Effects of the in ovo injection of an Escherichia coli vaccine on the hatchability and quality characteristics of commercial layer hatchlings

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

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2023
Publication Date: 9/9/2023
Citation: Fatemi, S.A., Lindsey, L.L., Evans, J.D., Collins Elliott, K.E., Leigh, S.A., Robinson, K., Mousstaaid, A., Gerard, P.D., Peebles, E.D. 2023. Effects of the in ovo injection of an Escherichia coli vaccine on the hatchability and quality characteristics of commercial layer hatchlings. Poultry Science. 102(11):103057. https://doi.org/10.1016/j.psj.2023.103057.
DOI: https://doi.org/10.1016/j.psj.2023.103057

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. This research examined the impact of in ovo delivery of a live Avian Pathogenic Escherichia coli vaccine on the hatchability and quality of in ovo-vaccinated chicks. Hatchability and chick quality were both negatively impacted by the in ovo delivery of the live Avian Pathogenic Escherichia coli vaccine, but results were dependent on the dose provided to the embryonic chick. Likewise, chick quality was also negatively impacted in a dose dependent manner. In summation, the increase in the vaccine concentration administered in the embryonated hatching eggs at 18 days of incubation decreased both hatch success and chick quality.

Technical Abstract: In the commercial egg industry, avian pathogenic Escherichia coli (APEC) can lead to significant economic loss. The Poulvac E. coli vaccine (PECV) is a commercially available attenuated live vaccine commonly applied via spray or drinking water to protect against losses associated with colibacillosis. The PECV has not been tested in layer hatching eggs using in ovo injection. Therefore, the purpose of this experiment was to determine the effects of injecting 50 µL of different doses of the PECV into Hy-Line W-36-layer hatching eggs on the hatchability and quality characteristics of hatchlings. At 18 d of incubation (DOI), treatments included one non-injected and one diluent-injected control. Furthermore, PECV treatments included a full dose (4.4'×'108 E. coli CFU) or serial dilutions of the full dose to produce 4.4'×'106, 4.4'×'104, or 4.4'×'102 CFU doses of E. coli. In ovo injections targeted the amnion. Percent hatchability of live embryonated eggs (HI), percent residue eggs, hatchling mortality, and female chick whole and yolk-free BW, relative yolk sac weight, and body length were among the variables examined. Treatment significantly (P < 0.0001) affected HI, with HI being highest in the control groups (97.3% in the non-injected and 94.2 % in the diluent-injected), and with HI values being 89.0, 88.9, 84.4, and 71.2 % in the 4.4'×'102, 4.4'×'104, 4.4'×'106, and 4.4'×'108 CFU E. coli dose treatments, respectively. The percentage of live embryos that did not complete hatch but that pipped internally (P'='0.024) or externally (P < 0.0001) were significantly affected by treatment, with percentages being highest in the 4.4'×'108 CFU treatment. Female chick body length was significantly (P < 0.0001) affected by treatment and was longer in both control groups and in the 1'×'102 CFU E. coli treatment in comparison to all other treatments. Yolk-free female chick BW was significantly (P'='0.034) affected by treatment and was lower in the 4.4'×'106 CFU and 4.4'×'108 CFU treatments when compared to the diluent-injected control group. An increase in the E. coli concentration administered in the amnion of embryonated layer hatching eggs at 18 DOI decreased hatch success and female chick yolk-free BW and body length.