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

Abstract

The effects of injecting the Poulvac E. coli vaccine (PECV) into either the air cell (AC) or amnion (AM) at different dosages at 18 days of incubation (DOI) on Hy-Line W-36-layer embryo and hatchling development were investigated. Serial dilutions of the PECV in diluent provided either 6.5 × 104, 6.5 × 103, 6.5 × 102, or 6.5 × 101 CFU dosages of E. coli. A diluent only injection treatment was included as a control. A total of 19 live embryonated eggs in each of 10 treatment groups were represented on each of 16 replicate levels (3040 total) in the hatcher unit. At 19 DOI, swabs of the AM indicated that the 6.5 × 101 and 6.5 × 102 CFU dosages provided a 50% level of PECV presence, whereas the 6.5 × 103 and 6.5 × 104 CFU dosages provided a 100% level of PECV presence. Conversely, only the 6.5 × 103 and 6.5 × 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) (p = 0.001) or complete hatch (PEPE) (p ≤ 0.001) and a lower percentage of live fully hatched chicks (HI) (p ≤ 0.001), when compared to those injected in the AC. Like HI, significantly lower percentages of female hatchlings were also observed at 22 DOI for the AM compared to the AC injection, for all dosages except for the 6.5 × 102 CFU dosage. However, at all the dosages above the 6.5 × 101 CFU dosage, the AM injection resulted in a lower mean hatchling body weight (p = 0.010) 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. It is concluded that the negative impact of the in ovo administration of the PECV in the AM at 18 DOI on the hatch process is dose dependent. However, effects of an increase in AC dosages and a decrease in AM dosages should be further investigated.

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

“…All serial dilutions were performed in sterile Marek's disease commercial diluent (Merial, Inc., Athens, GA), and all titer determinations were determined from duplicate plates and were performed as described by Lindsey et al (2022) . Upon plating the full dose of the PECV, pre- and postinjection titers (CFU/mL) were observed to be 8.8 × 10 9 and 3.4 × 10 9 , respectively.…”

“…The injection process took a total of 1.5 h to complete. Cross-contamination prevention between treatments was as described by Lindsey et al (2022) . One egg from each tray (6 per treatment) was randomly selected to determine the accuracy of site of injection ( Elliott et al, 2018 ) and embryonic developmental stage ( Avakian, 2006 ).…”

“…In a previous study conducted by Lindsey et al (2022) , it was shown that although the in ovo vaccination of 6.5 × 10 3 and 6.5 × 10 4 CFU of PECV provided a 100% level of E. coli presence in the AM, those levels led to significantly higher embryonic mortalities and a subsequently lower percentage hatchability of eggs that contained live embryos at the time of injection when it was administrated in the AM rather than air cell. For a better understanding of the effects of the in ovo administration of the PECV in commercial layers, in addition to a comprehensive determination of the effects of different doses of the PECV on the hatching process, a more extensive subsequent evaluation of the various quality characteristics of hatchlings is necessary.…”

Advances in Poultry Vaccines: Leveraging Biotechnology for Improving Vaccine Development, Stability, and Delivery

“…A novel approach in biotechnology is the use of in ovo vaccination, which involves making a small hole in the blunt end of a chicken egg using an obliquely pointed needle and then delivering a small amount of vaccine into the amniotic cavity using a smaller needle [ 174 ]. In ovo administration is a way of delivering the vaccine into the egg to benefit the developing late-stage embryos before the completion of the incubation period [ 175 ]. It is usually performed at a limited time frame of the incubation when the eggs are being transferred from the setter to the hatcher units, giving advantages such as the capability to vaccinate a larger number of eggs, cost-effective, low human errors, and faster and better immune responses [ 176 ].…”

“…The efficacy of the vaccine and safety of the embryo depends on the sites of the vaccine administration, including the air cell (AC), allantoic sac (AL), amnion/amniotic fluid (AM), embryonic body (EM), and yolk sac [ 178 ] ( Figure 8 ). For example, vaccines administered into the AC and AL generally show low efficacy as compared to those injected into the AM [ 175 ]. Experiments conducted by Alqhtani and colleagues have suggested that the embryonic mortality in the case of vaccine delivered into the AC and AL is lower; however, the development of humoral immunity is not sufficient and is significantly lower as compared to those injected into the AM [ 179 ].…”