Effects of the in ovo administration of the 6/85 Mycoplasma gallisepticum vaccine on layer chicken embryo hatchability and early posthatch performance

Authors: ALQHTANI, A - Mississippi State University; FATEMI, S - Mississippi State University; Collins Elliott, Katie; BRANTON, SCOTT - Retired ARS Employee; Evans, Jeffrey - Jeff; PEEBLES, E - Mississippi State University

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/2023
Publication Date: 3/31/2023
Citation: Alqhtani, A.H., Fatemi, S.A., Collins Elliott, K.E., Branton, S.L., Evans, J.D., Peebles, E.D. 2023. Effects of the in ovo administration of the 6/85 Mycoplasma gallisepticum vaccine on layer chicken embryo hatchability and early posthatch performance. Animals. 13(7):1228. https://doi.org/10.3390/ani13071228.
DOI: https://doi.org/10.3390/ani13071228

Interpretive Summary: Vaccines are widely relied upon to protect poultry against pathogens and their associated production losses. The development of safe and efficient vaccine delivery protocols can increase both the rate of utilization and the protection afforded by the vaccine. Application of vaccines to poultry prior to hatch is an efficient means of vaccination which has been successfully applied to numerous viral-based vaccines. Bacterial-based vaccines which protect against bacterial pathogens are rarely applied prior to hatch. In this study, a vaccine against the bacterial poultry pathogen Mycoplasma gallisepticum were developed and investigated. The vaccination of poultry prior to hatch with the Mycoplasma gallisepticum vaccine reduced chick hatchability when applied at high levels, however when applied at lower concentrations, only minimal impacts of the vaccination were observed. Further research is needed to examine the influence of the Mycoplasma gallisepticum vaccine delivered prior to hatch on layer immune competence.

Technical Abstract: In ovo administration as a possible alternative method of 6/85MG vaccination was assessed. On 18 d of incubation (doi), the eggs were administered a particular dosage of a live attenuated 6/85MG vaccine in either the air cell (AC) or amnion (AM). The treatments included non-injected eggs and eggs injected in the AC or AM with diluent alone as controls. Treatments also included eggs injected with diluent containing 1.73, 102, or 104 CFU of 6/85MG. On d 21, 6 birds per treatment replicate were swabbed and bled. Hatchability of viable injected eggs (HI) and residual embryonic mortality were determined at 22 doi. One hatched chick per treatment replicate was bled and swabbed for the detection of 6/85 MG in the choanal cleft using PCR, serum plate agglutination (SPA) and ELISA methods. The 1.73 × 104 6/85MG CFU dosage in the AM group decreased HI and was associated with a significant increase in late dead mortality. The hatchling and 3-week-old chick mortalities were greater in 1.73 × 104 CFU-AM treatment group in comparison to all other treatment groups. In addition, the 6/85MG-AM was more effective than 6/85MG-AC in protection of pullets against MG. Furthermore, the medium and higher dose of AM treatment groups resulted in greater protection, but the higher dose (1.73 × 104 CFU-AM) treatment group adversely influenced chick HI and posthatch survival. Further research is needed to examine the influence of the 6/85MG in ovo vaccine on layer immune competence.