Variable effects of the in ovo administration of an Escherichia coli vaccine in the amnion or air cell on commercial layer embryo and hatchling development

Authors: LINDSEY, L - Mississippi State University; Collins Elliott, Katie; FRATEMI, S - Mississippi State University; Evans, Jeffrey - Jeff; MOUSSTAAID, A - Mississippi State University; GERARD, P - Clemson University; PEEBLES, E - Mississippi State University

Submitted to: Poultry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2022
Publication Date: 12/8/2022
Citation: Lindsey, L.L., Collins Elliott, K.E., Fratemi, S.A., Evans, J.D., Mousstaaid, A., Gerard, P.D., Peebles, E.D. 2022. Variable effects of the in ovo administration of an Escherichia coli vaccine in the amnion or air cell on commercial layer embryo and hatchling development. Poultry. 1(4):278-290. https://doi.org/10.3390/poultry1040023.
DOI: https://doi.org/10.3390/poultry1040023

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 means to apply vaccine against the bacterial poultry pathogen Avian Pathogenic Escherichia coli (APEC) prior to hatch were developed and investigated. Two sites of vaccine deposition were comparted. The vaccination of poultry prior to hatch with the APEC vaccine in the amnion consistently resulted in vaccine derived populations within the hatchlings. However, these vaccine delivery methods (particularly those with high dosages) could reduce chick hatchability, however when applied at lower concentrations, only minimal impacts of the vaccination were observed. Further research is needed to examine the influence of the APEC vaccine delivered prior to hatch on layer immune competence.

Technical Abstract: In layers, an avian pathogenic E. coli (APEC) infection can cause significant economic loss to the table egg industry. The Poulvac E. coli vaccine (PECV) is a common E. coli vaccine for flock protection against APEC. The administration of PECV by in ovo injection has not been previously tested. The purpose of this experiment was to determine the effects of site of injection [air cell (AC) and amnion (AM)] within different dosages of the PECV at 18 days of incubation (DOI) on Hy-Line W-36-layer embryo and hatchling development. Serial dilutions of the PECV in diluent provided either 6.5 x 104, 6.5 x 103, 6.5 x 102, or 6.5 x 101 CFU dosages of E. coli. At 19 DOI, swabs of the AM indicated that the 6.5 x 101 and 6.5 x 102 CFU dosages provided a 50% level of PECV presence, whereas the 6.5 x 103 and 6.5 x 104 CFU dosages provided a 100% level of PECV presence. Conversely, only the 6.5 x 103 and 6.5 x 104 CFU dosages provided a 50% level of PECV presence in the AC. At all E. coli dosage levels, injection in the AM led to higher percentages of live or dead embryos that failed to pip (PEIS) or complete hatch (PEPE) and a lower percentage of live fully hatched chicks (HI), when compared to those injected in the AC. Like HI, a lower percentage of female hatchlings was also observed at 22 DOI for the AM compared to the AC injection, except for the 6.5 x 102 CFU dosage. However, at all the dosages above the 6.5 x 101 CFU dosage, the AM injection resulted in a lower mean hatchling body weight at 22 DOI. In conclusion, E. coli populations were more prevalent in the AM than in the AC after the injection of the PECV in those sites. Furthermore, the injection of the PECV in the AM at all E. coli dosages generally increased late embryo mortality and decreased hatchability and hatchling body weight in comparison to an AC injection.