Evaluation of the potential influence of the disinfection cycle on the efficacy of strain F Mycoplasma gallisepticum vaccine administered by in ovo injection to layer hatching eggs

In ovo administration of a live-attenuated F-strain Mycoplasma gallisepticum vaccine (FMG) has proven to be a promising alternative vaccination route for layer chickens to combat M. gallisepticum (MG) infections. Its practical application within current in ovo vaccination procedures, employing a disinfection step after each injection, has been uncertain. The objective of this experiment was to determine the ability of FMG to survive the in ovo disinfection step to elicit a posthatch immune response. In 2 trials, layer eggs were in ovo-vaccinated with or without the disinfection step between injections. Utilizing an Embrex Inovoject M machine, treatments included noninjected eggs, diluent-injected eggs with or without a disinfection step, and eggs vaccinated with an FMG vaccine with or without a disinfection step. Ninety hatched chicks per treatment in both trials were raised to 6 wk of age and swabbed in the choanal cleft for FMG detection via PCR and were bled for IgM (serum plate agglutination) and IgG (ELISA) testing for detection of antibody production against MG. The percentage of birds in which FMG was detected at 6 wk of age were similar among both FMG vaccination treatments in both trials (overall 89.4% without and 91.6% with disinfectant step). Birds vaccinated with FMG also developed antibody responses regardless of employment of the disinfection step. These results indicate that FMG survives the disinfection step employed by commercial machines and can be readily applied to current commercial procedures of in ovo vaccination with no detriment to vaccine efficacy.