In ovo administration of the Marek's disease vaccine in conjunction with 25-hydroxyvitamin D3 and its subsequent effects on the performance and immunity-related characteristics of Ross 708 broiler hatchlings1,2,3

The combined effects of the in ovo injection of commercial Marek's disease vaccine (MDV) and various levels of 25-hydroxyvitamin D3 (25OHD3) on the hatch variables, immunological measurements, and gene expression of Ross 708 hatchling broilers were investigated. A total of 5 in ovo injection treatments that were applied at 18 d of incubation (doi) included: 1) noninjected (control); or a 50 μL solution volume of 2) MDV alone; or MDV combined with 3) 0.6 μg of 25OHD3; 4) 1.2 μg of 25OHD3; or 5) 2.4 μg of 25OHD3. At hatch, hatchability of set and live embryonated eggs, hatchling body weight, hatch residue analysis, serum IgY and alpha-1 acid glycoprotein (AGP) concentrations, and the expression of genes related to immunity (INFα, INFβ, INFγ, TLR-3, and TLR-21) and vitamin D3 activity (1 α-hydroxylase, 24 hydroxylase, and vitamin D receptor) were determined. No significant treatment differences were observed for hatchability of set and live embryonated eggs, or for serum IgY and AGP concentrations. However, hatchling body weight was higher when MDV was combined with either 1.2 or 2.4 μg of 25OHD3 than when MDV was provided alone or in combination with 0.6 μg of 25OHD3. Also, in comparison to the noninjected treatment group, the expression of the genes for 1 α-hydroxylase and 24 hydroxylase was improved when MDV was combined with either 1.2 or 2.4 μg of 25OHD3. Lastly, expression of the genes linked to viral detection (TLR-3) and antibody production (INF-β) was increased in those treatments that contained any level of 25OHD3. These results indicate that in comparison to controls, the effects of MDV were observed to be greater on hatchling BW and splenic gene expression when it was administered in combination with the 1.2 or 2.4 μg doses of 25OHD3. Further research is needed to determine the posthatch effects of the administration of various levels of 25OHD3 in combination with MDV.

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

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 1 noninjected and 1 diluent-injected control. Furthermore, PECV treatments included a full dose (4.4 × 108E. 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 noninjected 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.