplasma gallisepticum vaccine strain, Vaxsafe MG ts-304, in chickens

Abstract

Prophylactic use of antimicrobials after administration of live vaccines is a common practice in the poultry industry, but the impact of this on the efficacy and duration of protection induced by the vaccines is unknown. The effect of treatment with tylosin on the efficacy of vaccination with the live attenuated M. gallisepticum strain, Vaxsafe MG ts-304, was examined. This vaccine has previously been shown to provide protection for at least 57 weeks. Ten-week-old specific-pathogen-free chickens were vaccinated with Vaxsafe MG ts-304 and then treated with tylosin at a therapeutic dose in drinking water from 6 weeks after vaccination. Tylosin was withdrawn 5 days before challenge with M. gall..